Why does water boil in a heating boiler. What are the advantages of an open heating system? Scheme of installation and principle of operation. Water circulation in the heating circuit is disturbed

stroy-aqua.com

After the reconstruction of the heating system, the boiler “boils”: what to do

Good afternoon Yesterday, we installed 2 additional radiators (white aluminum) in the heating system in a private house, installed, opened the valves, let water in, and as the radiator filled with water, air was bled through the outlet hole as usual. After the work done, the pressure in the system decreased and, as usual, water was added from the central water supply system (our house is connected to a water supply system that runs next to the house and we add water to the heating system from central system water supply, everything is connected so that he opened the valve - the water went). After all this, the boiler began to heat up and boil very quickly (in our house there are 3 circuits in the heating system, through which the first and second floors of the house are heated, each circuit is supplied with a pump (3 pcs.) And one pump is put in the return line. So here, all the pumps are working, the air in all the radiators is bled, and the boiler continues to heat up very quickly, literally from one firewood thrown in. I beg you to help in any way you can, I have been suffering for 2 days, I don’t understand what is the reason.

Unfortunately, knowing almost nothing about the heating system in your home, we cannot help with specific advice. It's like in medicine: in order to make a diagnosis, the doctor must get the results of the tests and examine the patient. And we are not even aware of the “anatomy”, you did not attach a diagram to the question. You need to know not only general arrangement heating appliances, but also the structure of the boiler room, the location of the air vents, etc. But, even knowing these parameters, trying to determine the nature of the problem in absentia is largely guesswork. There can be many local reasons for the system to malfunction, we will present the correct, in our opinion, algorithm for finding and eliminating them:

“... the boiler began to heat up and boil very quickly ... from one fire of firewood” - you probably meant that the temperature of the coolant rises much higher than the norm, the safety group may work, if one is installed. If before the system worked normally, and now, with a minimum load of the furnace, overheating occurs, there can be only one conclusion: the volume of coolant that passes through the water jacket of the boiler has sharply decreased. Some, quite a significant part of the liquid does not participate in active circulation. Let's look for reasons:
You write that after the reconstruction of the heating system, they supplemented it with ordinary tap water and bled air from the radiator. This is absolutely not enough. The fact is that you have replaced a significant part of the liquid, and tap water contains an increased amount of dissolved oxygen, which will be released gradually. You need to bleed air, and not only in the radiator that you replaced, but at least in the upper points of the circuits, and even throughout the entire system, you need at least two days after filling the system. Perhaps you supplemented the system after the work of the security groups, this increased the amount of air even more. By the way, supplementing the system with unprepared tap water is not the best solution also because it contributes to the formation of limescale inside the pipes and corrosion of steel elements. It is better to use a special coolant, technical distilled or at least boiled water (only the upper 2/3 of the volume of the vessel in which the boiling took place).
We recommend starting the search with the boiler room, it's easier. First of all, we advise you to check the presence of air in the circulation pumps, it could get there.

The screw in the center of the body is the pump blower. Unscrew it until a drop of water comes out.

It is necessary to check all air blowers available in the boiler room.

There should be more than one air vent in the boiler room, bleed everything.

The working pump should vibrate slightly, put your hand on it. There is a small chance that after repairing the system, chips, sand, and dirt could get into the impeller. Unfortunately, without removing the pump, it will not be possible to check whether it produces sufficient pressure.

While you are still in the boiler room, make sure that any valve on the line is not accidentally closed.

Next, we are looking for an airlock in the circuits. Low temperature any of the branches, the noise of a flowing liquid, gurgling in radiators - sure sign its presence. Experienced plumbers determine the presence of air by tapping: a dull sound is liquid, a sonorous sound is air. You will have to sequentially go around all the rooms and, paying special attention to slightly heated areas, bleed all the air valves. You need to start at the top of the system and move down.

A manual air blower (Maevsky crane) must be installed on each radiator

The cause of poor circulation can also be the general contamination of the system, primarily the batteries are clogged. heating appliance can be removed and blown out with compressed air or washed with a powerful jet of water.

The diagram shows that air vents, automatic on combs (5, 11) and Mayevsky taps (13) are placed on all heating devices without exception. This was done for a reason, but to eliminate situations like yours.

Based on site materials: http://stroy-aqua.com

fix-builder.com

What could be the reason

Dear Sirs!! Just tormented with heating. I will accept any advice and help. Thanks in advance.

Problem status:

1. When the coolant is heated (the pressure in the system is about 1 atm, the characteristics of the Grundfos pump UPS 25-80 180 mm 2 stage) the nearby circuits are gradually heated, the temperature in the boiler rises, but latest batteries still stay cold.

2. At some point, the nearby circuits also stop heating, and all the batteries become cold, and the boiler boils.

3. Then I achieve the desired result in different ways: I feverishly twist the central plug in the pump, releasing steam and coolant, turn the pump on and off, the last time it all lasted more than 2 hours, the process is generally uncontrollable. It seems that the pump works for itself and does not pump anything, I do everything at random.

4. Then at some point, everything suddenly breaks through, the batteries ALL instantly become hot, and the temperature in the boiler drops to 60 degrees. Then everything can remain and work well for several hours, or again after 2-3 hours the batteries can cool down and the temperature in the boiler rises.

Heating scheme

Unfortunately, you did not indicate whether this was the first launch after installation, or whether the heating system worked successfully before. We will assume that the design and installation were carried out correctly, the capacity of the compensation tank and the sections of pipelines were chosen correctly. The floor-by-floor wiring diagram you sent is simple and should ensure satisfactory circulation of the coolant. By the way, connecting a radiator on a ladder to a vertical line is irrational, the right decision would be to connect after the riser.

There may be several reasons for the fact that the temperature of the coolant periodically rises to a critical level, and the radiators remain cold:

Most often, such problems are created by a “plug”, air or mud. Air is especially actively released in the first month after filling the system; it is recommended to bleed it daily. The air blower (Maevsky crane) should be installed on each heating device. Automatic air vents are mounted at the upper points of the heating mains, in the boiler room, on the boiler itself, on the collectors (you, judging by the diagram, do not have them). Airing the system is the most common cause unstable heating operation. We recommend that you start the test with a thorough deflation, first at the top, moving down. If the air has to be bled frequently, and the pressure in the system drops, the tightness is broken somewhere.

An air blower should be installed on each heating radiator

hinder free current coolant can also be a mud “plug”. The first step is to check the filter, if any. Dirt and sludge can also be clogged by air blowers, especially needle-shaped ones (Maevsky taps).

Such a device combines the functions of an automatic air blower and a mud filter. Easy to maintain, allows you to ensure cleanliness and normal gas composition coolant

The reasons for the unstable operation of the heating may also lie in your circulation pump. Although, more often it fails immediately and permanently. Whether the pump is working can be checked by placing a hand on the body. A slight vibration should be felt. To begin with, we recommend checking and cleaning the electrical contacts. The reason may lie in the wear of parts of the electric motor or in the formation lime deposits, if unprepared tap water.

Theoretically, it is possible to unscrew the plug on a non-working pump and carefully turn the shaft with a screwdriver, it often helps (temporarily). You can get rid of deposits by dismantling the pump and washing it for a day in vinegar or a solution citric acid. But still independently disassemble and service circulation pump not having the skill is not easy. By the way, outside the heating period, the pump, in order to avoid oxidation electrical connections and shaft lock, should not be idle. Once every two to three weeks, it is recommended to turn it on for 15 minutes.

After a long period of inactivity, an air pocket may form in the pump. Before turning it on, check the presence of the necessary pressure in the system and vent not only the radiators, but also the pump itself

Rare, but still possible malfunctions in the electronics. Since the operation of the pump is controlled by the heating boiler controller, a failure in the program or incorrect operation of the sensors can adversely affect the operation of the system.

stroy-aqua.com

Pressure dropped, coolant and water mixed

Leonid, Orekhovo-Zuevsky District, Moscow Region

In a residential country house, a water supply and heating system is installed, including:

solid fuel boiler with the possibility of electric heating of the coolant;
boiler with the possibility of heating water, both from the boiler and electricity;
constant pressure pump;
required amount radiators.

All this is mounted in a closed system with forced pump for the coolant. Before winter season I drained all the water from the water supply system, also disconnected the pump from the system and left the drain taps, as well as the pump nozzles, open. When I started the heating (fired up the boiler and turned on the pump responsible for the circulation of the coolant), the coolant began to flow out of the open tap of the water system. After I turned off the tap from which the coolant flowed, the pressure in the heating system dropped to 0. The boiler thermometer reached 90 degrees, although working temperature usually no more than 60 degrees, and the temperature of the batteries was either very hot or slightly warm in one. I tried to restore pressure in the heating system, connected the pump and tried to pump additional coolant into the system (with the system in working condition). As a result, as soon as I turned on the pump (for additional pumping of the coolant), the coolant gushed out of the pipe of the pump of the water supply system. My question is as follows.

How can the coolant system be connected with the water supply system, because the coolant is toxic?
How to correctly switch from the integrated mode of operation of the heating and water supply system to the winter mode, without water supply?
How to restore pressure in the heating system?

Expert Answer

Hello!

All the factors you described indicate a depressurization of the water circuit of the boiler indirect heating. Such a breakdown is quite common, especially in conditions where water is periodically drained from the circuit, and it long time exposed to active corrosion. Of course, remotely one cannot be 100% sure that one is right, but all the facts indicate that the boiler heat exchanger corroded through and through:

The appearance of a coolant in the consumable branches of the water supply. Since the heating and water supply systems intersect only indirectly, that is, without mixing with working fluids, in good condition of the circuits, the ingress of the coolant into the water, just like vice versa, is excluded.
The pressure drop in the heating system occurs both due to air leakage through the water supply circuit, and due to leakage of the coolant. Of course, it is impossible to create the required pressure in an open circuit.
Uneven heating of the radiators of the heating system indicates the presence a large number air in the line, which contributes to the formation of air jams. It is possible that the cause of this phenomenon is the suction through the water circuit of the boiler.
With the NPD turned on, the pressure in the water supply system exceeded operating pressure in the heating system, so water could go into the coolant, but not vice versa. When you turned off the pump and drained the water, the obstacle to the coolant disappeared, so the antifreeze began to flow out. Additionally, this was facilitated by the included circulation pump.

This phenomenon can be eliminated by replacing or repairing the boiler. If you decide to purchase a new device, choose a device with a heat exchanger from of stainless steel, since even a copper circuit is prone to electrochemical corrosion, especially in systems with mixed materials (steel-copper-aluminum). To restore pressure, it will be enough to remove air from the heating system and make up for the loss of coolant.

The procedure for switching to winter mode in your case is completely correct and does not require adjustment. Finally, I would like to advise you to install additional Ball Valves in front of the consumption points, and insulate the lines and equip them with a heating cable. In this case, you do not have to completely drain the water from the system. In the future, it will be enough to close the installed valves and open the supply taps.

all-for-teplo.ru

The main reasons for the unsatisfactory operation of the water heating system. | ImhoDom.Ru

Subject to all the basic rules for installing a water heating system, its operation is not difficult. It is only necessary to regularly check the water level in the expansion tank and add water to the middle of the tank in a timely manner.

During test fires in properly arranged heating systems, all heating batteries are heated up simultaneously, water circulation in the heating system is normal. When not correct device the heating system, after filling it with water, when the boiler is kindled, a knock sometimes appears (hydraulic shocks in the boiler due to steam formation). At the same time, the main riser warms up very poorly. A common reason for this is the incorrect connection of the outlet pipe - supply to the heating system. If this pipe is welded to the boiler 2-3 cm below the upper plane of the boiler, then during the filling of the system with water of the intra-water boiler, air remains, which during the test fire will gradually be pushed into the main riser. With a weak firebox, after a while, all the air from the boiler is gradually forced out into the main riser, and from there into the expansion tank. must be welded on the same level with the upper plane of the boiler with a slight upward slope. With this installation of the boiler, air accumulation never occurs in it, which prevents tapping in the system during its operation.

If the upper and lower horizontal lines are not installed correctly, air often accumulates in them, which is why not all heating radiators warm up. For example, only the first three radiators closest to the heating boiler warm up. In this case, it is necessary to check with a level the presence of a slope of the upper hot horizontal line in view of its possible violation after the third descending riser. To eliminate the malfunction, it is necessary to correct the slope or install a valve in this place to bleed air from the system. After venting air through the valve, all heating radiators will warm up simultaneously.

Often, when installing a heating system, heating radiators are installed incorrectly. It is necessary that the nipples of the heating radiators, which are connected to the descending hot riser, be higher than the nipples on the side of the lower horizontal pipe. If the radiators are installed in violation of this rule, then air often accumulates in them, which is why some of the radiators do not warm up. To eliminate these shortcomings, valves (faucets designed by Mayevsky) are installed on the connections. After the air is released from the radiators, they will evenly warm up.

If the rules for installing a water heating system are not followed, then it is necessary to install certain valves to release air from the heating system. Air must be released regularly, sometimes even in front of each furnace, which makes it difficult to operate the heating system. expansion tank.

The appearance of knocks in a normally operating heating system indicates a cessation of water circulation due to a decrease in the water level in the expansion tank. In this case, the system should be replenished with water, after which the water in the boiler will stop boiling, water circulation will improve and knocks and noise will stop.

To maintain the economical operation of the boiler, as necessary, but at least once a month, it is necessary to clean the surfaces of the water boiler from soot and ash deposits.

imhodom.ru

Search for the cause of weak circulation of the coolant in a two-pipe heating system

Quite a lot of time has passed since the writing of the first article, and I, in anticipation of heating season 2011-2012, I decided to continue the cycle, especially since questions on the topic "I did the heating, but it does not work" continue to come.

Unfortunately, troubleshooting methods that do not lie on the surface are quite difficult to classify, and I decided to devote several small articles to the issue of heating system malfunctions. In this article, I would like to consider the problem of poor coolant circulation and uneven heating of radiators. I myself have never made mistakes like those described and, accordingly, here I will have to theorize a little.

Friends! Before troubleshooting your heating, please find the dirt filter and clean it! Perhaps after that there will be nothing to look for!

So, we have two-pipe heating. Let's consider one branch of this heating system serving, let's say conditionally, one floor. Here is her diagram. The water flow is shown by arrows.

The radiator located closer to the beginning of the branch, or to the boiler, is hot. This is the leftmost radiator. There can be significantly more radiators than shown in the diagram. For example, in my tiny house there are 3 branches. The longest has a length of about 25 meters and it has 5 radiators. The problem is that the radiators following the first are either completely cold or have a temperature much lower than that of the first. Moreover, the farther to the end of the branch, the colder and colder the radiators.

Our first radiator is hot (the hand can hardly stand it). We feel the next ones and find that all the radiators are hot, but their temperature decreases as we move along the branch. The latter is no longer hot, but slightly warm. We return to the first radiator, but we feel its bottom. We feel the bottom of all the radiators along the branch and find that the bottom of the radiators is much colder than their top. Even the first one.

We have water circulation in our heating branch. There is no air in the pipes. However, circulation is not fast enough. It is so weak that the water has time to cool as it moves from the radiator inlet to its outlet. Thus, the problem is diagnosed. We just have to find its cause and destroy it.

Do we have a circulation pump in the system?

If it is not there, then the problem of circulation acceleration is rather difficult to solve. It is necessary to put the boiler lower, it is necessary to increase the diameter of the riser, it is necessary to increase the diameter of the supply and return (horizontal lines) it is necessary to change the pipes to those in which inner surface smoother, you need to reduce the number of corners and make them obtuse, that is, 100 or 110 degrees. At least more than 90.

If there is a circulation pump, then ... solving the problem is not at all easier.

First, let's check if the pump is working. To do this in the general case is not as easy as it seems. A good circulation pump runs absolutely silently and without vibrations. You can only hear his work by putting your ear to him, and he is hot and you can get burned! I do not recommend you, dear friends, to risk your organs! Stock up on a medical stethoscope or just a tube large diameter(a piece of plastic pipe from the sewer with a diameter of 50 mm will do. Attach one end to the motor, and stick your ear into the other end. If you can hear the motor running, that's good!

By the way, if your motor is noisy, then it may have broken down and needs to be replaced so that it does not become painfully cold, but it is much more likely that air is seething in it. Maybe because of this, and the circulation is weak? In this case, turn off the motor and bleed the air. On any motor there is a means for this. And you can drain the water from the pump right while it is running, but this must be done very carefully so that it (the motor) does not break. As soon as water with bubbles stops coming out of the motor, the air release procedure must be stopped, that is, all holes must be screwed and added to the fresh water system, bringing the barometer pressure to the desired level.

Important note!

Re-reading my especially successful articles, and this article is undoubtedly quite successful, I noticed one inaccuracy. It concerns the descent of air on a running pump. The fact is that if your pump is especially powerful and creates a noticeable pressure, then the air bleed procedure can turn into airing the entire system. The point is that the pressure of the water is so great that air is sucked into the system, but the water does not pour out. It depends on the design and power of the pump. Possibly some other factors as well. In short, if bleeding is a problem in your system, be sure to turn off the circulator before bleeding. Extra caution won't hurt!

Is the pump running? Great! Is it possible to increase the circulation speed on it? Amazing! Let's zoom in and see what happens. If all the radiators have become evenly hot, then we believe that we simply have a too long branch and we used too thin pipes. It is possible that the pipes Bad quality or there are some obstructions to circulation in the form of a large number of corners, dents in pipes, and so on. Then we make a promise to ourselves someday to redo everything and live in peace. Well, maybe we change the circulation pump to a more powerful one. At the same time, we put up with increased electricity costs. What did you think? Is it so simple in big house live? Everything has to be paid for.

Suppose that increasing the circulation speed on the motor did not give anything.

We think it's a miracle! Something had to change, or the motor is faulty, after all. At least on the first branch radiator, the bottom should get almost as hot as the top. Let's assume there was no miracle! On the first radiator, both the top and bottom became hot, but further along the branch, the temperature still does not suit us.

I hope you have valves at least at the inlets of all radiators? We close the valve of the first radiator halfway and feel the rest. Did they get hotter? If yes, then we draw the following conclusion.

We have received such heating in which it is easier for water to pass through the radiator than to go along the entire branch. Why did it happen? Well, for example, because the diameter of the supply line (or return line, which is the same) is smaller than the diameter of the pipes for the inlet and outlet of the radiator. And it should be the other way around. The passage diameter of the lines must be greater than the diameter of the outlets to the radiators. If you use high-quality, for example, copper pipes, then pipes of no more than 15 mm inner diameter should be connected to the radiators. That's enough! Verified by your obedient servant!

After reaching this remarkable conclusion, we think that we got off lightly and live by regulating the circulation in our branch with valves. This, of course, does not add comfort. We change the valves to automatic thermostatic ones and we get, I hope, quite normal heating, which regulates itself. After that, we live in peace.

Next option. Both lines are hot, but the radiators are cold. In this case, the valves on the radiators are fully open.

By by and large this is also a miracle. In this case, the radiators cannot be absolutely cold. But if water rushes along the highways at the speed of a racing car, but does not enter the radiators, then this means that the problem is either in the radiators in all at once), or in the node connecting the radiator to the highway, and not necessarily the upper node, the input, so to speak . If the problem is in the lower, output node, then the effect will be exactly the same. In other words, if we block the radiator outlet, it will be absolutely cold, as if we had blocked the entrance. Why are control valves placed on top? Just so that you don’t have to lean too low to adjust them, and you don’t accidentally touch your foot.

If we consider malfunctions of radiators, then it is much more likely that the problem will be in only one of them, but not in all at once. In this case, you need to deal with one. Most likely the valve is the problem. That's where I think it's worth starting.

And the last. If we have an air lock or blockage in the middle of the line, then what do we get? All radiators and the line will be hot before blockage, and the supply and return lines immediately after the working radiator will be cold.

NOTE!

If this happened, this does not mean at all that the problem is somewhere near the working radiator. The problem can be anywhere in the supply and return line between the working radiator and the first non-working one. This is very important to understand! Understanding this crucial moment can save you a lot of time and effort. Yes, and money too.

I'm not too lazy to even draw a diagram

That's all. I hope this article has been useful to someone. As usual, I will be glad to comments and "accidents from life."

Dmitry Belkin

Article created 10/19/2011

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belkin-labs.ru

Comparison of systems with natural and forced circulation

A natural circulation heating system is a system in which the coolant moves under the influence of gravity and due to the expansion of water when its temperature rises. The pump is missing.

The heating system with natural circulation works like this. A certain volume of coolant is heated in the boiler. Heated water expands and rises (because its density is lower than that of cold water) to the highest point of the heating circuit.

It moves by gravity along the contour, gradually giving up its heat to pipes and heaters - while, of course, cooling itself down. Having made a full circle, the water returns back to the boiler. The cycle is repeated.

Such a system is self-regulating, as well as gravity, or gravitational: the speed of the coolant depends on the temperature in the house. The colder it is, the faster it moves. This is because the pressure depends on the difference in the density of the water leaving the boiler and its density in the "return". Density depends on temperature: the water cools down (and the colder it is in the house, the faster it happens), the density increases, the rate of displacement of heated water (with a lower density) increases.

In addition, the pressure depends on how far the boiler and the lower radiator are in height: the lower the boiler, the faster water overflows into the heater (according to the principle of communication of vessels).

Pros and cons of gravity systems

Realization of heating with natural circulation

Such systems are very popular for apartments in which an autonomous heating system is implemented, and one-story country houses small footage (read more about the implementation of heating systems in country houses).

A positive factor is the absence of moving elements in the circuit (including the pump) - this, as well as the fact that the circuit is closed (and, therefore, metal salts, suspensions and other undesirable impurities in the coolant are present in a constant amount), increase the service life of the system. Especially if you use polymer, metal-plastic or galvanized pipes and bimetal radiators, it can last 50 years or more.

They are cheaper than systems with forced circulation(at least for the cost of the pump) in assembly and operation.

The natural circulation of water in the heating system means a relatively small difference. In addition, both pipes and heating appliances, due to friction, resist moving water.

Based on this, the heating circuit should have a radius of about 30 meters (or a little more). Various turns and branches increase the resistance and therefore reduce the allowable contour radius.

Such a circuit is highly inertial: a lot of time passes from the moment the boiler is started to the heating of the premises - up to several hours.

In order for the system to function normally, conditionally horizontal sections of pipes must have a slope along the flow of the coolant. Air locks (read more about them here) in such a circuit are all collected at the highest point of the system. A sealed or open expansion tank is mounted there.

Water boils more often in a gravity-flow type heating system. For example, in the case of using an open expansion tank, sometimes there is not enough water in the system, and also if the pipes have too small a diameter or too little slope (due to this, the coolant speed decreases). It can also happen due to airing.

The speed of movement of water in a gravity circuit

The speed of water in the heating system is determined by a number of factors:

Heat carrier pressure.
The diameter of the pipes (the smaller the diameter, the higher the resistance, so it is better to use pipes with a larger diameter).
The number of turns and their radius, Optimal - the minimum number of turns (best of all in a straight line, and if they do exist, then with a large radius).
Shut-off valves: its quantity and type.
The material from which the pipes are made. Steel has the greatest resistance: the more deposits on it, the higher the resistance, galvanized steel - less, polypropylene - even less, so the diameter polypropylene pipes may be less than steel.

forced circulation

Schematic diagram explaining the operation of forced circulation

A forced circulation heating system is a system that uses a pump: water moves under the influence of pressure exerted by it.

The forced circulation heating system has the following advantages over gravity:

The circulation in the heating system occurs with much more speed, and, consequently, the heating of the premises is carried out faster.
If in a gravity system the radiators heat up differently (depending on their distance from the boiler), then in the pump room they heat up the same way.
You can adjust the heating of each section separately, overlap individual segments.
The wiring diagram is more easily modified.
Air does not form.

The disadvantages of such a system are also available:

It is more expensive to install: unlike the gravity model, you need to add the cost of the pump and the cost of valves to cut it off.
It is less durable.
Depends on power supply. If you experience interruptions in its supply, you need to get a source uninterruptible power supply.
It is more expensive to operate because pump equipment consumes electricity.

Selection and installation of the pump

There are a number of factors to consider when choosing a pump:

What kind of coolant will be used, what will be its temperature.
Line length, pipe material and diameter.
How many radiators (and which ones - cast iron, aluminum, etc.) will be connected, what will be their size.
Quantity and types of valves.
Will there be automatic regulation, and how exactly will it be organized.

When installing the pump on the "return", the service life of all parts of the circuit is extended. It is also desirable to install a filter in front of it to prevent damage to the impeller.

Before installation, the pump is deaerated.

The choice of coolant

Water can be used as a coolant, as well as one of the antifreezes:

Ethylene glycol. A toxic substance that can be fatal. Since leaks cannot be completely ruled out, it is better not to use it.
Aqueous solutions of glycerin. Their use requires the use of better sealing elements, non-polar rubber parts, and some types of plastics; Installation may be required additional pump. Causes increased metal corrosion. In places of heating to high temperatures (in the area of the boiler burner), the formation of a toxic substance, acrolein, is possible.
propylene glycol. This substance is non-toxic, moreover, it is used as a food additive. Based on it, eco-antifreezes are made.

Design calculations of all heating circuits are based on the use of water. In the case of using antifreeze, all parameters should be recalculated, since antifreeze is 2-3 times more viscous, has much more volumetric expansion, and lower heat capacity. This means that much more powerful (by about 40% - 50%) radiators, higher boiler power, and pump pressure are required.

When the temperature of antifreeze is exceeded, it decomposes. In this case, acids are formed that cause metal corrosion, and solid deposits are deposited on the walls of pipes and inside radiators and impair the movement of the coolant.

Antifreezes are also prone to leaks, they are the scourge of systems with big amount threaded connections. Its use is justified if the heating system can be left unattended for a long time on frosty days.

Ordinary water as a coolant is also not recommended: it is saturated with salts and oxygen, which leads to scale formation and corrosion of pipes and radiators.

Be sure to read more about the choice of coolant for the heating system. There are no trifles in this matter, but there are a lot of nuances.

The preparation of water for the heating system consists in softening it (read more here).

It happens like this:

Boiling: carbon dioxide volatilizes, some of the salts (but not magnesium and calcium compounds) precipitate;
Using chemical substances, the water softener for the heating system is magnesium orthophosphate, slaked lime, soda ash. All salts become insoluble and precipitate, to remove the residues of which the water must be filtered.
Distilled water in the heating system is ideal.

We hope that you understand the difference between natural and forced circulation. And you will choose the type of heating system that is best for you.

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The massive use of solid fuel boiler equipment poses special requirements for the owners of private houses. Despite the technical progress that has made it possible to bring modern solid fuel heaters to perfection, the operation of such equipment carries a certain danger. Failures in operation, violations of the operating conditions of heating equipment can cause equipment to fail at the height of the heating season. In the worst case, the occurrence of emergency situations with a running unit can result in serious injuries for the inhabitants of the house, damage to residential buildings.

In this aspect, one of essential conditions safe operation will protect the solid fuel boiler from overheating. Accurate compliance with the safety rules for the operation of heating equipment, the availability of capable automation and control devices, will provide you with the necessary protection against unforeseen situations.

Let us consider in more detail what the protection of boiler equipment against overheating is based on. What could be the reason for the boiling of the coolant in the heated circuit and what are the consequences of such a state of emergency.

Reasons for overheating of a solid fuel boiler

Even at the stage of selection and purchase, it is important to consider performance characteristics heating device. Many models that are on sale today have a built-in overheating protection system. Whether it works or not is another question. However, it is necessary to adhere to certain knowledge and skills, hoping to create an effective and safe autonomous heating system at home.

The reliable operation of the heating unit depends on the operating conditions. In case of obvious violations of technological parameters heating equipment and abuse standard rules safety, high probability of occurrence of an emergency.

For reference: If the temperature in the combustion chamber exceeds the permissible parameters, it can cause the boiler water to boil. The result of an uncontrolled process is the depressurization of the heating circuit, the destruction of the heat exchanger housing. In case of hot water boilers overheating may cause an explosion.

Warn possible Negative consequences maybe still at the stage. Proper piping of the heating device will be the key to your safety and reliable operation unit in the future.

Speaking in detail, in each case, the protection system of a solid fuel boiler has its own specifics and features. Each heating system has its pros and cons. Eg:

When it comes to solid fuel boilers with natural circulation of the coolant, it is necessary to take care of the safety and performance of the heating equipment even during installation. The pipes in the system are metal. Moreover, the diameter of such pipes must exceed the diameter of the pipes used for laying the circuit with forced circulation of the coolant. Sensors installed on the water circuit will signal a possible overheating of the coolant. Safety valve and the expansion tank play the role of a compensator, reducing excess pressure in the system.

A significant disadvantage of the gravitational heating system is the lack of an effective mechanism for adjusting the operating modes of solid fuel boilers.

Great technological opportunities for consumers are provided by those working with forced circulation of the coolant in the system. Already only the presence of the second circuit significantly increases the ability to regulate the heating temperature of the boiler water. The only negative in the operation of such a system is a working pump, which can make it difficult to operate the heating system with its work.

This is due to the fact that when the electricity is turned off, the pump ceases to perform its functions. Stopping the circulation process and the inertia of solid fuel heating boilers can lead to overheating of the heating unit. If the boiler equipment is not equipped, the situation with a power outage is fraught with extremely unpleasant consequences.

Effective protection against overheating of a working solid fuel boiler should be based on the mechanism for removing excess heat generated by the heating device.

What are the ways to protect heating equipment from overheating

Manufacturing companies are trying, in order to increase the consumer attractiveness of their products, to contribute to technical certificate boiler equipment any guarantees of its safety. The uninitiated consumer has no idea about the means of protecting the heating boiler from boiling.

There are currently the following ways to ensure the protection of solid fuel units used for autonomous systems heating. The effectiveness of each method is explained by the operating conditions of boiler equipment, and structural features aggregates.

In most cases, in the data sheet for the heater, manufacturers recommend using tap water for cooling. In some cases heating boilers on solid fuel are equipped with built-in additional heat exchangers. There are models of boilers with remote heat exchangers. A safety valve is used to prevent overheating. The safety valve is designed only to relieve excessive pressure in the system, while the safety valve opens access to tap water when the boiler overheats.

Important! In the presence of cast-iron heating devices, such a measure is fundamentally wrong. Cast iron heat exchangers are afraid of a sharp temperature drop. Supplying cold water to the circuit can lead to loss of integrity of the heat exchanger housing. (heated to high temperature cast iron will simply burst on contact with cold water).

Exceeding the coolant temperature of 100 0C creates an overpressure that opens the valve. Under the influence of tap water, which is supplied under pressure of 2-5 bar, hot water cold is forced out of the circuit.

The first aspect that calls controversial points regarding cooling with tap water - the lack of electricity to ensure the operation of the pump. The expansion tank does not have enough water to cool the boiler.

The second aspect that this method of cooling dismisses is associated with the use of antifreeze as a coolant. In the event of an emergency, up to 150 liters of antifreeze will go down the drain along with the incoming cold water. Is this protection worth it?

The presence of a UPS will make it possible to maintain the operation of a circulating pump in a critical situation, with the help of which the coolant will evenly diverge through the pipeline without having time to overheat. As long as the battery capacity is sufficient, the uninterruptible power supply guarantees the operation of the pump. During this time, the boiler should not have time to heat up to critical parameters, the automation will work, starting the water through the spare, emergency circuit.

Another way out of a critical situation is to install emergency scheme in the binding of a solid fuel unit. The shutdown of the pump can be duplicated by the operation of a spare circuit with natural circulation of the coolant. The role of the emergency circuit is not to provide heating for residential premises, but only to be able to remove excess heat energy in an emergency.

On a note: the installation of an emergency circuit can be replaced by the installation of a bypass, which will, in extreme cases, divert superheated boiler water to an expansion tank or heat accumulator.

Such a scheme for organizing the protection of the heating unit from overheating is reliable, simple and convenient in operation. special funds on its equipment and installation from you is not required. The only conditions for such protection to work are:

the presence of an expansion tank or storage tank in the system;
usage check valve only petal type;
the pipes of the secondary circuit must be of a larger diameter than the conventional heating circuit.

Conclusion

Assessing the technological capabilities of modern solid fuel boilers, one should think not only about its operating power, but also foresee the installation of protection elements for the entire system. Overheating of the boiler is a frequent and well-known phenomenon for the inhabitants of private houses. Using the available means to ensure protection will not only avoid emergency situations, but also extend the operation of the heating units. Everyone is free to choose the means and method of protection. It will be enough for one to install an electric generator, which, together with the UPS, will not allow the circulation of water in the system to stop. Other owners of a private house, on the contrary, will need to install a bypass or equip a spare, emergency circuit for safety reasons.

According to experts, installing a buffer tank or installing a bypass are the most effective ways to protect the heating system from overheating.

Note: in the USA and in European countries, the operation of solid propellant devices without a buffer tank is prohibited.

Dear Sirs!! Just tormented with heating. I will accept any advice and help. Thanks in advance.

Problem status:

1. When the coolant is heated (the pressure in the system is about 1 atm, the characteristics of the Grundfos UPS 25-80 180 mm 2 stage pump) the nearby circuits are gradually heated, the temperature in the boiler rises, but the last batteries still remain cold.

2. At some point, the nearby circuits also stop heating, and all the batteries become cold, and the boiler boils.

3. Then I achieve the desired result in different ways: I feverishly twist the central plug in the pump, releasing steam and coolant, turn the pump on and off, the last time it all lasted more than 2 hours, the process is generally uncontrollable. It seems that the pump works for itself and does not pump anything, I do everything at random.

4. Then at some point, everything suddenly breaks through, the batteries ALL instantly become hot, and the temperature in the boiler drops to 60 degrees. Then everything can remain and work well for several hours, or again after 2-3 hours the batteries can cool down and the temperature in the boiler rises.

Heating scheme

There may be several reasons for the fact that the temperature of the coolant periodically rises to a critical level, and the radiators remain cold:

Most often, such problems are created by a “plug”, air or mud. Air is especially actively released in the first month after filling the system; it is recommended to bleed it daily. The air blower (Maevsky crane) should be installed on each heating device. Automatic air vents are mounted at the upper points of the heating mains, in the boiler room, on the boiler itself, on the collectors (you, judging by the diagram, do not have them). Airing the system is the most common cause of unstable heating operation. We recommend that you start the test with a thorough deflation, first at the top, moving down. If the air has to be bled frequently, and the pressure in the system drops, the tightness is broken somewhere.

An air blower should be installed on each heating radiator

A mud “plug” can also interfere with the free flow of the coolant. The first step is to check the filter, if any. Dirt and sludge can also be clogged by air blowers, especially needle-shaped ones (Maevsky taps).

Such a device combines the functions of an automatic air blower and a mud filter. Easy to maintain, ensures cleanliness and normal gas composition of the coolant

Theoretically, it is possible to unscrew the plug on a non-working pump and carefully turn the shaft with a screwdriver, it often helps (temporarily). You can get rid of deposits by dismantling the pump and washing it for a day in vinegar or a solution of citric acid. But still, it is not easy to disassemble and maintain the circulation pump without having the skill. By the way, outside the heating period, the pump, in order to avoid oxidation of electrical connections and blocking of the shaft, should not be idle. Once every two to three weeks, it is recommended to turn it on for 15 minutes.

Good afternoon Yesterday, we installed 2 additional radiators (white aluminum) in the heating system in a private house, installed, opened the valves, let water in, and as the radiator filled with water, air was bled through the outlet hole as usual. After the work done, the pressure in the system decreased and, as usual, water was added from the central water supply system (our house is connected to a water supply system that runs next to the house and we add water to the heating system from the central water supply system, everything is connected so that the valve is opened - water has gone). After all this, the boiler began to heat up and boil very quickly (in our house there are 3 circuits in the heating system, through which the first and second floors of the house are heated, each circuit is supplied with a pump (3 pcs.) And one pump is put in the return line. So here, all the pumps are working, the air in all the radiators is bled, and the boiler continues to heat up very quickly, literally from one firewood thrown in. I beg you to help in any way you can, I have been suffering for 2 days, I don’t understand what is the reason.

Unfortunately, knowing almost nothing about the heating system in your home, we cannot help with specific advice. It's like in medicine: in order to make a diagnosis, the doctor must get the results of the tests and examine the patient. And we are not even aware of the “anatomy”, you did not attach a diagram to the question. You need to know not only the general location of the heating devices, but also the structure of the boiler room, the location of the air vents, etc. But, even knowing these parameters, trying to determine the nature of the problem in absentia is largely guesswork. There can be many local reasons for the system to malfunction, we will present the correct, in our opinion, algorithm for finding and eliminating them:

A manual air blower (Maevsky crane) must be installed on each radiator

The cause of poor circulation can also be the general contamination of the system, primarily the batteries are clogged. The heater can be removed and blown out with compressed air or washed out with a powerful jet of water.

There are several reasons why why is the water boiling in the boiler heating. For example, boiling is often the result of the fact that the liquid is heated in the boiler faster than thermal energy transferred to the heating line. This happens due to:

incorrect installation of the system;
the fact that there is no circulation (or its speed is low) - usually occurs in systems open type with expansion tank;
too much power of the device compared to batteries;
low amount of water in the line.

Low circulation rate

So, if the coolant circulates too slowly, then the coolant will not fully transfer the received heat and, as a result, the water in the boiler will boil. This only applies to systems where natural circulation liquid, and the angle of inclination or the diameter of the pipes is not selected correctly.

Note! In systems with forced circulation, this happens only in cases where the pump power is too low or it is completely out of order.

Little coolant

If there is too little water in the system or air locks, then this can also be the reason why the water boils in heating boiler. If there is an expansion tank, then you just need to add water. In other cases, it is enough to bleed the air (if there is no automatic valve, of course).

To increase the circulation intensity, it is necessary to re-equip heating system, and it is better, if possible, to put a circulation pump. In this case, even with the wrong slope of the pipes, the water will circulate properly.

High boiler power

If the power of the device is higher than the heat transfer of the line, this can also lead to boiling water. Especially if the air supply adjustment system is broken or absent altogether. There are several options for solving the problem:

put automatic system adjustments;
put a similar, but semi-automatic;
change the boiler (if it is made by hand);
increase the number of batteries;
increase their power.

Note! In addition, you can embed an indirect heating boiler into the main line - this device will “absorb” some of the energy from the water heating system and serve as a kind of heat accumulator.

Circulation problem

If you have a circulation pump, but the system is unstable, then the problem may lie in it. To check the operation, put your hand on the battery - if you feel a slight vibration, then the pump is working properly, if not, follow these steps.

Check and clean electrical contacts.
Check pump parts for wear and lime deposits (if normal tap water is used).
Finally, you can turn off the pump, unscrew the plug and turn the shaft with extreme caution. For a while this should help. Citric acid can be used to remove deposits.

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