Just had a plumber out and he replaced the expansion vessel, prv and valve, however, the boiler is continuing to lose pressure. Plumber says if this is the case the head exchanger is pin holed or there is a leak on the heating system either at radiators, or underfloor heating. Does this sound about right, as if this is the case I am concerned the first work may have been unnecessary?
Logic combi boiler losing pressure
- Thread starter Laine
- Start date
This can be a number of things.
Are you saying you have to keep filling it, because the pressure drops below the minimum working pressure and the boiler trips out and you have to refill it again?
This usually means a leak in the system. Are you finding air in the highest radiator in the house that has to be removed by bleeding the radiator?
Or is the boiler "venting" water because you're replacing too much? Put a pot under the vent tube outside the house and see if that collects any in 24 hours.
If it's a slow leak it's usually from one of the radiators, this can be unnoticed as the water evaporates as it drips out.
Check all the bleed screws and valves.
A remedy for pinhole leaks anywhere in the system, is "Sentinel," which is "Radweld for central heating." It is often a cure.
Are you saying you have to keep filling it, because the pressure drops below the minimum working pressure and the boiler trips out and you have to refill it again?
This usually means a leak in the system. Are you finding air in the highest radiator in the house that has to be removed by bleeding the radiator?
Or is the boiler "venting" water because you're replacing too much? Put a pot under the vent tube outside the house and see if that collects any in 24 hours.
If it's a slow leak it's usually from one of the radiators, this can be unnoticed as the water evaporates as it drips out.
Check all the bleed screws and valves.
A remedy for pinhole leaks anywhere in the system, is "Sentinel," which is "Radweld for central heating." It is often a cure.
Yes pressure drops below minimum. Yes also finding air in loft radiator. Thanks for the reply very helpful.
Check all your radiators and remove any air, this will reduce the pressure in the system. If there's a bit of a leak, you don't want to re-fill it too high.
Wait until the system has been off for fifteen minutes. The pressure will be dropping during that time. Then check the pressure. It only needs to be just over 1 bar for most systems, when it's off. If it's more than that, then some systems have a pressure relief valve that you can manually open. But the easiest way to reduce the pressure, is to just bleed some water out of a radiator until you get the desired pressure, it won't be much.