On Mon, 15 Feb 2021 16:52:59 +0000, Davidm
wrote:

On Mon, 15 Feb 2021 14:02:20 +0000, Caecilius
wrote:

On Mon, 15 Feb 2021 13:27:15 +0000, Davidm
wrote:

On Mon, 15 Feb 2021 13:19:18 +0000, Caecilius
wrote:

On 15 Feb 2021 13:10:00 GMT, David wrote:

On Mon, 15 Feb 2021 12:21:54 +0000, Caecilius wrote:

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?

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.

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.
There is an adjustment in the valve body, but you need a special
Drayton tool to use it.
See here
https://www.draytoncontrols.co.uk/si...missioning.pdf

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.
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.

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