Altech ALTHC004 - radiators coming on when heating off

[abi10421]

Hi, I moved into a new house 3 weeks ago. I set the Altech thermostat as per instructions - at the moment it’s only set to go on in the morning for an hour as the rest of the day is set to 10 degrees (followed an online tutorial so know how to do this as there are several periods to set). However the heating keeps coming on in the evenings. When I went downstairs to turn it off the thermostat is reading 19 degrees. When I pressed the arrow down, it was definitely set to come on at 10 degrees so had to manually put down to 5 degrees to turn off radiators. This happens most, but not all, nights at around 9pm. I have no idea if it’s coming on overnight at all as I’m asleep but usually it is off when I go downstairs in the morning after it’s hour on set at 17 degrees. It’s only an issue at 9pm, the rest of the day it works as programmed. The boiler and receiver are situated in the garage off the kitchen - much cooler than the house as there are small gaps around the garage door so outside air comes in. Thermostat is in the kitchen.

Any ideas why this is happening and if there’s anything I can do to resolve it?

 

[Exedon]

That's a re branded Salus thermostat they are far from the best.
I'd be swapping it out for something far more reliable.
We use E P H combi pack 4 rf thermostats £55 zero problems.

 

[CountryFan]

Is there a frost thermostat fitted?

 

[abi10421]

Is there a frost thermostat fitted?

I’m not sure - there is a frost option on the thermostat if that’s what you mean? I’ve attached pics of what I’ve got as it’s all a bit over my head.

 

[ericmark]

I had a wireless thermostat sold under many badges, and it would fail to switch off, better quality wireless have an auto off if the thermostat not seen in ½ hour, but I walked into mother's living room, and it was around 30ºC where the top thermostat had stuck on, plus no one had set the TRV heads, so the thermostat was moved closer to the base, and I set the TRV heads, so if it did stick, all it would mean is the boiler will cycle on/off every so often.

If I manually changed the temperature, it would often respond, so did not realise what the problem was.

This house also had problems, there are three devices which can turn on the boiler. A Nest Gen 3 thermostat in the hall, a Wiser wall thermostat in the living room, and a Wiser TRV head in my wife's bedroom. All the other TRV's are programmable, but hers is only linked one.

I am still playing at getting temperature settings correct, but there is a cat flap in the hall, and we are training a new to us cat, and often peg open the cat flap, easy to forget, and a cold blast of air sets the Nest running, or wife forget, and leave a window open. Only when we hear the boiler running do I look.

Some of my TRV heads have a door/window open shut down, if the temperature sudden drops, it assumes a window is open and turns off. But even if the wall thermostat is faulty, rooms should not overheat, as the TRV should shut the supply off to the radiator.