On Tue, 17 Sep 2013 20:20:24 +0100, "harryagain"
wrote:


"Davidm" wrote in message
.. .
On Tue, 17 Sep 2013 11:07:34 -0700 (PDT), John G
wrote:

On Tuesday, 17 September 2013 18:48:32 UTC+1, Davidm wrote:
I fitted new Drayton TRV4 radiator valves to all my rads about 4 years

ago, and already two of them have started leaking where the valve pin

projects from the valve body.

Is this a common problem? Are they fixable or is the only solution to

renew the whole thing? Anyone have a magic solution for doing this

that avoids draining the system (it's an open vented system with a

header tank)?

Most valves have a gland nut on the valve body that can be tightened
slightly to stop the leak BUT not too tight to stop the pin moving.
No gland nut on thse valves, the operating pin just projects through a
plastic insert in the top of the valve body (unless the nut is inside
the valve body - which would be pretty useless anyway).

It probably has an O ring. Some have PTFE packing.
Supposing you can get one, they can be replaced but sometimes they still
leak.
It's quite unusual to leak so soon. Have you got inhibitor in the water?
Could be a corrosion problem.
You'll likely end up replacing them. May as well wash the system out and
make sure you have inhibitor in.
Many inhibitors claim to have lubricators as well.

It's a good idea to "exercise" the valves by winding open and closed now and
then. (Keeps the spindle clean)

The best valves BTW have a bellows not an Oring.. Expensive.

Yes system has inhibitor in. I fitted the new TRV's just before a new
boiler was installed, and the whole system was power flushed at that
time (by the boiler installer - qualified plumber).

Looks like I'll just have to replace them. Exercising the valves is a
good tip - thanks.

I did look at the more expensive valves - OUCH! Even the TRV4s are
quite a bit more expensive now than when I bought the last lot.