honeywell RF DT92 thermostat not working correctly

[roggalach]

I hope someone can help. A few weeks ago, the fuses blew in my house, it turned out that water was leaking on the switch in the manifold for the underfloor heating, and this was replaced.

However, since then the wireless thermostat is just not working as it should!

-Firstly, it is always seems to be reading 22'C (well mostly, occasionally it displays 22.5'C), which is odd.
-I have the stat set to come on if it hits 21.5'C, but occasionally I see the little flame symbol coming on when it's reading 22'C!!
The UFH just never seems to come on because the thermostat always thinks it's 22'C, but it didn't used to behave this way; in the winter it would often be on, especially in the morning.
- Also, I keep thinking I'm going bonkers, the floor feels slightly warm under foot, (when it shouldn't be on!) and then when I touch it, it is not actually on. But it feels like there's a low-grade flow of warm water somehow!

I've taken the batteries out and tried to reset, but nothing is making a difference.
Do I need a new thermostat?

Thanks!

 

[CBW]

Is the red led lit on relay/receiver?

 

[roggalach]

I'm not actually sure where this is. The manifold is in a basement under our kitchen, would it be with that?

 

[CBW]

You’re looking for something that resembles this:

Try looking next to the boiler or near the wiring centre

 

[roggalach]

It's not near the boiler. Will have to look in the basement when it's daylight! Will revert in the morning.
Thanks so much!
(What will I do if it is flashing red?)

 

[CBW]

If it’s flashing red,or even solid red it might have lost it’s rf pairing, which is fairly straightforward to rebind.https://heatingcontrols.honeywellhome.com/Documents/User-Guide/pdf/1074.pdf If it’s not,then could just be a goosed thermostat.

 

[roggalach]

Will check it out, but it strikes me as a strange coincidence that it got goosed just after the switch was changed!
Will go on a hunt under the house tomorrow.....

 

[roggalach]

Novice, I paired the two devices as described. But.... the thermostat is still acting up.
I believe it's misreading the room temp (I feel cold, and it's showing 22.0'C) and the fire symbol is appearing at a temp higher than I've set.
Do you think I need to buy a new thermostat? Anything else it might be?

 

[D_Hailsham]

As it is a wireless thermostat, why not try it in a different location? The current location may be a heat-trap so the thermostat is turning off earlier than required.

PS The thermostat is not somewhere unsuitable e.g above a radiator?

 

[roggalach]

Thanks very much D,
The thing is, I haven't moved the thermostat. It's been in this same location for over a year!
It's just acting really odd.
(It's not above a radiator; it's in the kitchen where the UFH is)

 

[roggalach]

Also, even if it was in a heat trap, it shouldn't be turning the UFH on at 22.0'C, when it's set to go on below 21.5'C
Also, it seems to always be 22.0, even though the room feels a different temp...

 

[CBW]

Do you have access to a thermometer?

 

[roggalach]

nope....

But tbh, I'm more concerned that it seems to be turning on at the wrong temperature.
And when it displays that it's on, I don't actually think the floor is getting warm!!

 

[CBW]

Also, even if it was in a heat trap, it shouldn't be turning the UFH on at 22.0'C, when it's set to go on below 21.5'C
Also, it seems to always be 22.0, even though the room feels a different temp...

Ok from what I’ve established, the room feels a different temperature, but no way of proving it (no thermometer). The room thermostat will only come on at a target temperature, so your saying it’s set to go on below 21.5, but if it’s registering 22 will be satisfied. So therefore if you set at 23, should fire up heating to 23, on room thermostat and turn off. Is this not happening?

 

[roggalach]

That's correct.
It does seem to fire up the boiler if I set it to be higher than the ambient temperature.
But I feel the floor didn't actually get hot once the boiler fired up!

If set to go on below 21.5, it shouldn't be ever displaying the fire symbol at 22.0 - even though I think this is false: it's showig thefire symbol but not actually warming the floor.