Central Heating cannot be turned off! Potterton EP2002 timer

craig51 said:

If it is solid, and you can free it up, i would put money on it going solid again after a few weeks and lots of hot/cold cycles. Just some friendly heads up advice for you. I've been there before only to have to go back and change it.

Its not too hard to change. You can bung it , but if your a novice the simplest way is

1/ Isolate either the feed into the header tank, OR the mains into the house.

2/ Open drain point outside. This will start to drain the system top - bottom. If the 3 port valve is in the upstairs cupboard, you only really need to drain the header tank and the pipes leading down to it. To prove the water is down to that level, once drain is open, wait 2mins, then open a bleed point on a radiator. If no water comes out, close the drain, and slowly but surely undo the 3 couplings.

3. Once replaced, while not forgetting to fit in the right direction, turn on water and bled rads etc.

4. turn power on and hope for the best.

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Hi to all

Thanks so much for helpful replies received on this thread. It turned out that that 3-way diverter valve was the part at fault, and I initially removed the silver motor unit from it, to pop the new one on (done completely blind, as you can see in the pic it can't be twisted to be make it more accessible!) - I can't tell you what a pain in the a**e it was to take the old silver head off and pop the new on!

However, mid-job, I was twisting the brass knob that moves the valve itself and it was initially too stiff to turn by hand (obviously the cause of burning out the motor unit and rendering the whole valve inoperable). At this point, I didn't know how to drain the system as had been suggested above, but I couldn't leave the system as it was, as the weather was starting to turn cold! I spent some time working the valve knob with some pliers to help free it up as a short-term measure, and popped the new silver motor back on - it worked fine.

However, I wasn't at all happy with leaving it like this, and figured that it was only going to be a matter of time before it bunged up again and wore out the new motor. I asked a family friend (plumber) if they'd assist me by showing me how to drain the system so that I could fit the new brass valve. By this family friend, I was quoted £280 (!!!!!) for the work as it would "take half a day". I politely declined and vow never to use a plumber again. (I didn't expect him to do it for free - but 280 notes?!)

I spoke to a friend of mine who is a landlord and maintains his own properties and he talked me through the solution. It sounded like an awful job and I didn't fully get it, so persuaded him to pop round and show me.

Now that I know how to drain the system (as simple as opening a bleed valve on one of the rads downstairs into a hosepipe that was attached to it to take the water outside the house), and then being to unbolt the old valve, bolt in the new one etc and turn back on the water supply to the header tank - it was actually pretty straightforward. It would be really useful if someone did a photo / step by step guide for anyone else that would like to be able to do jobs like this, but just don't have the confidence (having never done it), to tackle their central heating system. I wished I'd taken pics as I was doing it now, otherwise I'd have done it myself.

The job actually took about 90-100 minutes, doing it slowly and carefully and taking our time. Now that I know what to do, I reckon it could be done again by me in about an hour.

I do not know where this plumber got half a day from. The bulk of the time being quoted as "draining the system" - this took us about 15-20 mins to get sufficient water out of the system to take the water level to below where the valve is. I simply cannot believe it could take half a day to this job.

So in summary, am 280 notes better off, with a good deal of satisfaction of having done the job myself and being able to tackle stuff like this again much more confidently in the future. My thanks for the contributions above from all of the helpful posters. Problem diagnosed and solved!

Glad you got it sorted. It's quite satisfying to work through the problem and fix things, gets quite additive - especially with the wealth of info online

tryitandsee said:

Glad you got it sorted. It's quite satisfying to work through the problem and fix things, gets quite additive - especially with the wealth of info online

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Indeed - BTW, I tried to PM you about the spare Potterton timer that I now have. It wouldn't let me until we were "friends"! Drop me a note back if you are still interested.....

Thanks, that's very kind. Yes still interested, as the sliders have given up the ghost on mine. Although the programmer works perfectly if not fiddled with

Not sure how to give you email address or whatever needed!!!

tryitandsee said:

Thanks, that's very kind. Yes still interested, as the sliders have given up the ghost on mine. Although the programmer works perfectly if not fiddled with

Not sure how to give you email address or whatever needed!!!

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If you accept the friend request, you can send me a PM.... Can't put my email address in an open thread!