room stat

[gk]

i have a problem with room stat if i turn it down it completely goes off if i turn it up to 20 it goes way above 20 each room is very hot

 

[bathjobby]

So whats the question !

These things cost a few pounds and usually have just 3 wires (or so depending on the type); Change it........

Remember, you probably have mains voltage in there so switch off first.

 

[Bahco]

If faulty change it.
It could be located in a very cold area which would mean it would not reach set temp and turn off heating when it should.
You could fit Trvs to most of your rooms if they are unbearably hot.

 

[keego]

I had one like this the other week, the tenant was complianing her flat was too hot & the room stat or zone valve was faulty. Turns out both were OK,but the rads were getting so hot that when the room stat shut off, the room temp went way past what she wanted.
So in the end I set the stat to 16c (she had it on 20c) & she was happy with that.

 

[felix]

Before you condemn your room stat check its connections. Inside the stat there is a large value resistor, maybe 470 kilohms, and its job is to heat up the bimetal strip but only when the stat switch is closed. The idea is to force the thing to cycle on and off. In this way, the room temperature doesn't have to swing up and down as it would if the stat was a simple switch. If the temperature drops, the heating spends more time on than off and vice versa. (Electronics engineers out there will recognize this as pulse width modulation.)

If the neutral connection is missing, the system doesn't work. The room has to get much hotter than the stat is set for before the extra heat gets to the bimetal strip to open the switch. It will then have to cool a lot before the thing closes. Of course the same thing will happen if that resistor fails.

You get the same large temperature swings if you wire a stat in backwards so that the resistor is always hot. I don't think you've got that problem because in that case the room temperature would be too low.