TRV Valve head stuck?

In message , AnthonyL writes

Don't do what I did yesterday with a stuck pin tucked behind a heavy bunk bed: pull the pin right out creating a fountain of water:-(

Fortunately it went back in and sealed OK but it was an anxious few moments!

Frost setting will be furthest extended. Try poking it when set to hot and see if you get any movement. You could swop it for one from a less critical area. IANAP

The centre bit springs in and out but doesn't move as I change the setting from hot to cold. I've looked at one from a working radiator and the centre does go in and out with rotating so I guess this one is broken.

Probably. Just swap heads between a working and non-working radiator. If the non-working one then works, and vice versa, you'll know that the head is duff.

The movement of the female cone in the head isn't very much, or easy to see, but your diagnosis of a faulty head sounds right.

The usual failure is with the pin sticking in the valve, normally in the closed position. If you tap the pin axially with a small hammer, although this seems to be the wrong direction it often frees up the crud so that it springs out. (It doesn't normally come out completely!).

If the pin has a build up of crud it may have damaged the gland seal as well, resulting in a leak when you free the pin up. It's possible to replace the gland seal without draining the system, see here:

I phoned Drayton and they sent me half a dozen replacement seals and the tool to do the job, for free! There are a few places where you can buy them, but often out of stock. Google "drayton trv repair kit".

In message , Davidm writes

I wonder if Myson valves are as simple. Lots of limescale crud found while decorating.

Right - the head is duff. I've now been around all the radiators to check their condition. Good news is that all the valves go up and down though a couple took a bit (not a lot) more persuading but seem ok now. And the inside of the heads move when the top is rotated on all except the duff one. One radiator has a missing head.

I've got a mixture of heads, the acl Lifestyles, a Westherm, and a couple (which don't look old) marked E 29 (the E has a small o above it).

Two questions:

What are they for?

Anyone any experience?

In message , AnthonyL writes

er.. Do check that the *missing head* is intended to be there rather than a bodge providing an overrun bypass circuit.

What is "an overrun bypass circuit" and how do I know if that is what it should be?

A rad that should be always on and has no user control - so if the boiler needs to dump some heat and the pump is running, some flow can at least get through this radiator. Often found in a hall or maybe a bathroom.

In message , AnthonyL writes

Somewhere for the boiler water to circulate if all the TRVs are closed but the room thermostat or boiler thermostat have not shut down the boiler.

Different boilers/systems have different requirements. You need someone who knows more about plumbing than I do:-)

Both the rads in the hall and the bathroom require a spanner/pliers to adjust. The one with the missing head is in the kitchen which doesn't seem the best of places to have an 'always on'.

In my old, coal fired centrally heated, house the "always on" radiator was the highest and in the bathroom. That was on open system ie header tank. This house is a bungalow, closed condensing combi boiler.

If we are away for a few days when the temperatures are low I want to set most of the house to frost setting.

Don't know for sure, but they could possibly provide a way to set a limit stop which stops the TRV being turned up to too high a temperature.

Roger Mills wrote in news: snipped-for-privacy@mid.individual.net:

Most have a way of setting a max and/or min to prevent tampering.Mine have a pin that slides into an appropriate slot.

Roger Mills wrote in news:del83sFe88sU1 @mid.individual.net:

This looks handy.

Oh that the heads were so clearly marked :(

Yes there's a pin at the maximum end on this head though if I try to put it in a different position it won't seat - but maybe that's because this head's movement is broken.

It wasn't I who said that - something appears to have gone awry with your quoting!

In any event, that site only checks compatibility with ACL's rather expensive control gear - not with a simple replacement head.

The DerbyBorn post looks on my system as if it came from you. Apologies.