A Question on radiator TVR

MikeJXE

Something has bugged me for a long time and I read on here about the use of your TVR controlling your radiators 

Scenario

I have a small thermometer on my table stating it's 18 degrees in my lounge 
I move that to a radiator thats on and it rockets up.

I understand a TVR is like a thermostat but apparently works with wax 

If my TVR is set to allow a temperature of say 18 degrees 

How does it differentiate  the  temperature I want in the room and what it's fixed next to. 

Your answers will be much appreciated 

BUFF

there are both wax & liquid TRVs (liquid tends to be faster reacting).

It won't, there most likely will be a differential but they are roughly calibrated to allow for it (some eTRVs will allow you to input an offset to make that even more accurate) & ideally the actual sensor head is held as far away from the radiator as possible (horizontal heads tend to be better than vertical heads for this). You can also get TRVs with remote sensors.

FreeBear

[Deleted User] said:

MikeJXE said:

How does it differentiate  the  temperature I want in the room and what it's fixed next to. 

The answer is probably "not very well" ... but they're better than nothing.

And if you have restricted airflow around the TRV (because of furniture or clutter), the TRV is even more wildly inaccurate.

If you want precise control over what temperature the radiator turns off, then you need a smarter (and more expensive) control - I had briefly considered using some mains or low voltage wax motors (as used to control an underfloor heating system) along with some "smarts" hooked up to a home automation system. At the end of the day, the cost & complexity wouldn't save any money on heating and only scores a few geek points.

markin

The simple answer is to set it by using a thermonitor rather than the number on a Dail and what the manual says it should be.