Faulty CH timer?

Question

After setting the CH to off last night on the timer, I noticed the rads were still getting warm this morning. The CH is normally set to on constantly & the timing is controlled by a Drayton Digistat in the front room. Changing the settings on this revealed that the CH was firing up regardless of the setting on the timer when the Drayton kicked in. A few months back I did some retiling around the timer & used a steam stripper to remove the old adhesive. I had an incident where steam got into the CH timer & I thought I killed it. However leaving it to dry out seemed to fix it & it worked OK, or so I thought.

Could the steam incident have chimped the relay that controls the CH, or could there be another cause?

Timer is a Potterton EP2002, I've found one on ebay for £23 posted, just wanted to double check before I shell out.

Thanks

CD

Graham. · Accepted Answer

You go right ahead. That's what many heating engineers do, just keep fitting new parts racking up the bill. Sooner or later you will hit on the part that is faulty.

You might like to consider an alternative approach though. Buy a multimeter (you've probably got one) and TEST the thing!

ARWadsworth · Answer

It could be worth checking that the radiators are not getting warm when you call for only HW (no idea what boiler setup you have) but it is a possibility that you should not overlook.Adam

John · Answer

If you have a programmable thermostat then why do you need a timer? Setting the temp to low is as good as turning the CH off.

CD · Answer

I thought it could be that, but I was making the CH call with the HWoff on the timer.CD

CD · Answer

The timer is in use to give the HW a blast in the morning & evening. Iput in the Digistat to do different weekday & weekend timings whichthe EP2002 doesn't do.CD

CD · Answer

I'm as tight as they come & don't like to chuck away cash, hence my posting. I do have a multimeter but only ever use if for checking DC voltage or continuity, would it be just a case of doing the latter? There is a wiring diagram on the back, do I just check if there is a circuit between the live in & CH out connector? Your advice is much appreciated, I didn't consider this approach.

CD

ARWadsworth · Answer

That is not what I meant:-)  Do the radiators get warm if you call for only HW with the Potterton and the Drayton is not calling for the CH?Adam

CD · Answer

OK, HW on, boiler going, CH off, hand on radiator.....all very cold after a good 5 minutes running.

ARWadsworth · Answer

Well that seem to have eliminated that.There is also the possiblity that you reached a setback temperature on the Drayton last night. I had frost on my van this morning!Adam

Roger Mills · Answer

Are you sure that the Digistat gets its live feed from the programmer's CH On output rather than having a permanent live feed? Has turning CH off at the programmer had the desired effect in the past, or is this the first time you've tried it?

As others have said, you need a Multimeter, set to the 250v AC range, in order to measure the voltage relative to neutral at various points in the circuit, so as to work out what's going on.

Dave · Answer

Can you see volcanoes erupting as well?It is nicely warm in the frozen North West of England, this morning  :-)Dave

Faulty CH timer?

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