TRV - What happens at MAX setting.

I don't really know, but if you set fire to the room you could go in afterwards and check and report back to us all!

Julian.

Julian,

Many thanks - excellent advice - I'll do that right away.. Of course if anything goes wrong... I'll say you told me..:-)

It was a seriuos question. When set to zero they stay shut. Are they designed to stay open at their max setting?

Roy

Eaxmining two different heads, the motion is entirely linear, i.e. there isn't a point where the pusher suddenly springs out of sight. So I conclude that there will still be a temperature where it starts to close down. Conversely, even fully shut down it will open up if placed in arctic conditions which, of course, is required for frost protection. The head does have two separate positions marked for frost and off, but the motion between them is still linear.

Chris

Hmm - so even "0" is not "OFF" ... hmm

Although it might be that it only opens the valve after the water in the pipework is frozen solid... ;-)

Yes I know, sorry, couldn't resist.

It's a question that I haven't given much thought to and is really of academic interest only unless you've got money to burn! I would think that the answer would vary depending on what make of stat you have, and how hot the rad can make the room.

Mine (Myson) have a '0', '*' (frost?), then I, II, III, III and then a 'max' setting. They do appear to cool slightly on the max setting when the room is toasty. The ones I keep on '0' (bedrooms) have never come on

- but then it hasn't been that cold.

That is only true for some brands / models. Some only go down to "frost free" -when it gets cold they *will* open (so don't rely on that setting to isolate a rad position prior to removing it).

I do wonder if the typical treatment in CH has an effect on freezing points.

It probably has a small effect, but there are anti-freeze additives if you really need to protect against freezing. They're expensive because you need quite a lot, depending how cold you need it to handle.