Odd problem with heating/boiler. One-off or something on the way out?

Mottie said:

I think I’ll wait until the summer when the heating is not used, drain the system down and just replace both valves complete with heads etc.

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honeywell valves ? take the metal cover off and have a look as it motors over there is a little brass paddle that you will see moving and it then activates the micro switch you can twist it a little bit to get it to touch microswitch if its just not quite making it .

As for both what has prob has happened is HW one went first so valve will have been opening and because you have been using the heating for months now the cylinder will heat up . Now the heating one is playing up it is showing both being faulty

A confession. I've been lazy. I’ve done feck all about it but THIS time I’m going to sort it. Definitely. One more clue. Set the heating to come on this morning at 5.30 for the first time this year. I can tell that it’s come on as I hear the rads/pipes ticking. Of course, this morning it didn't. I checked it, saw that the pump was not on, felt the motorised valve and while the pipes were cold, the valve cover was pretty warm. Turned central heating spur off, then back on and everything started working. Thing is, every month or so during the summer, I’ve whacked the heating on for 10 minutes or so to make sure things are working okay and they have been but come the first cold morning, it’s started playing up again. The hot water is permanently on and that’s never played up.

Is it likely to be the electrical head or shall I just change the whole bloody thing? I would like to try to avoid draining the whole system down if possible. If I take the head off, should I be able to see whether the actual valve is stiff by trying to turn it by hand?

Well, I’ve fixed it - or at least I think I have! Took the electrical valve head off and found that the spindle on the zone valve could be moved easily by finger pressure so not seized or stiff/sticky. Didn’t move much though so I also took the head off the hot water zone valve and compared movement - both were the same so I assumed valve body was okay. Bought a new powerhead and fitted that. That came with one extra (white) wire in the cable but instructions said to not use that and isolate if using the new powerhead to replace the one I had, which I did. Powered system up, pump ran for about 5 mins before stopping. Turned the thermostat up and after an agonising wait of 15 seconds, the pump started up and is now pumping hot water around the system. The true test though will be at 5.30 tomorrow morning!

Mottie said:

Well, I’ve fixed it - or at least I think I have! Took the electrical valve head off and found that the spindle on the zone valve could be moved easily by finger pressure so not seized or stiff/sticky. Didn’t move much though so I also took the head off the hot water zone valve and compared movement - both were the same so I assumed valve body was okay. Bought a new powerhead and fitted that. That came with one extra (white) wire in the cable but instructions said to not use that and isolate if using the new powerhead to replace the one I had, which I did. Powered system up, pump ran for about 5 mins before stopping. Turned the thermostat up and after an agonising wait of 15 seconds, the pump started up and is now pumping hot water around the system. The true test though will be at 5.30 tomorrow morning!

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isolate the white correctly as i has live on it at times . Seen them several time just left loose in wiring centre

Update……..Still working!

Definitely success. Been away for 4 days, put it in holiday mode and when I came home …….it was working!