CH not staying warm

[sjgill]

Hi there.
I'm getting real problems with my CH since the pipes were drained for replacing bathroom taps last weekend. The system is not very old (House is only 8 years old). The CH gets warm when the timer switches it on but when it reaches that temp then the radiators start to cool but never get hot enough again for that cycle even though the temp of the house is definately not what the thermostat is set at. I've tried bleeding the radiators starting downstairs then going upstairs and I've also bled the pump but it seems to make no difference. The pump seems to be working fine and there is plenty of HW.

Any suggestions?

Thanks

Stuart

 

[Plumber Will]

Can you hear the pump running..it may be sticking (give it a whack with a hammer)....when in doubt give it a clout.

 

[sjgill]

Clout, kick, hammer.... no need as the pump appears to be working. I've tested the pump on different speeds as well and you can notice the difference so it appears fine.

 

[Plumber Will]

Do you have thermostatic rad valves? or a room thermostat?

 

[sjgill]

We have controls on the radiators (they are on full at the moment) and an overall thermostat in the hallway which is currently set to 22. The radiators heat up to the expected level when the heating first comes on but after it reaches the temp then they never get very warm again. They tend to stay slightly warm but not enough to make a difference in temperature.

 

[Plumber Will]

Sound like the room stat is at fault!

 

[sjgill]

Sucess! I got home and checked the pump and made sure everything was ok with the radiators and then switched the heat on. Sure enough it heated up and then cooled down very quickly. I looked at the boiler and it's a potterton f40. There was a small circular hole on the bottom of the boiler which I touched and the whole boiler sprung to life and is now keeping the entire house at a comfortable temp. Not meaning to sound like a complete novice but I don't know what was in that hole but glad I found it! I've looked for the manual for this boiler online but I can't seem to find it. Just wait and see over the next couple of days to see how it continues.

 

[sjgill]

Not so much sucess. The heat came on this morning but it went off again after about 40 minutes instead of 15. It appears there is a valve under the boiler in that hole that I touched that could be at fault. I noticed potterton do not have the manual for the model boiler I have. It's only when i shut the valve that the boiler really comes to life otherwise there is just a small flame in there.

Any ideas? I'll contact potterton direct today for a manual if they have it.

Update: The boiler behaved the same way tonight but when I turned it up then it fired back into life. I've set the boiler to max to see if it is locking out through overheating trying to heat the house. Any more suggestions if it's not this before I have to call someone in?

Thanks

Stuart

 

[sjgill]

OK, Latest is I've bled all the valves and still nothing. I did however find the lever to adjust the Mid-position valve to be broken off by the previous owners of the house. There was also a grinding noise from it so I've given in and called an expert.

Thanks for all your help.

Stuart

 

[sjgill]

OK, Engineer came out and the thermostat on the boiler has gone. Will replace next week when part in stock.

Thanks for the help

Stuart