I have a slow drip on my rad where the valve tail screws into the rad...I have tried ptfe tape also tried ptfe paste (Goldseal) with hemp, Boss white with hemp but the drip remains...Any ideas on a cure ?? The system is a combi with a working pressure of 2 bars...
Generally PTFE works - if layered up to produce a gradually increasing thickness, it's hard to see how it won't give a watertight seal between non-deformed parts. However, if one (or both) of the parts have become deformed such that the gap is no longer uniform, I've found "Instant Gasket" excellent. Bought from a "Halfords", it is intended to produce a water-tight seal where the gap may not be perfectly uniform. I usually run a bead around the top of the thread, let it dry, and then apply layered PTFE tape as normal.
Thanks for the reply...I do that with the Goldseal but it still leaks. When I was working I used goldseal on steam pipes at 100lb pressure and it was solid.....I have been out of the trade for 15 years and wondered if there was any additive I could put in the system to seal it like radweld is supposed to do an a car radiator ??
I've never found it necessary. Nice, clean, bright, corrosion-free threads plus PTFE tape works very much most of the time. I've only needed more where one part or both had got distorted. I suppose that you could apply "instant gasket" to the thread and tighten the joint whilst it was still wet..
However, for just one leak on one radiator, I wouldn't risk compromising the while system by adding something deliberate designed to block "holes" up. It might "decide" that a pump, or valve needed "fixing" too.. not to mention the inside of the boiler..
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