Home Article How to turn on heating in a buderus boiler

How to turn on heating in a buderus boiler

Questions to specialists of service centers on boilers Buderus

Boiler Buderus Logamax U004K-24. Now: In summer mode, the boiler spontaneously starts and runs for heating, as if it was in winter mode.

Turns on from 45 degrees, heats the coolant to 60 degrees (the device), turns off, the radiators are really hot.

Hot water is working, but when you open the tap of the hot water boiler began to turn on with a delay of 5 seconds, and when you close the tap, the boiler does not stop immediately, and slowly reducing the gas supply for about 5-10 seconds. What do you recommend??

It is necessary to check the sensor of the flow of hot water. it happens that the water leaks through the gland and does not turn off the chip in the flow sensor. The boiler thinks the hot water is on and heats it as hard as it can.

It turns out that the 3-way valve is in heating mode. That is why it heats the coolant in the radiators.

Also, the NTC sensor can go bad and tell the boiler is not the correct temperature. for example, that the coolant cooled down to 5 ° C and turn on the antifreeze mode.

Please help on the boiler Buderus Logamax U002-24K. When the heating is off. Water pressure in the system is below 1bar, when pumping water to 2bar, and when you start the boiler pressure rises sharply to 3 bar.

In a word, the pressure surges. Please tell me what this is and how to fix it?

If the pressure rises sharply when the pump is turned on. The pump builds up pressure and the manometer sees it. If the pressure rises sharply when the temperature of heating increases, it means that the expansion tank is not working.

I have a boiler Buderus Logomax U002-24K 7 years in service. A couple of weeks ago in the heating system as you move the radiators away from the boiler, the temperature on them less and less and the last 2 radiators are generally cold (no air in them). On the boiler, the temperature regulator on the heating is at 80 degrees.

Boiler turns on, runs for about 3 minutes, water gets to 70 and shuts off. Then in about 2 min. The boiler temperature drops to 40 degrees or even less and the boiler turns on again. It seems that the pump “under-pumps” the hot water.

At the same time the return flow to the boiler is barely warm. Question: Is it possible that the pump has stopped pumping pressure? So to say “triggered” or there may be some other reason? How to check the pump?

The condenser in the pump is usually triggered, the second reason. there is debris somewhere or if there is a filter (on the return). It or the heat exchanger or the supply pipe. Especially if the pipe is made of plastic.

Boiler Buderus Logamax U002-24 / 24K or U102-24 / 24K, I don’t know exactly. Help me figure out why the exhaust fan won’t start if its resistance is as specified in your manual?

If there is a request for heat. Blower (turbine) must turn on, if it does not turn on. Check the fan circuit. Relay on the board.

Boiler Buderus Logamax U002 24K. Never serviced. Started having problems with pressure in the heating system: within 12 hours it goes from 2 to 3 and starts to leak through the emergency valve.

After pressure correction the situation repeats. The pressure in the expander is normal, so is the make-up valve.

Sometimes when you turn on the hot water you hear a squeak from the boiler. Where to look and what to do? My suspicions about the heat exchanger, three-way valve, pump? How to determine for sure?

First check the make up valve, then the heat exchanger.

Boiler Buderus Logamax U104-24K works 9 years. In the “summer” mode the cold water does not turn on and does not heat. Turn on the “winter” all is normal.

I have a Buderus Logomax U002-24K boiler. A couple of weeks ago in the heating system as you move the radiators away from the boiler, the temperature on them less and less and the last 2 radiators are generally cold (no air in them). The boiler temperature regulator for heating is set to 70, heats from 40 to 60 and shuts off.

The heat exchanger was flushed six months ago. Your advice on what to check?

Your heating system is out of balance/adjusted. Tap the first radiator, then the second, then the third, etc.д.

We have two Buderus gas floor standing boilers in our country house. Do I have to do maintenance if I don’t have any problems with their operation?

Regular preventive maintenance is necessary for the gas heating equipment in any case. Service technician will clean the burner and combustion chamber, check the automation, check the functionality of the major components, clean or replace the filters. The more powerful the unit, the more often should it be serviced.

So, a boiler with a capacity of up to 70 kW can be serviced once a year, and over 70 kW. twice, plus the need for intermediate technical inspections. Boiler units with a blower burner require servicing more often than units with an atmospheric burner. All these measures make it possible to maximize the life of the battery without accidents.

Gas boiler Buderus when turning on has become very noisy, the pressure rises sharply, and drips from under the boiler, and on the display flashes error 6A. What does it all mean?

Error 6A means that there is no flame control. In conjunction with the phenomena described above, this can mean a pump air lock (air lock), failure of the supply line sensor or minimum coolant pressure sensor, there are still a number of reasons.

When turning on the wall hung gas boiler Buderus on the right from below begins to drip water from a valve. What does it mean??

There is a so-called pressure relief valve that is triggered in the event of an emergency. There are several reasons for this: not calculated pressure in the heating system, when the capacity of the expansion tank is not enough, the failure of the expansion tank and make-up faucet malfunction.

After installing a powerful boiler Buderus in a private home, the old chimney with a diameter of 150 mm, apparently will have to change to a diameter of 180 mm. What can you advise on this issue?

The atmospheric chimney with a diameter of 150 mm can, as an option, be left, but this will affect the efficiency of the boiler and the quality of gas combustion for the worse. Such a chimney will be strongly heated and transfer heat through the wall, which will lead to damage to the finish in this area of the house and the destruction of the brick outside. Buderus automatics allows you to work with a small chimney, but it is better to replace it with the diameter required by the boiler data sheet.

My 90 kW Buderus gas boiler is over 6 years old and the heat exchanger has never been cleaned. How often this procedure is necessary and at what time of the year? Can I clean the heat exchanger myself??

It is recommended that the heat exchanger be internally cleaned every 4 years. The time of year does not matter, the main thing is to observe the interval. Boiler is cleaned chemically using special reagents that dissolve scale and dirt inside the heat exchanger.

In our community is going to build a natural gas. Can I convert the diesel Buderus to gas, or will I have to buy a new machine?

To change the boiler to another type of fuel it is necessary to change the burner from liquid fuel to gas model. The cost of the burner is the main part of the cost of the unit, because it focuses all the automation and other expensive components on which the entire work of the device.

We have a gas boiler Buderus works in a country house, when you turn on the light does not light up, the burner and everything else does not work too. What do you recommend?? It is too far to go to the village, there is no way to call a master.

The boiler is likely to burn out the power supply. It is necessary to change the power supply module. If you decide to do your own repair of the gas boiler, the advice is this: the remote is attached to the module, and behind it there is a block with a transformer.

Remove the two connectors from it, and the mains unit is pulled out. There are 4 fuses on it that should be blown just in case. Thyristor on right side may be burnt out, need to replace it. For the future. UPS or AVR with short response time is needed.

During a heavy storm at night, the Logamatic 234 boiler shuts down and will not start again. No error message or response to anything. What should I do??

STB or draft reversal sensor seems to be out of order.

A diesel boiler with an Elco burner almost never shuts down. it heats up to 85 degrees, goes out, and the flare continues to burn on the display all the time. Soon the venting begins and the cycle repeats. What does it mean?

This operating mode means incorrect operation of the burner. Adjustment of oil burner by a device that analyzes temperature of flue gases and CO. This adjustment is required at least once a year and saves significant amounts of fuel.

I have a wall-mounted double boiler Buderus in my private home. The big jumps in pressure in the heating system. What’s the reason?

Good afternoon, we recommend to check pressure in an expansion tank of the boiler.

Is it necessary to have an uninterrupted power supply for a 73 kW BUDERUS gas boiler or is it enough to use a diesel generator??

Uninterruptible power supply provides an “instant” switching to an alternative power source in case of power outage, these sources can also be voltage stabilizers. Diesel generators have a substantially longer resource of time of power supply of their consumers.

I have this problem with the boiler Buderus Logomax 052U 28K. At switching on DHW pressure in the boiler falls to 0. Without DHW heating works fine. Advise what to do?

Check the expansion tank in the boiler. Possibly a punctured heat exchanger.

Removing the sensor

The water sensor is fixed by a small bracket, to remove it, you need to lift it up and remove the sensor itself from the hydraulic group. After replacing the sensor, the manipulation of its installation should be repeated in reverse order, not forgetting to fix it with a staple and connect the power connectors.

After replacing the sensor, check if the sensor is working properly and if error 2e will be displayed on the information panel again. To assemble the boiler it is necessary to install the front panel in the reverse order, fasten it with two self-tapping screws and install the information panel.

To turn on the boiler, you must open the water inlet tap on the heating system, then open the make-up valve and raise the water pressure in the boiler to 1.5 bar. Then you can connect the boiler to the power system and turn it on.

Logamax U044-24K. German quality at an affordable price is a simple and reliable wall mounted boiler for a private house or apartment up to 250 square meters. м. Boiler with an open combustion chamber, flue gas venting into the chimney and the intake of combustion air from the room. The boiler is designed for installation in closed heating systems.

Boiler output:

  • Boiler output control range for heating and domestic hot water preparation from 7.8 to 24 kW
  • Maximum gas flow rate 2,65 m³/h
  • Low noise level max 38 dB (like a refrigerator)
  • Efficiency up to 92 %
  • Maximum boiler water temperature (82°C max) and heating output can be limited.
  • Electrical power consumption 130 W (4.3 W in standby mode).
  • NOx emissions. class 2.

Hot water:

  • Hot water flow rate at 10.3 l/min at temperatures from 40 to 62⁰C Quick adjustment to the required amount of hot water with the integrated turbine. Comfortable simultaneous use of up to two extraction points.
  • Priority hot water operation.

Boiler design:

  • Control and safety equipment (expansion tank 8 liters, safety valve activated when the pressure exceeds 3 bar, water quantity control device, regulation and safety devices).
  • Electronic ignition, flame control with ionisation electrode.
  • Integrated frost protection system (for heating circuits) briefly switches on the burner and the heating pump if the room temperature in the installation room falls below approx. 9°C.
  • Anti-blocking pump system after every switching off the pump starts a countdown so that after 24 hours it can be switched on again briefly.
  • Open combustion chamber. Burner with premixing.
  • Boiler equipped with two draught dampers that shut down in the event of activation.
  • Burner operating on natural gas or LPG.
  • Control with switch and reset button.
  • Maximum boiler water temperature (max 82⁰С) and heating output can be limited.
  • Flue gas outlet connection 130 mm.
  • Boiler weight 33 kg, dimensions H740 x W400 x H360 mm.
  • Heating (¾”) and water (½”) pipes and gas (¾”) pipes are connected to the boiler at the bottom center at a distance of 158 mm from the wall.

Choice of mounting location for gas boiler Buderus Logamax U044-24K

Fig. Overall and mounting dimensions and connections of gas boilers Logamax U044-24K (dimensions in mm).

The atmospheric boiler U044-24K can be placed in a dry, non-residential room of at least 2,5 m height and volume of at least 7,5 cubic. m (e.g. kitchen or boiler room) with natural light (window area not less than 3% of the room volume) and a permanent supply of outside air through a wall, window or door (opening min 0,025 m2 ). м). When installing the boiler, it is necessary to follow the minimum installation dimensions given in the picture below.

Installation in the bathroom: not allowed.

Basement installation: permissible if all the space requirements are fulfilled (see “Installation in basement”). above).

Installation in closet: ventilation openings and minimum distances as shown in the figure are necessary. The maximum surface temperature of the boiler does not exceed 85 °C. Therefore, special protection measures for combustible building materials and built-in furniture are not required in this case.

Combustion air: In order to prevent corrosion of boiler parts, the combustion air must not contain any aggressive substances (halogen hydrocarbons, containing chlorine or fluorine compounds). They may be contained in e.g. solvents, dyes, adhesives, aerosol sprays and household detergents.

Mowing line supply temperature

In the boiler Logamax U044-24K the following parameters can be set with the supply temperature regulator in the heating system:

  • For underfloor heating: e.g. 50 °C or less (for underfloor heating systems the maximum permissible supply line temperature is 50 °C)
  • For low temperature heating: e.g. 70
  • For heating with a supply line temperature of up to 82 °C (maximum permissible value): 80

The temperature indicator will show the actual temperature in the supply line of the heating system.

Hot water temperature

The hot water temperature regulator allows to set the temperature between 40 and 60°C. The hot water temperature is not shown on the display. The higher the set value, the lower the hot water flow. For example, when set at 40-50°C, the flow rate is max 10 l/min, at 55°C max 9 l/min, and at 60°C max 7.5 l/min.

Economical heating through continuous regulation

Boiler design ensures the lowest possible gas consumption and environmental pollution with a high level of comfort. The gas supply to the burner is regulated according to the heat demand for domestic heating. When reducing the heat demand, the U044-24K boiler continues to operate with reduced flame constant regulation mode.

Due to the constant regulation the minimum temperature fluctuations and uniform distribution of heat in the rooms are ensured. As a result, it is possible that the boiler is in continuous operation and yet consumes less gas than an appliance that switches on and off intermittently.

Inspection / maintenance

In order to minimize the consumption of gas and environmental pollution during the long term operation of the boiler, the boiler manufacturer recommends to conclude a contract with a specialized company for the annual inspection and maintenance of the boiler.

Heating regulation system

For additional savings, you should install a room temperature regulator and thermostatic valves on the radiators.Then the boiler will independently regulate its output to maintain a constant desired temperature in the room where the room regulator is installed. The thermostatic valve on the radiator in the control room (where the regulator is installed) must be fully open.

In this case, the boiler will not waste energy to overheat the water in the heating system and gas consumption will be reduced.

Floor heating

Do not set the temperature of the supply line to the floor heating system above a maximum of 50 °C.


To ventilate, do not leave windows open in a tilted position. Otherwise heat continuously escapes from the room without a noticeable improvement in indoor air quality. It is better to open the windows fully for a short period of time. Close the thermostatic valves in the room when ventilating.

Hot water

Always select the lowest possible hot water temperature. A lower thermostat setting results in greater energy savings. In addition, at high hot water temperatures there is increased scaling which impairs the function of the appliance (e.g. longer heating up time or less water).

Chemical additives in the heating system water approved by the manufacturer of boiler Buderus Logamax U044-24K

To ensure that the boiler operates as long as possible, it is best to fill the heating system with water free of impurities. But sometimes, for example due to frequent power outages, it is necessary to add chemicals to the heating system water. Only add products recommended by the manufacturer in order to maintain the warranty.

Name Concentration Type Purpose
Tyfocor L 25 80 % Antifreeze Anti-freeze
Antifrogen N 20 40 % Antifreeze Antifreeze
Cillit HS Combi 2 0,5 % Anticorrosive Against Corrosion
Copal 1 % Anticorrosive Against corrosion
Nalco 77 381 1 2 % Anticorrosive Anticorrosion

Sealant is not recommended, as its addition to the heating system water can lead to deposits in the heating unit.

Putting into operation and maintenance of the boiler Buderus Logamax U044-24K

Installation, gas and chimney connection, initial commissioning, power supply connection, as well as maintenance and routine maintenance works may only be carried out by specialists of authorized firms.

To reduce to a minimum the gas consumption and pollution over a long period of operation of the boiler, the manufacturer recommends you to conclude a contract with a specialized company for the annual inspection and maintenance of the boiler. Our service department works in Kiev and region without days off. The list of service centers in other regions of Ukraine you can find on a site of boiler manufacturer Buderus Logamax U044-24K.

If you need advice on this boiler, a complete set of boilers and / or installation of the boiler (in Kiev and region) call (050) 380-49-62 Igor Potupchik our engineer will answer your questions any day from 9 to 20. Or leave your phone number in the form below and we will call you back.

Malfunctions and breakdowns in the boiler Buderus Logamax

Wall-mounted single-circuit boiler Buderus Logomax U072-35 doesn’t start. When you hold the button on, the burner works fine. As soon as the button is released, the unit immediately goes out. What’s the cause of the malfunction?

Thermostat or gas valve seems to be defective. There’s also a drop in gas pressure on the supply line. Sometimes the voltage of the electronic board is too low.

Malfunction has occurred. It is difficult to start. Ignition burner ignites, but there is no flame on the main burner. Help me find out what’s wrong?

Possibly a malfunction in the ignition mechanism. You will need to service the boiler and clean the ignition mechanism.

For what reasons the gas boiler Buderus Logamax U052 does not turn off when the heating reaches the desired temperature? It heats up to 90C, then goes into a crash. The situation starts up again after restarting.

Apparently, the control board fails, the temperature sensor is damaged, the protection sensor button is broken. It cannot be ruled out that a malfunction of the automatics has occurred.

Could you please tell me why it is not possible to raise the temperature of the heating medium above 70 C?? We need to increase the temperature, but the display shows that this is the highest value. How to increase the heating?

In the case that the device can not increase the temperature in the heating system, you can assume the following factors. In the settings set the limit on the highest temperature of heating no more than 70 degrees. The chimney draft has dropped.

Wall hung gas boiler Buderus Logomax 24 unstably began to work in the cycle of DHW heating. From the faucet in the kitchen can flow alternately hot and cold water. Tell me why this happens?

Water often leaks from the tap at the bottom of the boiler. The appliance itself can’t start. What to do?

Most likely the coolant is leaking from the safety valve. This situation means that the pressure in the system is high. Also the system make-up valve may not be closed or the expansion tank must be inflated.

Could you please tell me the reason why the pressure increases regularly and why the reset valve starts operating?? On the display always flashes the heating symbol in the heating cycle of the appliance. What happened?

There is a failure of the temperature sensor of the heating circuit. There is no normal circulation in the heating system.

What is the problem, if your Buderus Logamax U072-24K double boiler regularly shuts down?? For example, recently the piezo ignition did not work at all. Has the appliance been serviced this week? What kind of malfunction?

There seems to be a problem with the smoke evacuator. You need to check the chimney. Failure of the piezo-ignition function means that one of the components is worn after a power surge or that water has entered.

Please help troubleshoot the chimney problem? Soon it is three days since the return draught appeared, when the smoke began to fly immediately into the room. I made the chimney myself. It consists of a metal pipe. It seems that there was a mistake in the calculations.

Unit operates normally in domestic hot water cycle, but if you start heating, water boils and the unit stops. What can be wrong and how to fix it?

Probably the circulation pump is out of order, the electronic board is out of order, or the temperature sensor is broken. At the same time the filter screen could be clogged.

While supplying hot water, the boiler alternately supplies hot and cold water. It is unclear what it depends on. How to correct the heating of the water?

Possibly the heating system is clogged or the heat exchanger needs cleaning. Also the pressure control sensor may be defective or the circulation pump may be faulty.

The main reason can be wrong chimney configuration. It is possible soot deposit on the walls of the chimney, which sufficiently reduces its effectiveness. It is also recommended to check the ventilation holes in the house.

Operating a single-circuit boiler Buderus Logomax U072-18. It instantly sets the temperature over 96C, but then crashes with overheating. Later, when it cools down, it goes to reset. How to fix the breakdown?

Failure of the overheating function indicates a malfunction in the circulation process. Initially, radiator taps must be monitored. They must be left open. After the filter element is checked for cleanliness, and you must also make sure that the heat exchanger is not dirty.

Started this boiler in the fall of this year. Sometime after a few weeks the device began to make a lot of noise. Explain the reason for the noise?

Presumably, the presence of scale in the heat exchanger. When the water is hard, over time in the radiator lime is deposited on the wall of the pipes.

We are thinking of connecting a wall mounted boiler Logamax Plus GB172 in a private house. Please tell me how to put this unit into operation correctly yourself?

For the correct start-up of this equipment it is necessary to perform the following actions. Connect the electrical power supply to the appliance. Turn on the gas tap. Then start the burner device. Finally adjust the desired temperature.

We need to do maintenance. Can you advise how to drain the water from the unit yourself??

According to the manual, this operation is done as follows. Disconnect the appliance from the power supply. Close the gas valve. Open the automatic air vent. Turn the drain cock. After that, remove the leaking water. If necessary, allowed to drain the liquid through the drain valve. This valve is located on the bottom of the unit.

Can you tell me how to diagnose the operation of the three-way valve? There is a suspicion that this component does not perform well in opening. On the heating system can not pump the outermost radiators, but on the hot water supply pipe under the boiler is warm.

You are correct, we recommend that you look at the 3-way valve for an oxidation of the stem in the intermediate state. It is also advisable to make an inspection of the heating system itself.

I use a Buderus U072-18K gas boiler in my country. It was working fine until last night. But now 5 seconds after turning on the unit goes out.

turn, heating, buderus, boiler

Can’t seem to get any coolant into the system. Please help me, what is the source of the problem? A possible factor of this malfunction could be the ignition electrode, which does not register the flame, or a decrease in the circulation process.

A few days ago there was a problem with the heater. It started whistling when it worked. I decided to do a restart. succeeded, but there was no change. Tell me why the machine whistles?

Very often a strong whistling occurs when the pressure on the gas burner nozzles is not made according to the instructions. It is necessary to check the set value and correct it, if it is advisable.

Water got into the boiler yesterday and the unit started working with delays. For example, set any temperature and it only reaches 24 degrees and then the unit crashes. Please tell me what happened?

If water gets on the electronic board unit, most likely it has deteriorated. Advise you to reset it using the linear shutdown of the unit from the power supply. Then turn it on again and see if it works.

A year ago we connected the U042-24K model to the system. Now at the moment of start the wick lights up for 10 seconds, the main burner does not catch fire, and because of this the machine goes out. How to remedy the malfunction?

It seems that the automatic ignition is damaged or there is a problem with the burner. In any case it is necessary to check whether the phasing has not been disturbed when connecting to the mains.

We put the same appliance into service in October of the same year. Presumably after five months there is a problem with the hot water supply, although the heating works fine. I tried to open the hot water tap, but it only indicates the temperature and does not heat. Can you tell me what the reason is??

Most likely there is a breakage of the three-way valve. It needs to be replaced.

I would like to know for what purpose a safety temperature sensor is installed in the boiler?

This component stops the gas supply to the burner if the water in the primary system overheats.

I need to flush and clean the primary water heat exchanger. Please help me what to do to remove it correctly?

The primary heat exchanger can easily be removed from the boiler unit with a normal screwdriver. Below is a description of the removal procedure. Drain the water from the unit using the outlet valve. Next emptying the hot water system. Unscrew the screws fixing the heat exchanger and remove it from the frame.

Carried out the start-up with this model. Presumably after six months the water pressure in the unit began to decrease. Often, it’ll go down and it won’t work. Or, more accurately, it can’t hold pressure at all. What’s the problem?

When the unit does not raise water pressure, the make-up valve is most likely leaking. If a shutdown occurs and water pressure drops to 0, the three-way valve is defective.

Explain how to clean the cold water filter on the U072-12K?

Initial step. Drain the hot water system. Second, unscrew the nut of the flow sensor. Next, remove the sensor and filter from the socket. After that remove accumulated debris and dirt.

The appliance was humming during start-up before, but now the noise has increased. At first the sound disappeared quickly, but now it lasts longer. Has anyone seen this problem?

The noise can be explained by the lime scale inside the heat exchanger, which does not heat up evenly due to the uneven wall thickness. The more the heat exchanger is clogged, the noisier the unit and the reduced heat output.

The unit is functioning, although the system clearly does not circulate water. Return pump is very hot. Why heat up?

Most likely the filter is clogged or at some point there are closed taps and this is slowing down the flow of coolant. The circulation pump could also be defective.

Why can not get hot water? The water flows from the tap almost cold. Please help me to understand the reason?

Finding out the problems are. For example, the temperature sensor for DHW is defective, it must be replaced. Possibly the water heating capacity of the appliance has malfunctioned.

Occasionally there is a spark disruption at the moment of ignition. The burner is clean, the chimney is fine, the draught is good. Where to look for?

The device does not register the spark due to an insufficient signal from the combustion mechanism. Need to diagnose the wiring between the ionization sensor and the electrode. Apparently it needs to be tightened. There may also be damage in the sensor insulation, which must be replaced.

Problems of Buderus Logamax boilers

Tell me what the breakdown is when the Buderus Logamax U072-24K gas boiler goes out?

Flame detection malfunction. Bad gas pressure. Lack of gas supply. Faulty gas valve. Defects in the ignition mechanism parts or broken connections. The electronic board can also be defective.

It is not possible to find the cause of damage if the boiler shuts down? Has anyone experienced this problem? We have been using the boiler for a total of six months.

Causes of shutdown may be incorrect capacity of appliance, low gas pressure, problems with flue gas venting, power surges, automation damage.

Can anyone explain why the pressure in the heating boiler is dropping? The unit was connected last year. How you can fix it?

Large amount of air in the heating circuit. The air bleed valve is defective. It must be replaced. The filter of the heating system is clogged with dirt. Clean the filter. There is a leak in the boiler itself or in the heating pipe. Failure of the make-up valve. Malfunction with the flow switch. Test and replace if necessary. The circulation pump is damaged. Low rpm due to damaged blades.

Can you explain what is the cause of malfunction if the wall hung gas boiler Buderus Logomax doesn’t switch on?? How to remedy?

Long ignition duration of the gas burner indicates that the flame sensor is blocked. To remove the problem it is required to clean the sensor and re-start the unit. Damaged draft sensor. Gas supply to the burner is blocked. We recommend to clean the sensor or install a new one.

Can someone explain what is the cause of damage if the gas boiler does not heat water? How you can eliminate? We are using the machine for exactly six months.

Check the filter of the main circuit. If the filter is clogged, disassemble and clean the filter element. Hydraulic circulation pump blades are defective. Inspect the hydraulic pump and replace if necessary. Also check the liquid circulation in the heating pipe. Wear or contamination of heating pipes reduces the amount of circulating water, as a result of which the device will not work properly for heating.

Explain to me how to fill the boiler with water?

This procedure should be performed according to the following scheme. Open vent valves installed in radiators, and monitor the operation of the air vent in the boiler. Slowly open the make-up tap, monitoring the reliability in the operation of each of the air vent mechanisms of the heating system. Close the air vents on the radiators if you notice any water. Then close the make-up valve and bleed the air again using the valves on the radiators. Start the unit and bring the heating to the desired temperature in the heating circuit, then turn off the hydraulic pump and perform secondary venting.

Can you tell me what the problem is if the single-circuit boiler Buderus Logomax lights up and goes out? How to fix the problem? We have been using the boiler for only six months.

No flame registered by control board: wrong neutral and phase connection. Connect the phase and zero correctly. If there is no improvement, the board must be replaced. The ignition electrode wire is damaged or disconnected. Connect or change the wiring. The gas pressure is extremely low. Increase it.

Can you please tell me what the problem is if the boiler stops starting?? The unit was connected the year before last. What I have to do?

No ignition. The gas mixture is not being fed. Open the gas valve and check the pressure. Inadequate electrode spacing or bending. Lack of electrode arcing. It appears that there is an interruption in the input supply.

Why during the start of the gas boiler you hear a strange knocking, and then the gas burner starts to go out. Error appears on the display indicating overheating. We are advised to change the heat exchanger. How to fix the problem?

Unit shutdown due to fluid overheating does not always depend on clogged heat exchanger. Strange noises can also be heard if there is a large amount of lime deposits on the heat exchanger ribs and if there is air in the heating circuit. Check first of all that the temperature sensor, 3-way valve and built-in circulation pump are functioning correctly.

Why wall mounted gas boiler Buderus Logamax U072 clicks during set temperature? For example, the burner unit ignites, the temperature rises, then there is an unusual metallic clatter. But if you remove the screws fixing the front trim, then no humming sounds. What’s the reason?

In some cases, the appliance emits a crackling and humming noise mainly when the main gas burner is switched off. The main reason for this problem is the disproportionate heating of the heat exchanger fins, due to clogging or lime scale. We advise you to remove the scale and dirt from the heat exchanger immediately.

What are the reasons why the gas boiler does not turn off when heated to the set temperature? It heats up to 85C, then it crashes. If you carry out the resetting, the cycle starts again.

Perhaps the electronic board is damaged, the boiler water temperature sensor is broken, the safety sensor button is broken. It is possible that an error has occurred in the automation.

Advise me how I can reduce the pressure on the boiler Buderus Logamax U052? And whether it is possible to reduce the gas pressure? There is a regulator in the unit, which corrects the gas pressure or it is not desirable to make such adjustments?

The regulator allows you to adjust the gas pressure going into the appliance. If it is very small, the gas burner does not ignite, when it is increased, the flame pulls away from the wick, and the burner extinguishes immediately after ignition. Further steps in the correction. Warm up the appliance intensively. Open the whole flue. Set the main burner to the maximum level, the flame will be yellow-blue. Close the gas valve and turn off the yellow flame. Then test the operation of the appliance in several modes.

From the tap under the boiler is often dripping. The device itself does not start. What to do?

Apparently, the coolant is discharged from the valve. This factor indicates a high pressure in the system. In addition to this may be an open makeup valve system or should pump the expansion tank.

Tell me why the pressure jumps upwards and at the same time the bleed valve is open? The screen gives endless heating icon when the boiler is heating. What can be done?

There is a failure of the temperature sensor of the heating circuit. Stopped the proper circulation process in the heating scythe.

Bosch Buderus Boilers Overview

Recently there is a problem with the boiler Buderus Logamax Plus. In heating mode, it whistles. Decided to reset it. It worked, but the whistling does not go away. Tell me why this is happening?

Often a sharp whistle occurs if the pressure at the nozzles of the gas burner is not carried out according to instructions. It is required to check the set value and correct if appropriate.

After 5 years of faultless work the following problem occurred. When we turn on the heating mode, the pressure rises sharply at the moment of heating, and the water starts to dump out accidentally. Why it happened?

Maybe the diaphragm of the expansion tank is worn or the air chamber has no air. Also possible defect in the 3-way valve.

The machine could rattle when turned on, but now it rumbles even more. Initially the sound was heard briefly, but now it lasts much longer. Has anyone seen this problem?

The appearance of unnecessary unpleasant sound shows the presence of mineral deposits inside the heat exchanger, which heats differently due to the different thickness of the walls. The more dirty the heat exchanger, the louder the noise is, due to which the heat output is reduced.

We calculate in a country house to install a gas boiler Buderus Logamax 24 kW. Interested in how to properly start such a unit in operation?

To put this appliance to work correctly, you need to do the following operations. Switch on the electrical supply to the appliance. Open the gas valve. Then turn on the main burner. To finish we adjust the desired temperature.

Explain how to clean the cold water filter?

First we have to drain the hot water system. Next step. Unscrew the nut from the flow switch. Then remove the sensor together with the filter from the recess. After removing the impurities and dirt.

Why can’t the hot water be heated?? The water is very warm. Can you explain what happened?

You can conduct troubleshooting in the following directions. If the DHW temperature sensor is damaged, it must be replaced. It is also possible that the appliance power setting for water heating is off.

Can someone please help solve the chimney problem? Already two days there was a reverse draught, because of which the smoke began to fly immediately into the kitchen. The chimney was made by me. It represents a pipe made of steel. There may be some omissions somewhere.

The main factor can be wrongly executed chimney structure. There can be contamination of the chimney by combustion products, which significantly reduces its efficiency. In addition, it is necessary to control the exhaust ducts in the room.

All main error codes and decoding

Let’s consider the main error codes of Buderus boilers:

Code Deciphering of Ways to eliminate the problem
H11 Malfunctioning of the D.H.W. temperature sensor Check the contact group, determine the sensor efficiency, replace it if necessary
2P Overheating of the heat transfer medium Check contacts, determine condition of circulation pump
Stopping the fan Check the contacts, replace the fan with a new one
4C Heat exchanger overheating Stop the boiler, check the efficiency of the circulating pump and the temperature sensor of the hot water, call a master
4U, 4Y Short circuit or breakage of temperature sensor of direct mowing line (supply) Check condition of sensor and contacts, clean and reconnect, if necessary replace sensor
No flame Check the presence of gas in the system and in the boiler equipment, call specialists
3C, 3L, 3P, 3Y Fan failure Check connection and serviceability, replace
System sees flame on non working burner Moisture on the contacts or control board, bad earth contact

Connection of the boiler Buderus Logamax U072

Connection of on/off regulator or Open-Therm regulator

Open control box to connect power supply line.

Putting the boiler Buderus Logamax U072 into operation

1-Drainage hose, 2-Return heating line tap (optional), 3-Cold water tap (optional), 4-Gas tap (closed) (optional), 5-Hot water, 6-Feeding heating line tap (optional) 7-Return button (exit service function/submenu without saving), 8-Ak button (confirm selection, save value), 9-Display, 10-Automatic air vent, 11-Button “”, 12-Button “. ” (mode), 13-Button “Stand-by”, 14-Gauge, 15-Filling device

Before starting the boiler Buderus Logomax U072:

1-Burner operation, 2-Fault indication/stand-by mode indication, 3-Hot water mode active, 4-Hot water preparation active, 5-Summer mode active, 6-Service mode, 7-Temperature indication (in °C)

Setting the gas supply (natural and liquefied gas)

1-Measuring connection (nozzle pressure), 2-Maximum flow regulation screw, 3-Cover, 4-Maximum flow regulation screw, 5-Pipe for measuring gas pressure

Gas pressure at nozzles at maximum heat output

Checking and maintenance of the boiler Buderus Logamax U072

Cleaning the burner pan, nozzles and burner sit

Checking the expansion tank

During the annual inspection of the expansion tank it is necessary to:

Control and settings of boiler Buderus

In operation recently installed gas wall mounted boiler Buderus logamax U072-24k two-circuit. The house is 80 square meters. м., 2 floors, non-permanent residence, Leningradka heating system, additional pump in the return flow. At first start constantly turned on and off, the house is heated to 24 degrees. After the ZONT control was installed with supply and air temperature sensors. The comfort temperature is set to 26. The boiler turns on once every 3-4 minutes, heats the coolant to 80 and then drops to 26. The temperature in the house does not rise above 20. The radiators are not all heated up. Pump speed 2. The boiler power is reduced by 50%. Installed the type of professionals. Where to get the normal ones, I do not know. What can be the reason, the settings of the unit or ZONT? Should the boiler start so often?? Why can it be, such a big difference between the temperatures in the flow and return?

Clean the sludge trap, reduce power to 30-35% (for now). With your area a second pump is not necessary. Unless something is wrong with the heating. And so the built-in with a 2-3 reserve is enough. Turn off the 2nd pump for now.

Made installation and connection of a gas boiler Buderus Logamax U072-24K (single-circuit with an opportunity to connect the boiler). I plan to install a boiler indirect heating. 1. I don’t have a boiler mode active right now. It will have to be programmed later or as soon as I connect the sensor to the boiler, it will become active? 2. What sensor should be used in the boiler for this unit (ideally with a code, may be analogues or sensor parameters)?

The sensor is better to get a Buderus, when you connect the sensor the boiler itself will detect it, you may need to turn off / on. make.

If we turn off the pump, it has no bypass, it will slow down the circulation? Power decrease. The ZONT control can be turned off altogether? And what to do with circulation? The first time we started it without Zont, it heated all the batteries, but it was so strong.

The umbrella has nothing to do. It only commands the boiler to heat until the set temperature is reached. Remove it, put a jumper. Will be the same and then worse. The fact that the boiler heated up to 24 in the first start-up confirms the theory with the fan. Clean! And when everything is normal, still consider the purchase of Open-therm to control the Zont.

Please tell me, the washer under the coaxial chimney is not installed at Logomax U072-18K? Looked at the manual for it, not a word about the washers. And there are no washers in the kit.

It doesn’t. Adjustable fan speed.

Serviced a wall mounted boiler logamax U072-24k. Dirt trap cleaned. Was almost clean. For a week, the boiler was working in non-freezing mode, periodically zont sent the message “temperature is below the threshold”. Yesterday, added to the temperature, the room is heated to only 12 degrees (last time 20). On arrival, the monitor showed an error CP, however, the boiler switches on and off. There is no boiler, why this error is unclear. Resetting it is unsuccessful. Cleaned the strainer and disconnected zont to make sure it is not the problem. The boiler does not turn on at all, the SR is still on. What to do?

Check and set the parameters in 3.1A or do a factory reset in 2.8E. If, having switched off the umbrella, you have not put a jumper. Boiler will not start. In the relay mode (your current) umbrella is only a remote jumper switch for the boiler. You can work, forbid to work. And how to work, at what temperature of the coolant. All in the boiler settings. So your problem is not the umbrella! Boiler settings, hydraulics, heat output of radiators. That’s where you need to look. Anti-freeze mode is set to 6 degrees, and the boundary of the air temperature sensor is 5, operating mode. Relay on/off, the temperature of the coolant is limited on the boiler itself.

Yesterday I connected the thermostat CR12004 with opentherm to the boiler Buderus 072. Specialists in this forum write that the thermostat is not just a programmer on/off the boiler, but also a smart device that sets the temperature of the coolant based on its own calculations and algorithms. Is it true? And how it all works? Is it necessary for the completeness of the settings to have an outdoor temperature sensor, which I do not? From the device is fed by the branch to heat water and caisson for the well pump. This branch is insulated and buried half a meter. Runs 20 meters underground from the house to the caisson. The boiler turns off when the room temperature is reached, and after a short time the pump is turned off. which for me is a danger of freezing the water for the caisson. I can increase the shutdown delay to 10 min, but I’m afraid that won’t fix the problem. Is there any way to leave the pump always on?

Can you advise which unit to choose to control the boiler by room temperature?? I have a wall mounted boiler Logomax U052-24K. At a minimum, I need a temperature control, the weekly programmer is secondary, only if the minor cost between the two.

RC10, RC25, RC35, RC100, RC200, RC300 control units

If the DHS heat exchanger is clogged, can I shut off this circuit and install an indirect water heater on the heating circuit? I have a 24 kW boiler is now set to 10 kW, more than 60 degrees I do not heat the coolant. In a house of 140 meters the first floor is heated from the warm floor through the mixing unit, the second floor of 5 radiators Kermi with thermal heads and towel dryer. In summer, the boiler only heats the towel, and so would heat water in the boiler. Boiler can be connected through a three-way valve. A large boiler, we do not need, we do not have a bathtub. Liter 100-120 will be enough. Working scheme?

Yes, working. To the boiler pump and emulate the flow sensor. Pump to heat. Bithermics boiler pump in DHW mode is disabled. The flow sensor is the one that tells the boiler to heat the heating or hot water. If DHW 30-40 max will do, then instead of a 3-way pump.

Who can competently describe the algorithm of single wall mounted boiler Buderus logamax u072-24k with BKN? I did not find a manual specifically on single-circuit boiler instructions are common and there is no schematic diagram. Do I understand correctly, the unit has two pipes to connect the heating system (supply and return) and two pipes to connect the BKN coil (also supply and return). A thermocouple from the boiler is connected to the boiler. The boiler is operating in heating mode, let’s say at a set temperature of 60 degrees Celsius. A pump is pumping coolant through the heating system. Water temperature in the boiler is set separately. Let’s say 65 degrees Celsius. Then we open the hot water tap, the temperature drops in the boiler, the thermocouple sends a signal to the boiler and the three-way valve switches to the boiler coil circuit, the boiler goes to maximum power (?) And the same pump now runs coolant through the coil. Is everything correct in my understanding? What thermocouple can be connected to the boiler? Anything special or from any BKN? Or they don’t come with the boiler. Perhaps you can advise BKN liter 100-120 with the possibility of wall mounting and thermocouple?

The thermocouple is a slightly different device. This uses an NTC temperature sensor, as1 or as1.6. Only floor standing boilers, e.g. Logalux S120.

In single-circuit Buderus 072, the loop coil BCH heats the same heat exchanger that is on the heating or the same as the 2 circuit that is on the DHW?

Buderus Logamax Plus GB142 Gas Wall Hung Boiler Not Working

Can you tell from experience how the secondary heat exchanger Buderus logamax u042 scale is formed? Is it only in the area of the heat exchanger or is there a deposit on the pipe?? The condition of the tube in the area of the flow sensor can understand the degree of clogging of the secondary heat exchanger? Are there any secondary signs that help determine the condition of the heat exchanger??

Scale builds up on any bi-thermal heat exchanger. Limescale formed in the water circuit provokes local overheating and deposits in the heating circuit, which in turn leads to an increased deposition of limescale in the water circuit. The drop in flow rate is already.

We launched the gas boiler Buderus Logamax U072-24K. After the DHW is finished, the sound of pouring water. When switching to heating in sec. 5 the noise stops. When working in DHW mode there is no noise. Is it supposed to be like that, or is there something wrong with it?? Boiler in operation for 5 months., The week we changed the pump (because of the constant sound of pouring water)? Current flow rate on the turbine. 8 to 8.4 liters per minute.

The reason for poor flow turned out to be trivial, the screens at the faucets are clogged (although I cleaned them just a month ago). One of the faucets (thermostatic) hasn’t been cleaned yet in 3 years and after removing it, I saw this. I understand it’s sediment from the boiler. After cleaning, the pressure returned to its previous level. What do you think?? Worth a strainer, flush and mains mechanical 5mcm.

Set the temperature of hot water on the boiler to use it without mixing with cold water, and I think that the unit will work until it is morally outdated. It is necessary to put a dirt trap after the boiler.

Can you advise Buderus 072 fan modulation synchronously modulation burner during operation? Or the modulation only in the form of setting a step parameter depending on the length of the chimney?

If I’m not mistaken, it’s modulating. The current speed at a given moment can be seen in the service menu, parameter 2.9b.

In the automatics Logamatic 4211, I can not turn the STOP mode. I set the days, the room temperature, press AUTO. But the boiler has stood for 24 hours and never turned on. There’s one thing I don’t like. The room temperature is set, but when I start flipping through the menu, it says that the room temperature.0! Although when I look where the temperature setting, the temperature is what I set. To check, put the temperature higher than it was in the room, to check the performance. And nothing. What is the problem? Oh, and one more thing. The outside temperature is displayed (I have an external temperature sensor), but the inside temperature is nowhere to be seen. In MEC2, must be a temperature sensor, if I am not mistaken or it only works when the MEC2 is in a wall mount? BFU-no. MES2 is in 4211. What’s the problem?? At first, the type of reduction was OFF. Then I turned on LOWER. Or maybe you need to connect the BFU? Although MEC2 is also designed for this. Where is there a description of how to do it right. Heard something about the freezing temperature threshold, although I have not changed anything in this value, maybe there is a question?

Need a boiler. Gas, single-circuit, with a closed burner, wall mounted, 24 kW, with the possibility of connecting cascade. tell me the model?

We connected and put into operation Logamax U034 double boiler. With a long flow of hot water. the pressure in the heating system is dropping. The impression is that somewhere is squeezing water from the heating circuit into the DHW circuit. advise where to dig and what it may be? The system is filled from the same plumbing pressure 1.5 no more. When the hot water outlet is open, the pressure in the DHW circuit is naturally less. The tank is normal. In the absence of hot water extraction pressure practically does not change from the temperature in the heating system, and at long extraction (half an hour or an hour) falls to 0.

Close the cold water inlet to the boiler and open the hot water tap. Start the boiler and observe. (1.5 atm. in the water supply. You should have said right away about this anomaly, the norm is considered 3-5).

And by controlling the umbrella you can regulate the temperature of water in the boiler? Boiler Buderus Logomax 072.

Yes, according to Opentherm. The minimum temperature is 21 degrees. When set lower. heating stopped. But here’s the kicker. Earlier the temperature in the boiler by the boiler bus did not give. Therefore, if you want to see the actual temperature, you need an additional sensor Zont DS1820.

Is it possible to connect to an automatics logamatic 2107, which already has a pump group for the radiator circuit, 4 more pumps to run on automatic as the main, we want to split the heating to separate circuits.

You can, but only via a magnetic starter. Otherwise the relays in the automatics will burn out.

Tell me, to U052, as I understand, without additional. remote control can not be screwed to the weather? What is the minimum set of remotes required for this?

Control Module RC200 (7738110073) and the actual outdoor temperature sensor FA (05991374).

In operation wall mounted boiler U052-24. With the hood removed and the control panel mounting screw unscrewed, it is impossible to tilt it forward because of the short gauge hose (correspondingly, it is impossible to unscrew the back cover of the control panel). As far as I understand, you can only get to the terminals by disconnecting the hose from the pressure gauge. But if the system is pressurized, how then?

The pressure gauge is carefully pulled out of the front cover of the control panel. It is fastened with two plastic petals.

The Logomax 52-24 started dumping water through the alarm, even at two pressure gauges. Even a couple of times the boiler itself raised the pressure to three, in general, look for faults?

That at a low pressure it begins to work, it seems to change it. If up to three boilers, then you have something with circulation. Well, and the expansion tank, it seems, too, to change (or it was pumped wrong).

Assembled and installed a boiler Logamax U052-24K, it operates when cooking hot water as a flow. In the instruction to the boiler mentioned the possibility of connecting a boiler of indirect heating. Need the same boiler on the cottage, but must be connected to the boiler indirect heating. In the store, consultants said that this boiler can not be connected to the boiler t. к. it is a two-circuit. Is it true??

You need Logamax 052-24. The Turbid single-circuit with an opportunity to connect the boiler. Also need a boiler sensor AS1.6 and desirable room regulator.

There is a malfunction on the boiler logamax u042 in DHW mode. I open the faucet of hot water, the water flows well, but the burner does not turn on immediately. This may last 30 seconds, then the burner turns on and heats water for 3-5 minutes, let’s say, then turns off again, at this point the boiler display lights up 2 bars on the heating circuit temperature sensor (after 3-5 seconds they go out alternately). Seconds 40-60 burner does not burn, in the presence of water flow, of course from the faucet is flowing already cold water. Then the burner lights up for the next 3-5 minutes. And t. д. All this time only the hot water tap is open. At the regulator is always set the temperature of DHW 45gr. What can it be? It feels like the burner is shut down by the heat exchanger overheat sensor.

If everything is OK in heating mode, it could be a flow sensor, temperature sensor. Probably for overheating in the heating circuit. Low flow through it.

I am now negotiating with a specialist who will install CO, CB and boiler in a private home. Wall mounted boiler. logamax U072 (single-circuit), indirect heating boiler, electric boiler Rusnit (as a reserve, if something happens to the gas boiler). The office has made an estimate for the purchase of equipment. In this estimate I have not found the safety groups (except for the safety valve for the boiler). To my question. Where is the safety group for the boiler buderus, they said that a safety group for this boiler is not needed.

Safety valve is built into the boiler, additional safety group is not required. But if during the operation of the electric boiler will be (overlapped), then an additional safety group is needed (If Rusnita does not have an emergency reset valve). See data sheet.

turn, heating, buderus, boiler

There is a house of 200 square meters, 3 floors. It is necessary to connect the heating. What boiler Buderus and a boiler to choose and what automation? What do I want: separate control of floor heating in the hallway and bathrooms (bathrooms 3 or 4, is it possible to regulate each separately), separate temperature control on each floor. This could be done with a temperature sensor on the manifold.

Boiler U052 or GB072, boiler SU160-200l, automatic control RC300 module MM100 on the 2nd and 3rd floor RC100/200. This can be done by servo drives on the manifold with a temperature sensor, t.е. Press a little overheated circuits, but the “total” temperature in the TP is better regulated by the boiler automatics (rc300mm100).

Water supply. well. The boiler Logamax u042-24k (under warranty) after almost a year of excellent work, in winter periodically displays an error: three blinking LEDs. Read in the manual: “Too rapid increase in the temperature of the mowing line supply (differential control). Heating mode stops for two minutes (2E)”. Now the boiler only works for hot water. The heating was turned off. The error is not blinking. But the heating of the water is not uniform: first the cold water goes a long time, then very hot, then cold again and then hot again. To equalize the temperature adjust the handle of the faucet in the bathroom. I called a specialist from the service organization, he said that such boilers can not be put on the well water supply, they do not work with low water pressure and periodically give an error, buy another machine. The passport does not say anything about the well and other things. Only the minimum and maximum pressure range is written. Pressure in the water system 2.4 bar. Worth of water accumulator for 100 liters. The sensor turns on the pump when the pressure in the system drops to about 1, 6. 1.8 bar. The pressure in the boiler is maintained between 1 and 2 bar. Can you advise what the cause may be, has anyone experienced similar problems?

Zebra on DHW. Low flow of water (turn on the tap with hot water, put a 3-liter can and measure how long it fills). 2E-most likely clogged sump in the heating return.

information on gas boiler models: Characteristics, operating features, accessories, controls and adjustments, troubleshooting.

Gas-fired boilers are the optimal solution for heating almost any room. They are easy to use, small in size and have a long service life, so they are equally suitable for both private homes and apartments.

Working On A German Buderus Boiler

Any gas boiler has 3 main components:

Depending on the model, the boiler may have different optional equipment, such as a pump, fan, expansion tank, safety valve, electronic control system, diagnostics and protection. If the boiler has such additional elements, then it can be quite considered a miniboiler, which operates fully automatically. It independently maintains the temperature set by the program, controls all internal processes, and in case of an accident it shuts off the gas supply and turns off.

The principle of the boiler

To understand how a gas heating boiler works, you need not only to know its structure, but also to understand what programs and functions are laid in it. In its work the boiler is guided by the readings of the sensors. It determines the need for hot water with the help of built-in electronics and triggers the operation of the gas control valve. After that the gas burner, which heats the water in the heat exchanger to a certain temperature, and the circulating pump, which immediately distributes it through the heating system. When the temperature in the system reaches a predetermined value, the boiler switches off the burner and enters into a stand-by mode. When the temperature in the heating system drops to a certain value, the boiler turns on the burner again and the cycle repeats.

All single-circuit boilers work according to this scheme in heating mode. Two-circuit boilers perform exactly the same cycle, but its work can be interrupted by the hot water system (DHW). Two-circuit boiler has a more complex system of water treatment, since it performs two functions at once:

In addition to the main heat exchanger, it has a second circuit (high-speed heat exchanger), which is designed for hot water preparation. Two-circuit boiler can operate in 2 modes:

If the boiler operates in the winter mode, the water is heated in the primary heat exchanger and pumped through the heating system. When you open the hot water tap in the boiler, the flow sensor is triggered. It sends a signal to the control board, which switches the three-way valve from heating to DHW mode. As a result, hot water from the main heat exchanger does not go to the batteries, but remains in the boiler.

It begins to circulate in a circle, passing through a secondary heat exchanger and heating water for DHW.

The secondary heat exchanger is plate, so the water is heated almost instantly, and we instantly get hot water at the tap. This occurs until the hot water tap is closed. After shutting off the water, the flow sensor reports this to the circuit board, and it switches the three-way valve to its original position, and the heated water from the primary heat exchanger flows back into the heating system.

From the description it can be seen that the principle of the gas boiler does not allow simultaneous operation of the heating and hot water supply. However, there are already special heat exchangers that can do this (they will be described below).

The device of the gas boiler

Boilers of different manufacturers may vary in design and layout of elements, but they all have a typical scheme. We will consider it on the example of a two-circuit boiler (as the most complex).

  • gas valve for fuel supply to the burner;
  • gas burner;
  • ignition unit;
  • ignition electrode;
  • flame control sensor;
  • gas combustion chamber;
  • Primary (main) heat exchanger;
  • fan;
  • Exhaust gas traction sensor. manostat;
  • water temperature sensor in the primary circuit;
  • emergency temperature sensor of the primary circuit water;
  • expansion tank;
  • circulation pump of the primary circuit;
  • heating system filter;
  • water pressure sensor in the heating system;
  • water make-up valve of the heating system;
  • safety valve of heating system;
  • three-way valve;
  • hot water heat exchanger (DHW);
  • bypass;
  • DHW flow sensor;
  • DHW filter;
  • water drain cock;
  • electronic control unit (control board);
  • regulators of heating and DHW system temperature;
  • Mode switch (summer, winter).

As can be seen from the large number of various sensors, half of the devices monitor the system and allow the boiler to operate safely in automatic mode. In addition, the boiler has standard fittings for:

  • fuel supply to the gas valve;
  • water supply to the heating system;
  • Return water inlet from the heating system;
  • The main element of the boiler is the burner, the cold water inlet for DHW;
  • outlet of the heated DHW water.

To understand the operation of the boiler more clearly it is necessary to consider each component separately and determine its function and purpose. It is worth to remember that “unnecessary” and “unimportant” parts in the boiler does not exist, and the failure of even one of them will lead to a breakdown or malfunction of the boiler. Below we will analyze in detail the most important blocks of the gas boiler, and what elements it includes.

Gas burner and smoke removal system

The main element of the gas boiler is the burner. In modern boilers, it is modulating, that is, it is able to change the amount of gas consumed. This function reduces the gas flow during ignition and at the beginning of the heating cycle (heating of the heat exchanger gradually). Then it increases gas supply when approaching a preset temperature and maintains it. When the water heats up and the cut-off time is approaching, less gas is supplied. This reduces gas consumption by up to 15% and reduces the number of switching cycles, thereby extending the life of the boiler.

Preparation and supply of fuel is carried out by a gas valve. During the operation the fuel supply is regulated by a stepper motor. It is controlled by microprocessor of electronic board according to the program set in the factory. You can set the desired temperature for heating and domestic hot water via the control panel.

Also on the burner is located the ignition electrode and the flame control sensor. The burner is located in a closed combustion chamber, which ends with a waste gas outlet. At the outlet there is a fan for forced smoke evacuation. In front of the fan there is a draught sensor. monostat, which will immediately shut down the boiler if the smoke is not drawn out. The manostat is often triggered in extreme cold, when condensate freezes in the exhaust pipe and the exhaust gas outlet is blocked.

Heat exchangers

Heat exchangers are divided into two types: primary and secondary. The first one is installed above the burner, since it heats the water of the first (heating) circuit. It is a set of copper tubes in which water circulates with the help of a flow pump. To increase the usable area and to quickly heat water, copper plates (fins) are pressed on the tubes.

A secondary heat exchanger is needed to heat DHW water. It has distinctive features that allow instant water heating. The exchanger looks like a set of plates, between which the water of the primary and secondary circuit circulates separately. When the hot water tap is opened, the water in the primary circuit is not going to the heating system, but is redirected to a secondary heat exchanger. Thus, instead of heating the radiators, the DHW circuit is heated. The peculiarity of double boiler is that the heating and DHW heating can not be made simultaneously. In domestic conditions it is practically not noticeable, since the consumption of hot water is insignificant compared to the operation of the heating system.

When the daily water consumption is high and competes with the heating system, the double circuit boiler with a bi-thermal heat exchanger is used. They are characterized by the fact that they have only one heat exchanger, which is located above the burner. Its design is a bit more complicated, and within the tubes of the main circuit are the tubes of the DHW circuit. It turns out that the burner heats only one heat exchanger, which simultaneously contains the water of the heating system and DHW (that is why they call it bitermic).

D.H.W. System

The main difference between double-circuit boilers is the hot water system (DHW). It allows you to get hot water almost instantly. For this purpose, the boiler has a secondary DHW circuit, which consists of a plate heat exchanger, water flow sensor and three-way valve. The main sensor that controls the process of starting the secondary circuit is the flow sensor. When you open the tap it sends a command to the control board, and that, in turn, to the three-way valve that closes the water supply to the heating system and directs it to the DHW plate heat exchanger. As a result, hot water, which is heated in the main heat exchanger, with the help of a pump begins to circulate in a “small” circle inside the boiler, passing through a DHW heat exchanger and heating water in it.


It connects the forward and return piping of the main circuit. There is an adjustable bypass valve on the bypass, which opens when a critical pressure is reached, and part of the water flows from the straight pipe to the return pipe. The valve ensures that there are no hydraulic shocks when the pump is turned on and limits the maximum speed of water circulation in the heating system.

The expansion tank

When the water heats up, it begins to expand in the heating system and to compensate for the excess pressure, expansion tanks are installed. They are present at all boilers, but may differ in form and size (depending on the boiler power).

The expansion tank consists of three parts:

The tank during the operation of the heating system due to the membrane levels out the pressure changes, so during the operation of the boiler pressure remains unchanged.

Control board and sensors

Whatever the device of the gas boiler, it necessarily has a board (block) control. It allows you to set the necessary modes of the boiler, monitors and analyzes information from sensors, performing automatic control of all processes in the system. On the board itself, there are no adjustments and settings, all settings are made in the factory. The only thing the user can change is to connect an external temperature sensor. If there is no sensor, the control system is guided by the temperature of the water in the system and when it cools down, it starts the boiler.

If you connect a sensor, the boiler control system begins to orient itself on it. To connect the external thermometer on the board to remove the jumper and connect the wires of the control device instead. There are simple membrane sensors, which only set the maximum and minimum temperature in the room. There are also more complex electronic sensors, which can indicate not only the temperature, but also the time of switching on, off the boiler. For example, the boiler will not run while you’re at work, but will turn on an hour before you return.

The normal operation of the boiler, its reliability depends on a variety of sensors and control systems such as

  • sensor of gas pressure in the system;
  • flame control sensor;
  • Exhaust gas draught sensor;
  • sensor of water temperature in the primary circuit;
  • emergency sensor of water temperature of the primary circuit;
  • sensor of water pressure in the heating system;
  • safety valve of the heating system;
  • DHW flow sensor.

Thanks to them, the boiler can operate independently for a whole season without stopping and breakdowns.

Unfortunately, in the process of operation there are problems not related to the boiler, but arising from external factors. For example, if the house gas is turned off, the boiler will instantly detect it and shut down. It will have to be restarted manually by performing special commands.

In case of errors or accidents in the boiler operation, it immediately stops working and sends a conditional signal. In models with electronic monitor an error code is displayed as a set of numbers or letters. In devices with analog (mechanical) control the error is indicated by blinking of indicators.

In the passport of any boiler there is a table with error codes, their deciphering and instructions on how to reset (eliminate) the problem. Such tables are easy to find on the Internet, the more so that error codes of almost all boilers are the same.



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