Worecester 25CDICombi

[adavids]

Having problems with combi initially gaining pressure when central heating is activated. But once the central heating is switched off the pressure drops to 0.
No problems with the pressure when it hot water only.

 

[GforceJames]

The pressure should be between 1 and 1.5 bar when cold, and on operation it is normal for the pressure to rise by about 0.5 to 0.8 bar.
Try filling the system to the correct pressure when cold.

James

 

[ScottishGasMan]

Hey there

When you say the pressure rises when its on, how high does it rise when its hot? above 2.5 - 3?

If so It sounds like theres a problem with the expansion vesslle, causes the pressure to rise too high when hot, which causes a saftey valve to open releasing water from the system (you might see this water leaving a pipe outside the house near the boiler) and when it cools the pressure will drop back down below the origional to 0.

If so, prob needs the vessle recharged with a footpump, or worst case the vessle replaced (its the bigg red tank inside the boiler)

If the pressure is not rising above 2.5-3 when running then it may be a case of the system just loosing water, ie leaking some where (anywhere)

SGM

 

[gas4you]

Undo the 'car tyre' type valve on the expansion vessel. Press the pin in it, if water comes out it is knackered

If just air, search FAQ on how to recharge expansion vessel.