Potterton EP2001 replacement with EP2

29 Jan 2014
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United Kingdom
I have just tried to replace my old Potterton EP2001 Central Heating and Hot Water timer with an EP2. As you know it is a very easy exercise (even for me!) as the back plates are identical.

However, the central heating won't come on (HW works though). I have tried various configurations of the Programmer, particularly 7 (Fully Pumped) which the Installer Guide says is the programme for the EP2002.

Worryingly, there is no mention of an EP2001 in the guide but I read that the EP2002 was the replacement for the EP2001.

I know that there is nothing wrong with the CH valves or pump as I have hot wired the back plate connectors 4 and 5 together and am enjoying the CH (have also switched on the immersion in the hot water tank).

Can anyone help?
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Thanks but tried that. The CH & HW share the same pump but the valves for CH still don't open.
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Check the pins on back of programmer or replace existing back plate for new one.
what was the reason for replacing the programmer in the first place, Did you have an existing fault or did you just want an updated one ?
Thank you all for you replies. Answers to each are as follow:

I don't know whether Y or S. How do I tell?

I have put in the new back plate and am certain that I have got the wiring correct; the hot wiring of 4 & 5 is on the new plate.

The reason for the replacement is slightly embarrassing! The clock was losing 6 hours over-night and I guessed that the battery was giving up the ghost after 20 years. I didn't know how to remove the control and damaged the printed circuit board in the process. When I refitted it, I got no light at all. Hence reaching for a new one.
Y or S is easy, you will have L and N, 3 wires into backplate is Y, 2 is S. Or you could check airing cupboard. You could've put CH wire in too far and tightened the sleeving and not the core.
Mine is S. I have L and N and two wires. I have reset the CH wire (and live link to 5) - no difference and indeed my hot wiring of 4 and 5 has always worked.

On the subject of poor connections though, I notice a crackling sound in the programmer when I switch on the CH (but not the HW which has always worked fine). I wonder if I have a faulty box?
After replacing two EP2002s that developed faults within a couple of weeks I swapped to a different make. Means changing the back plate but no problems since.
Picked up a new EP2 at Plumb Centre and instant success! I asked them whether they had had problems with the EP2 to which they replied No but that it was too new to tell.

As an amateur, it is usually the case that 'non functioning' is as a result of my school boy error, rather than a brand new bit of kit being defective. You experts would have known that you had done everything correctly and would have spotted the signs.

The comments/questions from all who contributed were most helpful in giving me the confidence that it was NOT me this time.

Many thanks indeed.


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