Author Topic: Central heating thermostats  (Read 382 times)

Central heating thermostats
« on: May 17, 2019, 02:24:56 pm »
Hoping someone on here can stop me going bonkers. I’ve got a wireless thermostat controlling my boiler and periodically it develops a mind of its own. Although the thermostat doesn’t call for heat, the boiler fires anyway and runs the central heating, sometimes for hours at a time. The house is actually uncomfortably warm at this time of year and no amount of manual overrides stops the boiler from firing, then just as suddenly the boiler will stop. Under the boiler itself there is a control box with 2 lights. As I understand it, the red light indicates a link to the thermostat and the green light comes on telling the boiler to fire, even though the thermostat is not indicating demand for heat?

It’s driving me nuts, any ideas?

Regards

A

Kim

  • Timelord
Re: Central heating thermostats
« Reply #1 on: May 17, 2019, 02:37:23 pm »
If it's like the one we've got, you can pull the front cover off the little box with two lights and slide the switch hidden underneath to 'off', disabling the receiver unit and keeping the heating off until you switch it back on again.

I've had it phantomly run the boiler a couple of times, but mostly keep it off in favour of my own superior control system wired in parallel.  I leave it connected with the thermostat set low as a fail-safe in winter.

You could try fresh batteries in the thermostat, but it seems like a lack of robustness in the wireless communication protocol used.  I think there are some DIP switches or something to set an ID number - it might be worth changing on the off-chance a neighbour has a similar device causing a clash.
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caerau

  • SR x 3 - PBP fail but 1090 km - hey - not too bad
Re: Central heating thermostats
« Reply #2 on: May 17, 2019, 02:46:53 pm »
We had problems with our newly installed Hive system for a couple of years, boiler being on when it shouldn't, taking hours to fire up when asked to etc...


Turned out there was something wrong with the boiler itself (a borked valve of some king) - I'd been blaming our wifi network for being shite the whole time.


Worth getting an engineer in I'd say.  It was our annual service that finally spotted the real problem.
It's a reverse Elvis thing.

Kim

  • Timelord
Re: Central heating thermostats
« Reply #3 on: May 17, 2019, 02:51:32 pm »
If that were the case, I'd expect boiler activity not to track the "demand for heat" blinkenlight on the receiver.  Easy enough to work out where the problem lies.

(AIUI the red light is simply a "power is on" indicator, it doesn't actually maintain communication with the thermostat at all times - which would greatly increase the power requirements of the battery-powered thermostat - it just reacts to "heating on" and "heating off" packets when it receives them.)
To ride the Windcheetah, first, you must embrace the cantilever...

caerau

  • SR x 3 - PBP fail but 1090 km - hey - not too bad
Re: Central heating thermostats
« Reply #4 on: May 17, 2019, 02:56:27 pm »
Maybe, it befuddled us for a loooong time.


Certainly I'd try your suggestions first, more economic to do so.
It's a reverse Elvis thing.

Basil

  • Um....err......oh bugger!
  • Help me!
Re: Central heating thermostats
« Reply #5 on: May 17, 2019, 02:58:17 pm »
Our Honeywell controller by the boiler has a red light and a green light.
The green light shows that it has good radio communication with the thermostat in the hallway.  The red light indicates failure of some sort.

Yours may not be the same.

Is your thermostat battery powered?  If so, start by replacing them.  You may then need to go through the "Teach-in" procedure.
Quote from: Kim
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