Drayton RT212 TRV head broke off - problem solved.

[318Mike]

History; Over a 15month period I changed all my Central heating radiators. The replacement radiators all came with a free Drayton RT212 thermostatic valves. The hot water and central heating system has worked perfectly since.
But a few days ago an RTV valve head was bumped by the hoover and snapped off!
Examination showed a tiny weep of water coming up the valve stem. Attaching an old blue transit cap overnight confirmed the leak.
Removing the valve (the smaller hex) revealed two black rubber O rings, with the lower ring twisted and partially crushed.
I replaced both O rings, tested the valve over 4 days and I have no leakage with the new RTV head working perfectly.

The O ring seals I used were Nitrile 70 from Simply Bearings = 1.5mm thick x 10mm & 2mm thick x 3mm. Cost was £3.45/10
A replacement Drayton RT212 Integral Sensor Head from Screwfix = £10.96 vat inc.

I hope this is of assistance to anyone with similar problems.

 

[SpongeBaldrick]

I'm in a similar boat - found at least one RT212 spindle weeping. I think I already know the answer to this, but did you have to drain down to replace the o-rings? Thanks.

 

[318Mike]

I'm in a similar boat - found at least one RT212 spindle weeping. I think I already know the answer to this, but did you have to drain down to replace the o-rings? Thanks.

No.
I allowed the system to cool, removed the valve and replaced the rings and new RTV head as in my post.
Without a lubricant the new rings make inserting the valve a bit stiff but a small pot of O ring grease is available from Simply Bearings for a few £s which made it easy.
The one thing to avoid is damaging the new O rings for the sake of a smear of O ring grease.