Gas boiler pressure drops - reasons and solutions
If you want your heating boiler to function optimally, at which both fuel consumption and combustion efficiency were at the maximum level, then you have to find out at what level the pressure in the expansion tank of your unit should be. It is this structural element that is its most important component, regardless of the type of fuel on which the heating equipment operates.
It is impossible to imagine a normally functioning water heating unit without an expansion tank. At the same time, the pressure in it is the reason for the normal working process, in which thermal energy is efficiently transferred from the burning fuel to the coolant.
Often, service center specialists are faced with questions such as "Why is the pressure drop in my Navien boiler?" There may be a lot of reasons for this. However, in order to correctly identify them, it is important to understand the basic principles of the equipment.
Work principles
As you know, a liquid coolant expands when heated, which is due to the banal laws of physics. So that because of this there was no depressurization of the system, which would lead to a breakdown, the engineers invented such a design as an expansion tank. This is a reservoir that is needed to move excess water or antifreeze into it. After the temperature of the coolant drops, excess fluid returns to the system. This happens under air pressure.
Placement of containers in heating units
Today, there are 2 main variations of expansion tanks, depending on the space allocated to them in the system. Among them:
- Built-in closed container. Most new units these days are equipped with expansion vessels by default. The volume of the structure is selected depending on the size and performance of a particular boiler. If a significant load on the tank is expected, then its volumes should also be rather large.
- Open external tank. Such tanks are often used when the circulation of the coolant occurs under the influence of gravity. This design is an open tank that is mounted at the highest point of the entire heating system. The liquid displaced when the temperature of the coolant rises enters the open container. In this case, when the water temperature drops, the residues from the tank enter the system under the influence of gravity and atmospheric pressure.
Tank pressure
What creates the pressure in the expansion tank? This role is taken over by compressed air, which is located in a closed tank together with excess heat carrier. This design makes the system as stable and reliable as possible. The documentation that comes with the equipment contains all the necessary information regarding pressure indicators.
Typically 1 to 1.2 atmospheres is normal for most models. In this case, this indicator is measured in the absence of a coolant in the circuit. Knowing the optimal level in accordance with the documentation, you can always determine when the pressure drops in your Navien boiler.
Solving basic problems
Owners of heating equipment equipped with an expansion tank often face the problem of a pressure drop in this tank, which is important for the stable operation of the boiler. On various forums, you can find many questions like "What to do if pressure drops in the Navien boiler?" We will try to consider typical problems using the example of Baksi units, since the owners of this equipment often ask such questions. At the same time, the information below will definitely be useful to the owners of units of other brands.
A little about Baxi
One of the most common reasons why the pressure in the Baxi boiler drops is a coolant leak. If you use antifreeze, then be prepared for the fact that this substance very easily "finds" the slightest leaks. To fix this problem, it is necessary to detect and close the leak. After that, you need to pump up the expansion tank to the optimum pressure (1-1.2 atmospheres).
Often, the pressure in the Baksi boiler drops when the temperature of the coolant drops. When the unit is restarted, the readings tend to level out, reaching normal levels. Experts do not consider such fluctuations to be the norm, but at the same time they are not detrimental to heating technology. If the pressure continues to drop even after starting the system, it is recommended to contact the service center.
Often the pressure drop occurs due to the fact that over time the tank is simply "blown away" through a special nipple. In this regard, a reservoir is no different from a bicycle tire. What should be done in this case?
If you notice that the pressure in your Baksi boiler is dropping, then first of all you need to turn off the heater, cut it off from the water supply system and drain the water. After that, we pump up the tank using a car pump with a pressure gauge to control the pressure. You need to pump until the water stops flowing. After the coolant has completely flowed out, you need to continue pumping to a pressure level of 1 bar. Then we connect all communications to the boiler, bring the pressure to 1.2-1.5 bar and start the heating.
If the problem recurs after a while, then most likely the reason is in the nipple, and it just needs to be replaced. The cost of such a replacement is usually low.
conclusions
Obviously, many people face such a problem as the pressure drop in the Baxi boiler and units of other brands. Nevertheless, if you correctly approach the issues of diagnosing the cause of the malfunction and do everything according to the instructions, then you will be able to quickly return your heating system to working capacity.
