Room Stat Advice Needed.

[Marko11]

Hi all.

Have come on here for some help and advice.

My room stat, working fine last winter, thinks that the room it was located in (hallway) is 23 degrees (thermometer says currently about 16 degrees). Consequently I cannot set the stat to call for heat from the boiler if it drops below 23 degrees.

Boiler was serviced a few weeks ago. Baxi Platinum Combi 33 HE A. Installed as new November 2013.

Room thermostat WAS a basic Drayton analogue dial stat until last week. NOW is a Salus RT200 'electronic' room stat.

I noticed the issue last week, and thinking the old drayton stat was stuck/faulty, I ordered a replacement.

I have wired in the new stat exactly the same as the old one. Live, Neutral, Switched Live, and a parked earth. The 3core+Earth cable has not been touched. The stat is fitted in place of the previous one.

The problem still persists.

The new stat actually has a LED that shows when it calls for heat and this clicks on, but this is still only occurring at about 23 degrees, and like I said the hallway is colder.

The boiler is set to ON, not timed.

The room temp reached approx 14 degrees last night and the stat wasnt clicking in to call for heat at all when I turned the dial higher

Could servicing the boiler have caused an electrical supply issue to the stat? It's odd that it 'works' to a higher temp and calls for heat at 23 degrees. Its also strange that a new stat did not fix the issue.

Any ideas?

 

[Sharpend]

On the radiator in the room what valves are fitted? If they are TRV type then could be overiding stat? Or stuck? Had you tried opening the windows/doors to the room to let natural cold air circulate?

 

[Marko11]

Hi Sharpend, thanks for replying.

All rooms/bedrooms have TRV's on the (apart from the control one in the hallway where the stat is located) They seem to be working fine.

Cold air will set the stat on, but still will not reach below 23. It's clearly not that temp.

Am at a loss to think what else is the issue!

 

[steptoe]

Has the stat been bypassed at the boiler during servicing, and it's internal stat is what is kicking in? 

 

[NozSpark]

Did you remove the control knob when you fitted it?

Some room stats have a splined shaft that makes it easy to refit the knob in an incorrect position,,,, or allows you to adjust the stat temp to the room temp

 

[Marko11]

Did you remove the control knob when you fitted it?

Some room stats have a splined shaft that makes it easy to refit the knob in an incorrect position,,,, or allows you to adjust the stat temp to the room temp

Hi

Control knob not removed. Just new backplate fitted and wired in as before. The problem was there with previous stat, and persists with this one.

 

[Andy™]

probably something at the boiler end then

 

[Marko11]

Has the stat been bypassed at the boiler during servicing, and it's internal stat is what is kicking in? 

Not sure.

Will have to ask the person who serviced it if they touched the stat/connections.

 

[Sharpend]

On the back plate that you have wired what terminals have you connected too? 1 is generally live in, 3 is usually switched live out. It may be that you've connected the stat so that it works as a cooling stat?

 

[Steve3948]

Sounds like the Set-back is set too high.

 

[Evans Electric]

The back plate is probably a common plate , did you move the connections to match your new stat  or just remove the Drayton and fitted the new one ? 

What is the setting of the boiler stat ?

 

[Marko11]

On the back plate that you have wired what terminals have you connected too? 1 is generally live in, 3 is usually switched live out. It may be that you've connected the stat so that it works as a cooling stat?

Hi

I wired the NEW stat in exactly the same way as the OLD stat. The backplate is the industry standard type as before. The OLD stat was working last winter, but didnt recently so was changed for a new one. The problem hasnt gone away. Live, Switched Live, Neutral and the parked earth are in the correctly marked terminals.

I have just turned the dial to 25 and the boiler has fired up. The house is hot, and the stat has clicked off when it reached that temp. I have turned the dial back to 18ish and it is cooling. Issue still remains when house cools down, the stat wont call for heat as it doesnt unless higher than 23.

The back plate is probably a common plate , did you move the connections to match your new stat  or just remove the Drayton and fitted the new one ? 

What is the setting of the boiler stat ?

The old backplate from the Drayton had the same markings in the same positions. However I did install the new backplate for the Salus as fitting the new front too. Wired like for like in correct terminals.

The dial on the front of the boiler is set to 65 for central heating output.

Sounds like the Set-back is set too high.

Hi

The room stat doesnt have a setback setting.

 

[NozSpark]

If you can then, without breaking it, adjust the knob until the stat turns on and then pull the knob off and refit it but with the temp at whatever the room temp is

 

[steptoe]

Just sounds like the calibration is out then,

Do as Noz suggests and move the dial. 

 

[Marko11]

One further point, this happens regardless of having the boiler on or off. ie, with the boiler on, the stat will call for heat at 23ish degrees. With the boiler off, I can turn the dial past 23 and the stat will click in to call for heat. It works in the same way as the previous stat did.

If you can then, without breaking it, adjust the knob until the stat turns on and then pull the knob off and refit it but with the temp at whatever the room temp is

Just sounds like the calibration is out then,

Do as Noz suggests and move the dial. 

My concern here is that the SAME problem was occurring with the previous stat, the Drayton that had been working fine until recently. That was clicking in at 23 only too. This new one is brand new yet has the same problem as the old one?

I'll try and see if I can remove the dial.

 

[steptoe]

is the stat in dead air?

ie, is it in a corner

 

[Marko11]

is the stat in dead air?

ie, is it in a corner

No, It's in a hallway. It has worked for years just fine, yet didnt recently, so was replaced and problem persists.

 

[Steve3948]

Seems if they both clicked at 23 it's because it was 23, and you are basing this as being incorrect because you have a thermometer which say's it only 16.

My hallway thermostat is about 5 degrees out according to the wall thermometer that's just to the right of it but slightly higher.

What height is you stat and your thermometer ?

How do you know it not the thermometer that's incorrect.

 

[Marko11]

Seems if they both clicked at 23 it's because it was 23, and you are basing this as being incorrect because you have a thermometer which say's it only 16.

My hallway thermostat is about 5 degrees out according to the wall thermometer that's just to the right of it but slightly higher.

What height is you stat and your thermometer ?

How do you know it not the thermometer that's incorrect.

Hi

The thermometer is a mercury filled one. It is correct. The baby monitor also says the temp is same. Thermometer next to stat on wall in hallway approx 1m60cm.

Am beginning to think there's a logical explanation.

Thanks for all your suggestions/comments today.

I'll leave it there on this forum for now, but will keep trying to solve the issue...

Cheers guys and gals.

 

[roys]

The stat is not above the radiator is it? Or have you changed your front door for a new one with a window in it and a sun beam is now shining through hitting the stat?  Just trying a bit of lateral thinking