central heating permanently on, faulty motor?

[vincechiew]

My central heating won't turn off via the wireless thermostat. I can see that it communicates correctly so suspected a problem with the zone valve. It is a Honeywell 2 port and I notice the manual level is completely loose and I can't lock it in the manual 'on' mode. We have other zones and those valves are stiff when off but can be manually moved to 'on'. I thought it might be an problem with the motor so I have replaced the synchron motor but it did not resolve the issue. Does this mean that the zone valve is faulty and needs replacing and if so is this best left to a professional (as you have probably guessed I am a complete amateur).

Attached a photo of the valve and also the motor I took out which around the cog had a brown thick stain on it which was suspicious. Any ideas?
Not a massive problem at the moment as can turn the rads off but would like to fix it.

 

[SimonG]

That's the hot water motorised valve. Or is the picture just for effect?

 

[SJB060685]

Do you have a multimeter? If so some simple checks will show you where the feed is coming from.
Most likely valve body seized in open position keeping end switch contacting, could take head off valve and see if spindle is free.

 

[Harvest Fields]

By the look of the motor it needs a new complete valve. Is it a sealed system?

 

[king of pipes]

Replace the whole power head or if possible the whole valve the linkage wears on them and fails to activate the micro switch when eithier calling for heat or when its satisfied so just stays on . Kop

 

[vincechiew]

That's the hot water motorised valve. Or is the picture just for effect?

That was just to show the brown stain on the cog, not sure how it got there but quite gooey.
[automerge]1591954664[/automerge]

Do you have a multimeter? If so some simple checks will show you where the feed is coming from.
Most likely valve body seized in open position keeping end switch contacting, could take head off valve and see if spindle is free.

Thanks, is the spindle the lever thing sticking out? When I have removed the motor it seemed to shut the valve but once I put the new motor in when I tested it and it opened it wouldn't shut again. Do I need to drain the system in order to take the head off?
[automerge]1591954716[/automerge]

By the look of the motor it needs a new complete valve. Is it a sealed system?

It is a sealed system, guessing that is not a DIY job to replace the valve?
[automerge]1591954768[/automerge]

Replace the whole power head or if possible the whole valve the linkage wears on them and fails to activate the micro switch when eithier calling for heat or when its satisfied so just stays on . Kop

Thanks, sounds like it does need a replacement then.
[automerge]1591955094[/automerge]
Appreciate the advice - sounds like a new valve/power head. I see that Honeywell part is around £50, do you know what's the ballpark for a plumber to fit it. It's a four bed semi, sealed system. Thanks again!

 

[SJB060685]

Thanks, is the spindle the lever thing sticking out? When I have removed the motor it seemed to shut the valve but once I put the new motor in when I tested it and it opened it wouldn't shut again. Do I need to drain the system in order to take the head off?

The "lever thing" you mention is the manual open and fill lever. The spindle is the shaft from motor to the valve assembly inside and can be accessed by undoing a couple screws in the actuator head and removing it from the top.
You don't need to drain down to take the head off and access the spindle, although i recently had one where the spindle snapped taking the head off which as you can imagine released water from the system, so be careful if you decide to try.
If you decide to replace the whole valve then yes you will need to drain down. Electrically its easy enough but thats probably best left to someone who's familiar with it.

 

[Harvest Fields]

Sealed, means it is a lot easy, ( if you are hands on capable with electrics and a fair diy’er).

 

[king of pipes]

£150 - £175 for a new valve and fitting depending on your area .

 

[Aquarius]

It looks like an unvented cylinder to me, so be careful as you may need a G3 registered plumber/engineer to replace.

 

[Harvest Fields]

It looks like an unvented cylinder to me, so be careful as you may need a G3 registered plumber/engineer to replace.

Not for the valves. But if you are not confident then definitely get a pro in.

 

[Aquarius]

Not for the valves. But if you are not confident then definitely get a pro in.

Thanks. It's cloudy to me as someone on another forum said some of the valves are a safety feature?

 

[Harvest Fields]

Thanks. It's cloudy to me as someone on another forum said some of the valves are a safety feature?

The ones that attach to the cylinder itself, are safety valves and yes you need to be G3, but the motorised valves are part of the boiler circuit and no G3 is needed.

 

[vincechiew]

Is the 3G a plumbing qualification? Should they be part of a register when I hire one in? Sorry for all the questions.