worcester24cdi combi Help and information on all topics relating to your central heating, air conditioning and ventilation issues.

[simon666]

Despite 2 british gas call-outs we are no nearer solving what was an infrequent intermittent problem to what is now about 4 times a week.
Upstairs the shower, which is directly linked to the combi , operates fine. However shortly after turning off the shower and turning on the hot tap at the bath basin , it is clear the boiler has shut down as only cold water comes through.
Down in the kitchen we see, every time this happens, a certain amount of water has dripped from the base of the combi unit (above seems to be where the pressure key is put in). When pressing the reset button, everything is fine again.
The pressure arrow drops very slowly over a few weeks period.
The gas enginerr said just re-set it evert time it happens. Clearly this is not the proper solution as something is clearly not quite right.
Any thoughts as to what is causing this to happen ?

[htg engineer]

hard to know exactly without seeing the boiler, but will try tell you what i think.

It sounds like when the water is turned off the microswitch or the diverter valve is sticking. With this happening the boiler will stay on when there's no water running causing it to over heat quite quickly. If the pressure rised too much this will cause a build up of pressure inside the boiler and it will discharge through the pressure relief valve outside.

I've seen alot of jobs where plumbers dont check the pressure relief valve for water tightness. so when its venting to ouside it may also be leaking inside. Check the pressure relief valve connections.

Let me know how you get on, I will watch for your next post