How can I stop a new radiator valve tail from leaking- help!?
Question:I'm trying to replace a radiator with a towel warmer. The system uses slightly flexible plastic pipes so I've been able to remove the radiator and connect the towel warmer straight away as the dimensions are similar.
The problem I'm having is with the threaded valve tails- all seems to screw together OK and I'm using PTFE tape wound the right way round. Every time I switch the valve on and bleed I'm getting leaks from the union nut joining the valve to the valve tail. I've tried re-doing it a couple of times, even with a new tail but to no avail. The nut doesn't appear to be cross-threaded or split or anything like that.
This is my first heating project so I'm hoping someone's got some tips on how to get a better seal.
Answers:
Is the leak flooding out or just a dribble? My 'other half' has just installed his first radiator and found a dribble even after adding the PTFE tape...but as we were busy with other stuff as well we just left a bowl under it...then after about 4 days there were no new drips and it seems fine now! Maybe worth leaving it to see if it will 'settle down' if it's just a little dribble...
If the unions have been re-used it is possible for rust to build up on the sealing faces of the two halves. What you need to do is split the unions and clean the two tapper cones on the union with sand paper. Some times the unions do not have tapper seals and us a gasket between the two flat halves. If this is the case make sure you have a gasket fitted as they can get lost.
If after re-jointing the now clean union there is still a leak, you will either need to replace the union with a new unit or use plumbing grease/sealant on the tapper joints.
Use PTFE 'gas' tape, its much heavier than the normal thin version. smear the tape with some 'Fernox LS X' (from homebase or good plumbers merchant) LS X is like a silicon sealant.
Use some plumbers teflon paste. (pipe dope) Not too much! it is normal to have a slight leak. It just means you have to tighten things a tiny bit more.
Make sure that there is no excess glue on the union surface.
You need to coat the seating of the union nut with boss white jointing paste available at most DIY shops or ironmongers. Although the two faces of the union nut are well machined, there only needs one tiny high spot to let water leak. When you apply the paste both faces must be dry.
try using fernox LSX which i very much reccomend
Make sure that the male and female union are the same make ,if not the angles will be different and you will never get them to seal ,and you should not need to use ptfe tape .
The most reliable way to seal your compression joints, is to loosely wrap PTFE around the pipe in front of the olive,(twice around pipe is sufficient). So that when you put the joint back together, the PTFE seals the gap between olive and fitting. Then re-fit joint, making sure not to overtighten.
Good luck...this works for me every day.
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