Two Thermostat Boiler

[nj69charlie]

I might be really stupid here but could somebody help me out with my heating system.

I live in a new build and my heating is controlled by a thermostat on the ground floor and a different thermostat on the first floor.

I have the heating currently set on a constant temp. Upstairs is set at 21 and downstairs set at 18.

Currently the heating won't come on until the thermostat upstairs kicks in. So if the front door is open and cools downstairs the heating won't kick in until the thermostat in the bedroom falls below 21.

Am I wrong in thinking that the two thermostats work independently to each other. When the bottom thermostat goes below 18 the heating icon comes on, indicating that the heating should be on but no heat.

Maybe I'm just expecting miracles but I don't really understand why you would have two thermostats if they heating won't come on until both are below temparature.

 

[jackthom]

Do you have a combi boiler and are there any valves like this in the house ?

Untitled

• jackthom
• 4 Nov 2011
• 5

If the house has been zoned properly there should be a couple of these. Each will be controlled by one of the two thermostats to allow the heated water to circulate only through the part of the house where heating is required.

The way yours is working at present sounds like you simply have 2 thermostats wired in series, so they both have to be calling for heat to get the boiler going.

When the upstairs thermostat is set to a high temperature and the downstairs is set very low, does the boiler fire up and which area of the house gets heated?

 

[nj69charlie]

Yes it's a combi boiler and I've not seen anything which looks like that, although would they be hidden under the floor boards or would it be attached to the radiator?

If this is the case, then I expect when the ground floor thermostat is activated the boiler should fire up, but from memory it will only fire up when the upstairs thermostat kicks in.

When I get home I will have a play about and then reply with a more accurate description.

 

[jackthom]

They'll probably be mounted somewhere not far from the boiler, where the pipework splits to supply the two areas, upstairs and downstairs.

Not on radiators and hopefully not under floorboards, it should be somewhere the valves could be easily serviced if required.

 

[Diyisfun]

Might be worth speaking to the builders. If its wrong let them sort it.

 

[nj69charlie]

Ok so I have had a fiddle with the thermostats

When the upstairs thermostat is lowered and the downstairs is above the chosen temp the boiler kicks in and the whole house heats up.

When I raise the temp upstairs and lower the downstairs one so the boiler switches on it heats upstairs only.

That can't be right, something isn't working properly.

I've had the plumber out and they say there's nothing wrong with it, but I can't work out why it doesn't function as it should.

 

[jackthom]

Is the upstairs in your house the living area, with the bedrooms downstairs?

I could understand the living area always being in the loop whenever the heating is on and the bedrooms only being supplied with heat when required.

Not as flexible as both being entirely independent though.

 

[nj69charlie]

No the living room is downstairs and the bedrooms upstairs.

It just doesn't seem to make sense. It seems daft that when its cold downstairs the heating comes on upstairs. And when I want the heating on at night and want to heat the bedrooms the whole house heats up.

It defeats the object of having two thermostats

 

[jackthom]

to confirm from your earlier post..

with only upstairs thermostat switched ON only the upstairs is heated

with only downstairs thermostat switched on both areas are heated

I wonder how the plumber justified that.

 

[nj69charlie]

No the other way round

Upstairs therm on = whole house heated up

Downstairs therm on = upstairs house heated, downstairs heaters cold.

 

[jackthom]

So the downstairs thermostat controls the upstairs heating ??

 

[nj69charlie]

Yeah mind boggling isn't it.

I tried switching the thermostats over as I wondered if they were the wrong way round but all that did was stop all the upstairs heaters stayed off

The plumber came round, swapped them back and told me to leave them alone and it was working properly. He didn't stay long enough to check out the different zones as he automatically presumed he had fixed the issue.

I will have to get them to come back and sort it out properly. Just frustrating when you have to take time off work to get things sorted and now I will have to have them come out again

 

[picasso]

I reckon one of the valve end switches isint making so the valve opens but does not fire the boiler, when the other zone valve opens it fires the boiler and heats both zones. maybe