Thermostat Stopped Working

[jay8ee]

Hi all.

I moved into my new house a few months ago, and up until yesterday everything had been fine with the central heating. I noticed yesterday the heating downstairs no longer comes on.

Some details on the system. I have a 'Ideal Logic 35' combi boiler. The central heating is zoned so that upstairs and downstairs are controlled separately. Both upstairs and downstairs are controlled by separate 'Heatmister Slimline PRT' thermostats.

The boilers burner clicks on when the upstairs thermostat shows the flame icon, and therefore is a demand for central heating. Also, when I run any of the hot water taps in the house, the burner also clicks on as it should.

For some reason the boiler is no longer responding to the thermostat that is downstairs. The flame icon is lit on the thermostat, but the boiler does not click on anymore. It's like the boiler is not hearing the thermostat. The only reasonable thing I can think of is that the connection to the boiler and the thermostat has severed somehow, but I have not been messing around with any of the electrics in the house.

Is there anything else it could be?

Many thanks in advance.

 

[TCCHeating]

More likely to be one of these

 

[jay8ee]

Is that the valve that would control the flow around the downstairs loop?

I suppose if that isn't opening then this would be the reason that the burner doesn't click on also? I guess it only clicks on when it detects water flowing though the system.

 

[muggles]

Does the zone valve motor across when the PRT calls for heat?

 

[muggles]

Is that the valve that would control the flow around the downstairs loop?

I suppose if that isn't opening then this would be the reason that the burner doesn't click on also? I guess it only clicks on when it detects water flowing though the system.

Not quite, that valve is what turns the boiler on via an internal microswitch

 

[TCCHeating]

You will have 2 of them. One for upstairs and one for downstairs. You will need to get an engineer to test if it is the valve or the thermostat that is faulty.

In the meantime. You can lock the downstairs valve open so that your downstairs heating comes on when the upstairs thermostat is calling

 

[jay8ee]

More likely to be one of theseView attachment 91833

I've just gone and had a look underneath the boiler, I cannot see any components that look like this. Are they normally located near the boiler? I can't imagine where else they would be.

 

[TCCHeating]

Normally on the flow pipework from the boiler. But can also be on the return.

As to where they are. That's anyone's guess! But you would have thought that the installer has fitted them somewhere accessible

 

[jay8ee]

Yea I hope this is the case! otherwise this is going to be a pain.

I just found some docs in my house pack. According to the docs the motorised valves are made by 'Drayton'.

 

[TCCHeating]

They will be white then.

 

[jay8ee]

Thanks everyone for the help.. I am going to try and find these valves, so I can hear if the motor is working.

Surely they weren't installed within the walls....

 

[Echo the husky]

Just out of interest, where in the UK are you, there is a site of newish houses near me with this setup, several of the thermostats recently failed within a month of one another, almost as if they were programmed to fail after a set number of hours...

 

[jay8ee]

Just out of interest, where in the UK are you, there is a site of newish houses near me with this setup, several of the thermostats recently failed within a month of one another, almost as if they were programmed to fail after a set number of hours...

Interesting. I am in the West Midlands. Not a brand name developer though.

 

[Echo the husky]

No where near me then!