Central Heating cannot be turned off! Potterton EP2002 timer

[rjsdavis]

If you are going to replace the Potterton EP2002 controller and you haven't yet done so, my advice would be to replace it with the EP6002. The back plate is the same on both so its a simple swap if the old one isn't faulty. I speak from experience.

The EP6002 provides three timed periods per day and allows the CH to be switched on/off separate to the hot water.

Having said all that, if you are going to replace the old stat with a modern, programmeable one, then you will probably leave the CH set to be on all the time on the controller (with the stat now controlling the on/off times). If that is the case the EP6002 doesn't really offer any benefits over the EP2002.

Thanks Felix - I haven't yet managed to source the replacement just yet.

In actual fact, we have the HW and CH coming on twice a day, and the programmer has always say on TIMED, with the EXT button being used if it was particularly cold and we needed it to come on earlier or for longer. I'm anticipating getting a brand new from Ebay and simply ulling the old unit off, and pushing the new one on - as the backplates are the same?

However, you've now raised a query - insofar that could the backplate actually be the source of the problem? I.e. with the CH & HW coming on at the programmed times, irrespective of the positions of the slider controls - we're now trying to switch OFF the the CH as it's so warm, but it keeps coming on regardless of the slider being set to OFF, and the thermostat in the hall being turned down to 0!

 

[rjsdavis]

You read the numbers from it and posted them above, and you still want to know where and what it is?

Sorry gasman, but none of your replies make any sense like everybody elses..... I'd like to reply, but it appears to be critical when I've asked a perfectly reasonable question. Thanks anyway.

 

[rjsdavis]

It is the most likely cause, but it COULD be a sticking diverter valve.

Right. New EP2002 installed, waited for the programmed to come on for the central heating - unbelievably - it still came on at the programmed time!

I'm stuck now - as I was so sure that it had to be the programmer being at fault.

I don't understand why the central heating will only come on at the programmed times, and effectively over-ride the programmer - how can a mechanical device (like a diverter valve) can override the switching and control circuitry of the Potterton EP2002??

If it is a sticking diverter valve, how do I determine whether it is or isn't - and how do I replace it?

Thanks again in advance for any help....

 

[rjsdavis]

If you are going to replace the Potterton EP2002 controller and you haven't yet done so, my advice would be to replace it with the EP6002. The back plate is the same on both so its a simple swap if the old one isn't faulty. I speak from experience.

The EP6002 provides three timed periods per day and allows the CH to be switched on/off separate to the hot water.

Having said all that, if you are going to replace the old stat with a modern, programmeable one, then you will probably leave the CH set to be on all the time on the controller (with the stat now controlling the on/off times). If that is the case the EP6002 doesn't really offer any benefits over the EP2002.

Thanks for this reply Felix...

I'm still getting my head round the financial benefit of having the central heating on permanently and being controlled by the new stat, as opposed to it coming on only first thing in the morning, and in the evenings on most days which must surely be using less gas to heat the house than having it on all day and running 24 hours?

That's the plan at least.

In any case, the new programmer hasn't actually cured the central heating coming on problem, and need to work out what other part is still causing this issue... Hopefully I won't need to resort to a heating engineer to come out and stiff me with a big bill for the diagnosis!!

 

[rjsdavis]

Sadly, this was wired in and appears to be working perfectly, but has made bubkiss all difference!

Grrrr.

Ok, so it appears to be a sticking diverter valve? What is this, and can I fix this myself? Or is on one of the water pipes and I really need a plumber to sort it out?

Thanks in advance for any assistance....

 

[rjsdavis]

Also - will be installing this much better looking thermostat whilst sorting this mess out.

I've pulled off the thermostat cover of the old one, and have posted up a pic below:

Old Thermostat

• rjsdavis
• 26 Jun 2012
• 1

This is exactly as was wired with just the cover removed. Blue wire not connected to anything.

As you can see, the yellow and red wires are the only ones wired in, along with the yellow/green earth.

This is how I think I should use the same wires in the new backplate of the new Siemens thermostat - is this correct?

New Siemens Thermostat backplate

• rjsdavis
• 26 Jun 2012
• 1

This is how I am guessing I should wire it in based on where the old wires were connected to the...

Key questions are:

1 - is the wiring correct?
2 - should I just leave the yellow/green earth wire unconnected along with the blue one?

Thanks very much for any replies....

 

[tryitandsee]

Perhaps no help to you, but I have a EP2002 programmer that have both sliders broken. I took the programmer apart and the basic engineering of these sliders is appalling. Two very small copper connections on the slider touching copper plates on the PCB. (It works a bit like a scalextric car on the track)

The slider would not turn off the central heating when slid to off. One of the two copper connections on the slider was not making contact with the PCB.
However you have replaced with a new programmer so rules that out.

Perhaps the motorised valve as others are pointing to has stuck giving both hot water and central heating. New syncron motor needed perhaps in the motorised valve.

If you need a good home for you spare programmer, would be more than happy to take it off your hands as mine is still functioning, but not as I would wish it too.....

 

[rjsdavis]

However you have replaced with a new programmer so rules that out.

Perhaps the motorised valve as others are pointing to has stuck giving both hot water and central heating. New syncron motor needed perhaps in the motorised valve.

If you need a good home for you spare programmer, would be more than happy to take it off your hands as mine is still functioning, but not as I would wish it too.....

Thanks for the reply. When I've got it fixed and sorted, happy to let the old EP2002 go... Will let you know as and when.

As for the sticking motorised valve - what is this, and where can I find it? Is it something I can unbolt myself and pop a new on? Or is this a job for a plumber/electrician/heating engineer?

Many thanks

 

[tryitandsee]

www.youtube.com/watch?v=Yyn_fBEH90U

Try watching this, if not your problem, at least more interesting than the tennis

 

[rjsdavis]

www.youtube.com/watch?v=Yyn_fBEH90U

Try watching this, if not your problem, at least more interesting than the tennis

Thanks alot - that's a really helpful video and I know exactly what part you're talking about now....

My question is: (and having watched that video it doesn't answer it): Where I seem to have an issue with the central heating/hot water coming on at the programmer times irrespective of the on/off/timed buttons, do I basically need to replace the whole silver box part of the motorised valve?

I've had a fiddle with the switch on the bottom, and there is no resistance on it all, and certainly doesn't slowly cruise back into place when you release it.

I'm guessing that the motor part itself is kaput - and therefore the syncron motor needs to be replaced? Does that make sense? Or am I missing something...?

I'm happy to simply buy a new box and pop it on, as given it's age, it makes economic sense in the long run to just buy a new one - however, if possible, I'd like to fix this myself and wire it in, but am not up to draining the system - I'll only attack it, if I can remove the motor / silver box housing as it shown in the video which didn't require any issues at all with the water supply.

 

[45yearsagasman]

May 15th til now and you still haven't fixed it.

 

[tryitandsee]

Getting to my limits of usefulness I'm afraid

It sounds to me that the valve has got stuck with the micro switches in the on position. Not sure how that works when you say both sliders on the timer are switched to the off position!!!

Not sure if there is any way to free the gears/working of the valve. What ever way of doing that you would have to be careful of live electrics etc.

Perhaps that would become apparent when/if you take it off. Freeing the valve may resolve the function of the three way valve, solving the problem!

However requesting a plumber to call with the hope of now sounding a bit more confident regarding three way valves is somewhere near to saving you a bit of money.

 

[matt1e]

I'm still getting my head round the financial benefit of having the central heating on permanently

Hi rj
firstly, I'm confused, in your earlier posts you said that the fault was that the hotwater and the central heating were both following the set times in the progammer (as in switching on and off),even when the programmer's sliders were turned off

That's a fault in the programmer ..........end off, nothing to do with the valve

now you are saying that the heating is permanently "on"

That's a programmer or wiring fault ........ end off, nothing to do with the valve

you need to be a bit more clearer on the fault symptoms mate

secondly don't take the video link too seriously as it's inaccurate in parts, (3m22s) although the valve does indeed switch on the boiler in central heating mode it has nothing whatsoever to do with switching on the boiler in hotwater demand also the orange sources power from the white, not the grey as stated in the video

do I basically need to replace the whole silver box part of the motorised valve?

I've had a fiddle with the switch on the bottom, and there is no resistance on it all, and certainly doesn't slowly cruise back into place when you release it.

I'm guessing that the motor part itself is kaput

if the heating is as you say permanently on then that is normal and what you would expect, stop guessing mate it will cost you money.

right, reboot
turn off all power to the heating system, check the valve now, has the lever got resistance?
what happens if you lift the programmer off the backplate and switch on?
nothing?
Matt

 

[rjsdavis]

May 15th til now and you still haven't fixed it.

I might have done if you'd posted a helpful reply like everyone else. Please don't post anything else, as I can do without the sarcasm from forum trolls.

 

[rjsdavis]

firstly, I'm confused, in your earlier posts you said that the fault was that the hotwater and the central heating were both following the set times in the progammer (as in switching on and off),even when the programmer's sliders were turned off
That's a fault in the programmer ..........end off, nothing to do with the valve

Thanks for replying matt1e - you might have missed it in my earlier post, but I've now fitted a brand new EP2002 programmer - this made zero difference to the problem as my logic was the same as yours.

now you are saying that the heating is permanently "on"

Nope - I'm saying the same thing - which is:

The heating AND hot water come on, at the EP2002 programmed times, irrespective of the position of the controller switches of the programmer - it doesn't matter if they are on TIMED/OFF/ON etc - it always comes on at the same times.

This is fine for the hot water, as we want this to come on at these programmed times, however, we don't want the central heating coming on at all in this hot weather!

do I basically need to replace the whole silver box part of the motorised valve?

I've had a fiddle with the switch on the bottom, and there is no resistance on it all, and certainly doesn't slowly cruise back into place when you release it.

I'm guessing that the motor part itself is kaput

if the heating is as you say permanently on (NOT CORRECT) then that is normal and what you would expect, stop guessing mate it will cost you money.

Nope - not permanently on. Just coming on when the programmer hits its on and off times. It follows the programmer religiously even though the programmer switch is OFF (for central heating)

right, reboot
turn off all power to the heating system, check the valve now, has the lever got resistance?
Matt

Made no difference. No resistance in the valve switch at all - it will happily stay at either end, whichever position I put it in (or even halfway if I leave it there).

what happens if you lift the programmer off the backplate and switch on? [\quote]

Yes, nothing. I'm presuming that this is because the circuit to switch on the hot water/central heating cannot possibly complete with the programmer removed?