Wall Thermostat fails to turn Heating Off

[headache56]

My conventional Ideal Standard Mexico boiler works 100% OK and it turns HW and CH totally off and on, exactly at the times I have programmed.

However, my house is getting very warm because (during "On" periods) the CH is not being switched off by the wall thermostat when the desired temperature is reached.

For example, today I have the wall thermostat set at an experimentally low level, 10c, but the radiators were all hot and were powering away, so I have just turned the whole system off. The wall thermostat (the bi-metallic strip inside?) "clicks" at about 20c. It feels as though the room temperature is about 23c.


Is the fault more likely to be (i) a sticking valve by the boiler (ii) a faulty wall thermostat or (iii) something else ?

 

[Diyisfun]

B4 The experts ask.
Has it worked ok previously?
What type of t/stat do you have?
If its a manual type, do you hear it click when you turn it up & down?

I am only a DIYer

 

[b16kvv]

Just because it clicks doesnt mean it actually works! Sounds like its defo down to the room stat so I would start by replacing that especially since your heating works fine from the manual controls on boiler!

Kev

 

[Diyisfun]

Just because it clicks doesnt mean it actually works! Sounds like its defo down to the room stat so I would start by replacing that especially since your heating works fine from the manual controls on boiler!

Kev

I know that, its nice to hear the click (it may be digital we dont know that yet).
The room stat is the easy one to check, especialy if you can get to the wiring & know what you are doing & can disconnect the wires.

 

[BingoBongo]

i would check motorized valve

 

[seco services]

as BingoBongo said worth checking the zone valve if its a s plan.

but then as headache56 said it turns HW and CH totally off and on, exactly at the times I have programmed.
providing the boiler still don't fire up after these times then i would opt for the stat.

 

[BingoBongo]

do you notice the rads getting hot when hw is selected?

 

[doitall]

Sounds to me like the microswitch is sticking/stuck in the MV as well

 

[headache56]

Thanks gents. I will replace the Sunvic manual room stat first, and if that fails, the m/v then report back. Cheers.

 

[doitall]

You can check all the parts electrically, there's no need to keep changing parts until you strike it lucky.

Of course if you have deep pockets and money is no concern, carry on.

 

[bengasman]

I will replace the Sunvic manual room stat first, ..

Get a decent one whilst you are at it; a honeywell only costs a couple of quid more.

 

[b16kvv]

I know that, its nice to hear the click (it may be digital we dont know that yet).
The room stat is the easy one to check, especialy if you can get to the wiring & know what you are doing & can disconnect the wires.[/quote]


Easy tiger settle down I was suggesting replacing room stat only no need to get huffy!

Kev

 

[D_Hailsham]

What type of t/stat do you have?
If its a manual type, do you hear it click when you turn it up & down?

The wall thermostat (the bi-metallic strip inside?) "clicks" at about 20c.