CH switching off after couple of minutes

[kenbo9]

I have a Valiant Turbomax Combi Boiler which has worked well until my latest attempt at decorating which involved taking and putting back on a radiator.

Before switching the heating on I had to refill system as it was at zero. As instructed I did this to just below 1.5 bar. Incredibly radiator (and others) heated up but I noticed that the pressure quickly fell to zero. I refilled, switched on and radiators again warmed up but CH switched off after a couple of minutes. It has continued to do this. Hot water supply is working perfectly. Pressure appears to have stabilised.

Any suggestions?

 

[Agile]

Its difficult to guess but you must have the pressure at 1.5 Bar if you want it to work.

Is the DHW working?

My best guess is that the auto air vent may not be working properly and there could be air in the system which is not being expelled. Alternating for 20 secs on CH and then DHW might help to clear it.

Tony

 

[ChrisR]

If you drop the front panel of the boiler you'll see the pump on the right. Just behind it is a 50mm round air vent device with what looks like a car tyre valve on top. It's important that that cap is left permanently loose so air can get out. You can remove the cap safely, it might be blocked with scale. Often they leak a tiny bit.

 

[kenbo9]

Thanks Tony - will try that when I get home.

Chris, again will have a look later but if the vent was blocked would the hot water work?

Can I rule out a burst pipe?

 

[kenbo9]

I have a Valiant Turbomax Combi Boiler which has worked well until my latest attempt at decorating which involved taking and putting back on a radiator.

Before switching the heating on I had to refill system as it was at zero. As instructed I did this to just below 1.5 bar. Incredibly radiator (and others) heated up but I noticed that the pressure quickly fell to zero. I refilled, switched on and radiators again warmed up but CH switched off after a couple of minutes. It has continued to do this. Hot water supply is working perfectly. Pressure appears to have stabilised.

Any suggestions?

Got home and pressure down to 0.5. Refilled but ch not firing up at all or making any attempt to do so. Hot water still ok. Any suggestions?

 

[gasgeezer]

Did you drain out of the p.r.v if you did look outside and see if the pipe is dripping could be the p.r.v letting-bye

 

[kenbo9]

Thanks Gasgeezer - looked ouside but difficult to tell as raining! But don't think so.

Funny thing is I tried switching CH on again and it fired. Pressure dropped from 1.5 to about 1.3 and then slowly climbed to about 1.9 and I decided to switch off after about 3 mins. 10 minutes later pressure down to 1.6 so put CH on again, and watched as pressure slowly climbed again. At 1.8 it cut off but immediately fired up again. Pressure continued to rise and I switched off again at about 1.9. Seems unusual but then again what do I know!

 

[ChrisR]

Hmmm.. Didn't turn off the isolating valves under the boiler did you?

 

[kenbo9]

Other than the normal everyday on/off switches the only control I've touched has been the 1/4 turn lever to refill?

I'll keep a note of what happens over a period in case that throws up something. Thanks for your comments.