Understand / tweak valve operation

[sebbacon]

Most of today, the actual temperature on the radiator in the study has been above the set temperature, yet the valve has remained open at 38%. This is possibly because the temperature has not started dropping, so it's considering this the maintenance level:

Green = actual temp Yellow = set temp Blue = valve open %

[sebbacon]

I've turned the boiler off manually. Let's see what happens to the valve state when the temperature drops.

[sebbacon]

So 30 mins after boiler was turned off, the actual temp measured by the thermostat when down 1 degree and the value opened by another 20%. (The cliff after that is because the program changes the set temp to 12C at 17:00).

It therefore looks like the TRV is trying to set a temperature at one or two degrees above the set, for some reason.

[sebbacon]

This morning I'm trying setting the temperature to 19C and checking what happens to the valve

[sebbacon]

That made the valve close. Now tried setting it to 20C.

[sebbacon]

Master bedroom was toggling on and off all night, when aiming for a temperature of 16C.

The rest of the house was at 18 - 20 all night, and our room didn't feel cold, so this is weird.

Possible explanations:

• The radiator is on an outside wall on the main road. Maybe the ambient temperature around the TRV is lower than the room temp
• Faulty temperature measurement

Best thing to do is move the wall thermostat to the bedroom (temporarily) to verify the TRV

[sebbacon]

It's not been as cold since then, so I'm not sure I've proved anything:

I did, however, notice that the window was slightly open (now closed)