Worcester-Bosch 240 Combi Boiler - Pressure Problem

[d.a.mcfarlane]

Hi,

I recently moved into a new flat with a Worcester-Bosch 240 Combi-Boiler installed. At first it was fine, but now the pressure seems to have fallen considerably - when the boiler is off the pressure gauge reads 0 and when switching on the central heating this only rises to about 0.2 bar (and then slowly rises but only about as far as 0.5). The boiler is also noticably noisier when starting up - but the heating and hot water seem to work as they always did.

I know nothing about the boiler (i don't even have a manual) and have no experience with central heating systems - if someone could offer some advice on this I would be very grateful.

Cheers,

David

 

[Gees]

I'm NOT a heating engineer but as far as I know, after having several combis in my time, the system should be at 1 bar when cold and will usually rise to 2 bar at full heat. Thia may be wrong but have you tried filling to 1 bar and see what happens. If the pressure drops over a period of time find the leak!!!

 

[sifu]

In case you don't know, there will be a hose, usually chrome just below or near the boiler. On one end of this is a non-return valve, the other end there will be a tap of some sort. The tap may have a handle a bit like a washing machine tap, or a flat bladed screwdriver slot. Turn this tap so it is parrallel with the tap body and the pressure should go up. Put the pressure up to between 1 and 1.5 bar; 1 bar if the boiler is at the highest point in the system, 1.5 bar if it is at the lowest point (this allows for static head from the rads above). Then turn the tap off. The system should quieten down.

Sifu

 

[Ant]

If after doing as suggested above the pressure drops again then you must have a leak somewhere. There is an overflow/vent pipe coming from the boiler usually to an outside wall - check to see if water is coming from this. It is a pressure relief valve and opens to stop the boiler going in to meltdown - water from this often suggests a leaking pressure vessel in the boiler. If this is OK then check around all the pipework and rads etc for signs of water leaks.