TRV frost behaviour

[Tim Streater]

I discovered the hard way today that these things open at several C, not at near zero as I had assumed. Minor flood (rad is off for painting, and TRV is closed) but nothing serious as the newspaper on the floor mopped most of it up. Fan heater soon warmed it up enough to stop the water coming out.

May go out and score some rad caps tomorrow.

Now, this behaviour - is it designed just to avoid local damage to the rad or pipework, or is the idea that water should move round the system as well? Seems to me the latter would require the boiler to be involved too.

[dennis]

8<

It relies on the boiler and pump being on. They are pretty useless without a frost stat in parallel to the room stat and timer. They are designed to keep the room frost free not the pipe work.

[John Rumm]

Take off existing head, insert 5p coin, replace existing head. DIY decorating cap ;-)

They assume the boiler is also running on a frost protection program.

[ARWadsworth]

A friend of mine now caps the valve off with blank plugs. His TRVs actually had an OFF position but his 2 year old decided to play with the valves:-)

[Newshound]

What a great tip! Although I never throw anything away, I can never find the right shutoff-cap when I need it (have several different types)

[Tim Streater]

Take off existing head, do I not get water everywhere (rad is off)?

Right thanks - to be borne in mind if we rejig our CH.

[John Rumm]

Nope, the TRV head is only a wax capsule device that usually pushes down on a pin or peg sticking out of the top of the valve itself, it has nothing to do with the tap part of the valve - it just uses it.

It really just needs the programmer left set on continuous, and the room stat left at 5 degrees or so.

[Roger Mills]

YES!! You have to take off the head, insert the coin, replace the head and turn it fully off *before* you remove the radiator!

If the valve to rad joint is of the compression type, and if you want belt and braces, once the rad is off you can use a short piece of pipe with an olive and compression nut and end stop. Connect that to the valve and nothing will come out even if the valve opens.