Boiler and Pump continue running when no demand

[Scorpion101]

Hi all.

I recently had a new boiler (glowworm energy 30c) fitted along with a nest thermostat.

Everything seemed to work fine. I had a small incident early on whereby the CH stopped working. After a bit of investigation it turned out to be the motor had stopped working within the actuator on the zone valve. I got a replacement actuator and all was good.

Now I find that the boiler and pump seem to intermittently carry on running when there is no demand for heat from the thermostat. After an inspection I've concluded that the microswitch might be failing in the new actuator I fitted and it is stuck on. It doesn't happen all the time. It could also be the microswitch on the water actuator. One of the two.

Does this sound like a likely cause? But if the zone valves are closed where is the water being pumped to?

 

[CBW]

Did you replace the actuator? If so double check your wiring 1. Hasn’t created a short circuit, and 2. Isn’t crimping the insulation.

 

[ianmcd]

sounds like your installer has left the link in 24V RT this has to be removed

 

[Scorpion101]

Did you replace the actuator? If so double check your wiring 1. Hasn’t created a short circuit, and 2. Isn’t crimping the insulation.

Yes I did. I've just reviewed the wiring. All looks good however I've just removed the actuator and all works as expected with it removed. So I may have crimped a wire when fitting. Strange how it has only surfaced now though.

However I'm now having a problem with the mechanism. The cog and wheel are now jumping. Serves me right for buying a cheap replacement.

I'm going to go and get another to try and see if that solves my problem.

 

[Scorpion101]

Ok so I've replaced the actuator ....and... I still had the problem.

Looks like it wasn't that one causing the heating to remain on. Although it did need replacing due to the mechanism.

I tried the other hot water actuator and it appears that there is a current coming continualy down the orange wire so I'm assuming this is a call for heat.

I'm going to order another one and hopefully this will correct my issue.

I've since reviewed the wiring and all yet again seems to be correct.

 

[ianmcd]

Ok so I've replaced the actuator ....and... I still had the problem.

Looks like it wasn't that one causing the heating to remain on. Although it did need replacing due to the mechanism.

I tried the other hot water actuator and it appears that there is a current coming continualy down the orange wire so I'm assuming this is a call for heat.

I'm going to order another one and hopefully this will correct my issue.

I've since reviewed the wiring and all yet again seems to be correct.

Yes the wiring will be correct, it will be the end switch or micro switch in the valve actuator that has jammed

 

[Scorpion101]

Yes the wiring will be correct, it will be the end switch or micro switch in the valve actuator that has jammed

I've just removed the actuator. Stripped it down had a poke about and put it all back together. Once fitted it was working correctly again. I'll have to keep an eye on it but so far so good. Hopefully save me some money in buying another one for now.

The other CH valve appears to be a bit stiff. It turns but the turning doesn't seem to match the actuators turning motion. The manual override is somewhat loose so the valve is open a bit when it should be closed. I think the valve itself will need replacing in the future but that is something for another thread.

 

[Scorpion101]

I've not had any major issues during the last 24 hours. All seemed to be working correctly. During the
day the water worked correctly and the thermostat on the tank would cut it off correctly when it was at the correct temperature during the times that the hot water was set to be on. However, in the last hour I discovered that the tank had passed the heat of the thermostat but not shut off. The orange wire was still sending a current despite this.

The actuator seems to work correctly during the times set but for some reason the thermostat seems to be temperamental even though at the time I could here it click at the temperature of the water, which had reached approx 70 despite the thermostat being set to 60.

I've again checked the wiring and had a retest and now it seems to work correctly again but there does seem to be some gremlins in the system which for the life of me I'm struggling to get to the bottom of.

 

[Scorpion101]

Came home today to find the hot water still heating despite when turned off or the thermostat kicking in. I gave in and made a trip to screwfix. I replaced the other actuator for hot water. Now all appears to work correctly now. Fingers crossed it stays like that.

Wish I'd opted for a combi!