No hot water again

aylesby

My Potterton condensing boiler does not always connect with the Grasslin timer commands. We cannot demonstrate the problem to our service engineer because it usually affects heating water in the morning.
When it fails to start the boiler will not come on under any command and yet when the service engineer arrives it immediately starts under a constant command.
Any advice if it’s the timer or the boiler and is this an electricians or a central heating service problem. If you know of anyone who covers Knutsford please let me know as I have to fix this before winter comes.

Owain_Moneysaver

I assume this is not a combi system but that you have a hot water cylinder.

It's possibly a sticky microswitch in the valve which will look something like this, and probably be somewhere near your pump



Two or three pipes to it, and an electric cable.

What is supposed to happen is the timeswitch sends electricity to the valve, which then operates and the actuator opens the water pipe. The actuator also operates the microswitch, which then sends a 'call for heat' signal to the boiler.

The electrical motor/switch head on these valves is usually replaceable separately from the valve body, without removing any pipework or turning off the water.

There's also usually a manual lever on them you can operate manually, giving that a wiggle may resolve the problem or at least provide a temporary work-around.

ormus

which actual potterton model/type/number is the boiler?

aylesby

Thank you for the responses
We toggle the micro switch which is heavy over half its passage and then it ticks back. After half a dozen toggles it is sharp on the fingers co I give up. Its advice we have followed but nothing seems to happen.
The daft thing is in a couple of hour’s time the control wills be working normally.
It’s a Potterton 24HE Promax and LWP0345 might mean something. Memory says the boiler is 8 years old. The controller is a Grasslin Towerchron QE2 being 3 years old.

macman

Suspect it's temp -related, as it sticks when cold and is OK when warm?

ormus

http://www.potterton.co.uk/docs/Potterton_Promax_Combi_HE_A_User_guide.pdf

have you tried the troubleshooting section in the user guide?

Canucklehead

Hi,

OP.

Are you saying that when the programmer is on 'TMD' it does not fire the boiler, but when switched to 'CONST' it will fire?

GSR.

aylesby

The boiler is set to come on every morning and thats when it might fail and it will not come on even if timed is moved to constant. Wait a couple of hours and every thing is fine and it will fire up on constant.
This problem occurs two /three mornings each week.

Canucklehead

Hi,

It needs testing electrically, to find where in the chain it fails.

Most GSRs should be able to find that out.

GSR.