Drayton TRV leak - Can it be fixed?

[Angling mad]

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Hi All,

Just had the boiler serviced and the guy played around with the pressure as he needed to just the boiler down in order to service change a part not sure exactly why as the part was the "ignitor" which he said goes regularly on the WB 42Cdi Combi and mine was on borrowed time. Anyhow today I noticed a couple of drips appearing by sheer luck on the lounge carpet, took off the Thermostat head and it was very wet see photo. It was done up nice and tight to the valve head and having wiped off the gunk from round the threads, fired up the heating it seems to be holding OK without the head on. I checked the system pressure and it was bit high at 1.5 bar so reduced this back down to just over 1 and will wait and see how it goes. However, if it does continue weeping I am guess the only fix is to drain down and replace the valve as do not have any experience with a pipe freeze kit.

[arco_iris]

The thermostatic head, that you have pictured, does not have any water in it - for it to be wet, the leak is from the tiny pin in the top of the valve body. When you have removed the head, the pin is fully up so the valve is fully open. The flow circulating through you c/h pipework is flowing through at maximum, apart from when the overall pressure is high (as you described) the flow is not having a chance to weep.

Try pressing the pin in with a hard object, see if it leaks then.

So it is likely that the pin is weeping when partially down, and the ONLY way to fix this is to drain down the system and fit a new TRV of the same type (which will then be a straight swap).

[chrrris]

Just as an aside. I will NEVER fit another Drayton TRV unless a customer specifically asks me to (under the advice that I think they're rubbish). I am sick of replacing them. I'm not sure if it's just a bad batch or what, but for the past year or so, I find the plastic goes brittle and the heads break off in a matter of months.

This one in the picture (an RT212) is one that I already replaced about 6 months ago (same issue as previously). It's broken off in the same place they always do. It's in a study, tucked away next to a desk in an unexposed area, in a house with no kids, and I don't believe it's ever been knocked or mistreated (in fact, I doubt it's even been adjusted since I fitted it). They're garbage. I think the plastic used is unable to handle the heat cycling. Similar problems with the other style with the red swash on them (TRV4). I'd be very interested to know if anyone else is having similar issues with them to be honest.

So if you drain down and fit a new one, I strongly advise against a Drayton.

[Angling mad]

Sounds like you have not had much luck so I can understand your views. I cannot complain about my TRV4s they have been worth the extra to me as they are 15 years old and this is the first problem I have ever had after having used them in my homes for 25years. Like most things these days though maybe their quality has dropped.

Since I have reduce the pressure and opened the valve the small weep leak has gone so the pressure is off for now but I will replace it over summer with the same TRV4 style to keep the same look.