Help! My central heating is out of control!

[elinchrom999]

Hi,
I'm having a problem with my central heating. The radiators are getting very hot and do not appear to be being regulated by the room thermostat.

The boiler,(an ancient one), cuts in even when the timer isn't set to come on.
Only way to switch it off is to turn the power switch next to the timer off.

Could it just be the timer unit itself,(a relatively new,2yrs old), digital Siemens one, or the Drayton room thermostat or both?

The system is a pumped microbore one,(aargh!), and there are no thermostatic controls on each radiator.

This system was working fine when I tested it in the summer but now we have snow it's decided to play silly buggers.
Does anything else control the boiler independently of the timer?

Any answers gratefully received

 

[D_Hailsham]

Where is the boiler located?
Is there a frost stat (turns the boiler on if it gets too cold so it will not freeze up)?. If you have one it will be near the boiler and set to about 5-10C.

 

[Tipper]

If you've got any motorised valves on the system it's probably a failed motorhead or the contacts within telling the pump and boiler to run.

Fit a new motorhead. It is possible to change just the motor but that is often unreliable as the mechanism/contacts could still be faulty.

 

[elinchrom999]

Thanks folks-I reckon the motor valve sounds right. This is an ancient Ideal Concord WRS so I'm pretty sure it doesn't have a frost stat fitting.
It's in the kitchen and the thermostat is in the lounge,(open plan 70's house).

I just checked in the airing cupboard where the cylinder is. There are 2 motorised valves in there, with slider tabs sticking out. Sounds like a plumber job rather than anything I'd be happy to tackle as I imagine the system needs to be drained before fitting the new valves-expensive

 

[Tipper]

Depends on the make of valve.

Most you can change the valve motorhead without draining down. Just a couple of screws and change the wires over.....make a very clear diagram of which colour wire goes where before you start!.....

An exception to this is the early Honeywell type that looks the same but the head is not removeable without water everywhere! You need a Honeywell with 'dimples' to be able to change the head only.

Make sure if you use a plumber that he is not changing the valve(s) complete when he could have just changed the head.

In the meantime just turn the power to the boiler off to stop it running when you don't want it.

 

[elinchrom999]

Thanks Tipper.
If you e-mail me at [email protected] I can send you a photo of the darned things! Plus a Christmas e-card of course!!!
Best wishes,
John.

 

[Tipper]

Better to post the photos on here and all can get involved.......more heads better than one!

 

[elinchrom999]

Okey dokey, good idea
Soz, didn't realise you could do that on here!
These are shot on my phone camera-they put the valves in THE most difficult place they could find

http://www.flickr.com/photos/45775364@N00/4206541326/

4 shots on Flickr-looks like Honeywell valves

 

[StarTech70]

Depends on the make of valve.

Most you can change the valve motorhead without draining down. Just a couple of screws and change the wires over.....make a very clear diagram of which colour wire goes where before you start!.....

An exception to this is the early Honeywell type that looks the same but the head is not removeable without water everywhere! You need a Honeywell with 'dimples' to be able to change the head only.

Make sure if you use a plumber that he is not changing the valve(s) complete when he could have just changed the head.

In the meantime just turn the power to the boiler off to stop it running when you don't want it.

He' s right, if you remove the Central Heating Honeywell cover (soundslike the faulty one) and see 4 screws that attach the head to the body you need a plumber (or some bungs), if it has 2 screws, 1 at the top the other at the bottom you can unscrew those and remove the head. Turn the the electrics off for you heat/hw/boiler etc before you cut the wires