what pressure should my boiler be at?

If your system has a pressure guage then you have a sealed heating system. Sealed heating systems require the pressure to be above a minimum threshold for the system to work and below a maximum threshold for them to work properly.

The generally accepted industry range is between 1 and 2 bar. In this article, we will explain more about these thresholds, about correct operation and any problems that need to be resolved.

different types of pressure guage

There are many types of pressure guage commonly found in heating systems. There are guages showing numbers, guages without. Guages showing a green and red range. There are digital guages. Some systems have more than one guage, where this is the case, the pressure should be the same or very similar throughout the system, depending on the location it is installed.

So if one of the guages shows a difference in pressure when at the same height then you may have a faulty or inaccurate guage. In most domestic heating systems numbered gauges will showing in the range upto 4 bar.

continually dropping pressure

If your pressure drops continually and you require to top up frequently, then your system has a leak. The source of the leak can be anything from a pin hole in the radiators, microleaks from valves, a pressure relief valve discharging due to debris and so on.

If your drop in pressure takes a period of several weeks, then you may have a very slow leak, these can resolved by finding any valves or nuts that have signs of leak and re-tightening, or a last case resort placing leak sealer into the system.

continually increasing pressure

If your pressure rises continually and hits the red zone usually at 3 bar even though you don’t have the heating system on, then your filling loop may be faulty or you may have accidentally left the valves in the open position. If the rise is rapid then this is likely the case.

If however your system is rising gradually and not dropping, then it’s possible the filling loop valves are faulty and letting water through. You can disconnect the loop to see if this is the case.

correct guidance for pressure based on our experience.

There may be many different opinions on what is the correct pressure, however based on average of most heating systems, ie anything up to 3-4 bedroom houses with maximum 3 floors. Aiming for 1.2 bar is our best practice. This allows the system to remain between 1 and 2 during operation and when the system is off or cooled down.

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