Combi boiler water pressure dropping

Welsh_Totster

Our ferroli combi boiler needs re pressurising every day as it drops to almost nothing. What's likely to be the cause and would it be an easy job to fix? Will be getting a service on it asap.

ariba10

You must be loosing water somewhere,

Either a small leak or you are setting the pressure too high when you fill it, and the excess water is being vented, as the system heats up.

keystone

Pressure when cold should be iro 1 bar.

Pressure when hot should be iro 2 bar.

If when hot pressure rises to iro 3 bar the PRV will lift to relieve the pressure.

If they have lifted inevitably carp gets in the seating and it doesn't reseat properly and then it starts passing.

So check the PRV drain to see if its wet or dripping. If so get PRV checked.

If not get the expansion vessel checked as it either needs recharging or the diaphragm is knackered.

Cheers

Welsh_Totster

when cold and we re pressurise it we let it get to 1 and thats it. we then put ther heating on for a few hours and by the next day its back down to zero. Will look into what youve suggested thanks, and get it serviced too!

gas4you

Sounds like the expansion vessel either needs re-pressurising, or is knackered and needs replacing.

If you can find the car type valve on it, press the pin. If water comes out it is knackered, if nothing (no air or water) it needs re-pressurising, which will (should) be included in the service.