Drayton TRV4 sensor head & valve life expectancy

[Caecilius]

I've got about 18 radiators with Drayton TRV4 valves. I'm not sure how old they are as I can't see any date stamps, but I suspect they're about 20 years old.

I'm finding that many of the TRVs shut off at a fairly low temperature (around 20 degrees) despite being turned up to MAX. Removing the sensor head completely solves the problem, so I suspect that some of the sensor heads are starting to malfunction due to age.

Is this a known issue with old TRV4 sensor heads and should I plan on just replacing the problematic heads, or does this behaviour often indicate a problem with the valve itself like the spring becoming too weak which means I should be considering replacing the valves in the summer?

[JohnP]

What I find annoying is that all the useful adjustment is between 2.5 and

1. They need a finer screw thread or some sort of fine adjustment feature.

[David]

There should be an adjuster inside - little brass screw which can be wound in and out.

If the screw can be wound in further then the maximum temperature may go up.

Cheers

Dave R

[Caecilius]

I can't see any adjustment screw on mine - the only adjustments I can see are the temperature setting on the main body of the head, and the limit pin & holes on the underside. There doesn't appear to be any non destructive way to dismantle the sensor head.

[Davidm]

There is an adjustment in the valve body, but you need a special Drayton tool to use it. See here

[Caecilius]

Thanks for that - very useful info.

Looks like I should check these settings and maybe replace the gland seals while I'm at it. It looks like screwfix have the tool & spare seals.

[Davidm]

I took one of these body sections apart a few months ago, just out of curiosity (as you do). The valve insert just has a number of different size rectangular cutouts, which can be turned to align with a fixed cutout in the body. Hence accurate lining up the pointer and markings is necessary. This allows the max flow to preset. The idea seems to be to do away with the lockshield valve, and make it more difficult for someone to tamper with the setting.

[Roger Mills]

Have TR4's always had this feature, or does this only apply to recent ones?

Mine are about 15 years old, and I don't remember seeing anything about this when I fitted them. I balanced my system in the conventional way by using the lockshields.

[Caecilius]

Sounds like the way the gas regulator settings on a bren gun works.

[Cursitor Doom]

I was just going to say that and you beat me to it!

[Cursitor Doom]

You have to be very careful with Screwfix stuff. I'd find another supplier if I were you. They don't half sell some crap.

[Cursitor Doom]

Why would anyone want to do that?

--

"Andrey Semyonovitch really was rather stupid; he attached himself to the progressive cause and 'our younger generation' from enthusiasm. He was one of the numerous and varied legion of dullards, of half-animate abortions, conceited, half-educated coxcombs who attach themselves to the idea most in fashion, only to vulgarise it and who caricature every cause they serve, however sincerely."

- Fyodor Dostoevsky

[Roger Hayter]

Mine are usually between 3.5 and 4.0. Perhaps I like the house warmer?

[JohnP]

Roger Hayter [e-mail] wrote in news: [e-mail]:

I fine tune mine by listenening to the flow of water. When th room is at the right temp I expect to hear the flow being cut off.

[Caecilius]

I guess the idea is that you can balance the radiator using this setting, which then doesn't need to be changed. If you use the lockshield valve to balance, this setting can be lost when the valve is closed to remove the rad for decoration.

Anyway I think that's the theory. Not sure how well it works in practice.