Water heating systems operate when there is pressure inside the mains and without it. This is due to the design features of the heating complex as a whole and its individual elements. Pressure allows you to increase the efficiency of the equipment and requires the installation of pipelines, which are called closed circuits, by qualified specialists. The operation of open heating systems (by gravity) is gradually becoming a thing of the past, but, due to simplicity, still finds application in everyday life.
What pressure in the boiler is considered normal
The value of this indicator in the heating system depends on the purpose of the mains and the heat sources used. For example, for a high-rise building, a pressure of 7-11 atmospheres (atm) is considered normal, and for an autonomous highway of a two-story private cottage, depending on the design of the boiler heat exchanger, a value of up to 3 atm will be acceptable.
The value depends on the equipment and the strength of the coil in which the coolant is heated. Modern household gas units are equipped with durable heat exchangers that can withstand 3 atmospheres. Solid fuel equipment manufacturers recommend not exceeding a value of 2 atm.
The given values show the maximum value for which the boiler is designed. It is not at all necessary to operate it in this mode. Moreover, when heated, an increase in pressure occurs. An average value will be sufficient, which will ensure the required performance of the unit and radiators.
To determine the operational value, the recommendations of the manufacturers of the used boiler and installed heating devices are taken into account. All of them are reduced to indicators from 0.5 to 1.5 atm. The pressure value of the autonomous system, which is within these limits, is considered normal!
ATTENTION! Some users of modern systems argue that the higher the pressure, the greater the efficiency of thermal equipment. Studies show that the differences between operation at 1 and 2 atm are insignificant when it comes to stand-alone systems. In this case, the wear of the connecting elements of the line increases by an order of magnitude!
The pressure fluctuations that occur during operation in the heating mode will less affect the nodes and devices with a lower value. Operation at 2 or more atmospheres will require additional load, as well as periodic operation of the closed expansion tank and safety valve.
Reasons for deviation from the norm
The need for heating arises throughout the entire cold season, and this is 6 months of continuous heat supply (for middle latitudes). For such a period of time, the system must uninterruptedly give out the necessary thermal power, and the pressure in the line must have a constant value. In practice, this does not always happen like this. The influence of external and other factors causes interruptions in the operation of heating equipment. Consider the reasons that affect the parameters of autonomous systems.
Why pressure indicators are falling
The first and main reason for reducing the operating parameter is a coolant leak at the joints of pipelines with heating equipment. To temporarily eliminate this drawback, a booster valve is used. If not, refuel the main with coolant as pressure drops from the water supply network or well. Such measures will allow to temporarily normalize the pressure force.
To completely eliminate the disadvantage, you must:
- detect a leak;
- turn off the heat source;
- drain the coolant on the main section, having previously blocked the flow of water;
- repair the required unit;
- pump water, turn on the boiler.
IMPORTANT! In the absence of the possibility of draining the coolant in a separate section, in autonomous systems, the line is emptied, and after the malfunction is eliminated, they are refilled!
Leak detection is possible if there is a wet spot or droplets on the pipe connections. In cases where it is not possible to see the leak, first, increase the pressure to 3 atmospheres and turn on the circulation pump. If this does not help, then drain the water and pump air. The place of air leakage is determined by sound, and make sure with the help of soapy water, which will indicate the exact location of the defect.
The cause of the pressure drop may be the wear of the heating equipment, the appearance of scale in the heat exchanger and the pipes of the system. Another little-known reason for the decrease in operating parameters is a decrease in temperature. When the unheated house cools down in the cold season, and the coolant is cooled accordingly, the value of the parameter drops by 0.5 atm or more. In such a situation, the lower limit of the value is maintained at the level of 0.9-1.0 atm and to prevent freezing of the coolant during periodic operation of heating.
Why pressure rises sharply
A malfunction of automation, providing automatic filling of the line, is often the cause of rapid changes in parameters. In addition, slowing down the circulation of the coolant through the pipes leads to overheating, and accordingly to an increase in pressure. The cause may be air congestion, as well as the presence of dirt in the filter or other components of the system.
To identify the reasons for the growth of the controlled parameter, all emerging factors are compared, and then draw conclusions. A simple method to eliminate a sharp increase in pressure is to vent excess coolant, force the pump to turn on, then pump water, if necessary, to the set value. Repeating the procedure with a smaller amplitude of jumps and gradual equalization of the controlled parameter, indicates the elimination of air congestion.
The impossibility of eliminating the cause by this method indicates the presence of "impenetrable" dirt, which interferes with the normal operation of the boiler. To eliminate this reason, first clean the filter, and if it does not help, a heat exchanger. The cleaning method is applied both mechanical and hydraulic. It is important not to damage the internal cavity and connecting pipes.
REFERENCE! During operation of solid fuel boilers, especially during ignition, the pressure jump can change the value by 1-1.2 atm! It is important to compare the change in the controlled parameter with an increase in temperature. The direct dependence of the compared values indicates the need to slow down the ignition of the unit.
Monitoring and eliminating pressure surges in the heating system
To obtain objective information about the operation of the entire highway, it is equipped with several pressure gauges. The number of thermometers is always not enough for an objective assessment of the operation of individual sections. Comparing the data of measuring instruments in various modes, the user can independently identify the place of unstable heat transfer and a possible malfunction.
The reliability of the entire heating system is achieved by installing:
- a membrane expansion tank, which, with an increase in pressure above 2 atm, compensates for its further growth;
- a safety group consisting of an automatic air blower, a pressure gauge and a valve set to a specific value, after which it opens and relieves excess pressure.
The expansion tank is installed on the "return", and the air vent with the rest of the devices at the upper point of the "supply" line. The presence of these attributes eliminates the possibility of pipeline ruptures and damage to the boiler heat exchanger.
ATTENTION! When installing an explosion-proof valve, its performance is checked by the method of artificially creating high pressure!
After familiarizing yourself with the operating parameters of the system pressure, each user of autonomous heating can independently diagnose the cause of the malfunction and, if desired, eliminate it.
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