Central Heating Problem (hot water but no radiators)

Central Heating Problem (hot water but no radiators)

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Bathroom_Security

Original Poster:

3,342 posts

118 months

Saturday 27th November 2021
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Just replaced a thermostat. Something went bang. Reset the fuse breaker

The control pannel/timer thing seems fine next to the boiler
The hot water works fine
The thermostats (old and new) don't trigger the boiler to come on (central heating is on and thermostat is set high to trigger the boiler to come on)

I have put the motorised valve in manual to get heating and thats giving me heating

Is it the motorised valve or something else? The fact the thermostat doesn't trigger the gas boiler to come on seems suspect. May strip the wires back to make sure the connections are good. Maybe I wired it up wrong (not sure how)


Bathroom_Security

Original Poster:

3,342 posts

118 months

Sunday 28th November 2021
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scottyp123 said:
frisbee said:
With the hot water off, does the boiler come on if you manually open the heating valve? Or only if the hot water is on as well?
I see what you are getting at here but opening the valve manually isn't enough to operate the micro switch that turns on the boiler. I've always though that this is a stupid design in the valves. If either the thermostat or the programmer fail no amount of manual activation will get it going again.

  • It will occasionally click and power the boiler but as soon as the lever is hooked into the manual open position the valve switches off again.
No it doesn't unfortunately

Hate to admit it but wondering if I got the wires the wrong way round. I must have.

I've moved the thermostat next to the programmer now (cut the old thermostat wire and it doesn't work still. Have to say the thermostat wire is totally different upstairs to the one downstairs. Wonder if it's been joined by another wire somewhere under the floor.

I wonder if I've fecked the programmer but then why would the hot water work and not the heating?

Going to have to have a plumber/leccy look if I can get one

Bathroom_Security

Original Poster:

3,342 posts

118 months

Sunday 28th November 2021
quotequote all
3 core and earth.

At the thermostat downstairs its
Black cut back
Red and blue plus earth

Upstairs at the wiring centre what I assume is the thermostat cable is brown and blue plus earth. No black.
I can trace the feeds from the programmer so I think that's the right one.

Must be the programmer. Not a cheap fix and don't even know if that is the fix

Motorised valve is fine (it moves when the hot water comes on)

Not going to try bypassing the stat. I'll just get an electrician as I could easily blow another programmer up if thats what I've done

Bathroom_Security

Original Poster:

3,342 posts

118 months

Monday 29th November 2021
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You were right. Blew the programmer which means ive got the live mixed up. Whoops.