Electrical Fault??

[Gone West]

My central heating decided to stop working last Tuesday. I thought I found the problem when blowing through the thermostat seemed to clear the problem. It packed up again and I replaced the thermostat and it was ok for a couple of days. Switching the main CH power switch off and on clears the problem for anything from a couple of hours to a couple of days. When I switch the power back on there is a clunk from, I think, the controller/programmer. Any ideas what the problem could be. I have the heating running 24/7 and the DHW on twice a day.

 

[ProDave]

Nobody can diagnose that remotely.

 

What trips?  MCB?  RCD?  RCBO? or post a picture of what trips if you don't know.

 

Next time it trips, switch the two slide switched to OFF before resetting it.  then try with just heating on for a few hours, then try just DHW for a few hours and see if you can narrow it down a bit.

 

The clunk from the controller is a relay energising and quite normal.

[Gone West]

15 minutes ago, ProDave said:

What trips?

Nothing trips, it just stops working. The only way to get it working again is to turn the CH power switch off and on again.

[ProDave]

2 minutes ago, Gone West said:

Nothing trips, it just stops working. The only way to get it working again is to turn the CH power switch off and on again.

What stops working?  CH, DHW or both?

 

Are the Hot Water and Heating lights on the programmer still on when it stops?

 

Can you get it working again by turning the heating or hot water off and back on again?

[Gone West]

1 minute ago, ProDave said:

What stops working?  CH, DHW or both?

Both.

1 minute ago, ProDave said:

Are the Hot Water and Heating lights on the programmer still on when it stops?

Yes

2 minutes ago, ProDave said:

Can you get it working again by turning the heating or hot water off and back on again?

Not by turning the CH or DHW off and on, on the programmer.

 

[ProDave]

When it has stopped working and you try turning heating and hot water on and off with the slide switches, do you hear the relays in the programmer go click?

[Gone West]

4 minutes ago, ProDave said:

When it has stopped working and you try turning heating and hot water on and off with the slide switches, do you hear the relays in the programmer go click?

No. There is only a clunk from the programmer when the main CH/DHW power switch is turned off and on again.

Edited 2 hours ago by Gone West

[ProDave]

I don't think a remote diagnosis can go much further.  do you have any electrical test gear like a multimeter?  Are you confident taking live readings?  If not you probably need an electrician.  But if you don't want to do that, one thing to try is a new programmer, but that is not guaranteed to work. they are easy to swap and in 95% of cases the new one will just fit onto the old back plate without alterations.

[Gone West]

2 minutes ago, ProDave said:

I don't think a remote diagnosis can go much further.  do you have any electrical test gear like a multimeter?  Are you confident taking live readings?  If not you probably need an electrician.  But if you don't want to do that, one thing to try is a new programmer, but that is not guaranteed to work. they are easy to swap and in 95% of cases the new one will just fit onto the old back plate without alterations.

OK, thanks for your time. I do have a multimeter and I have taken live readings before but I might just try a new programmer. It's just the wrong time of year. Have a good Christmas.

[ProDave]

That is indeed the simplest thing to try, just one tip when looking for a replacement programmer, avoid any that make mention of a "Service Interval" timer, often with SI in the part number.

 

Sometimes depending how it is wired, it can be very difficult getting a test probe onto what you want to measure to determine which bit is working or not.