Plumbing in a radiator - leak free 3rd time lucky?

[Nozzle]

I'm trying to plumb in a "The Radiator Company" column radiator, I think the fittings are all good quality there's no particular problem with any of it. However some of the joints are weeping.

I initially used PTFE wrap around the threads which seemed to work find under a pressure test I did months back with compressed air (2-3 bar) but when I came to fit the radiator last night there are weeps from some of the joints.

Drained down, adjusted, re-filled and pressurised - still weeping but much better. Left it on for a few hours hoping (!!!) it might silt up a bit or the expansion/movement close off the gap. Nope. Drained it all down again, re-fitted all the fittings and bosses this time with hawk white. A little better, it's dripped 5mm deep of a paint spray can lid in ~8hours.

Should I take it off and start again, or will it silt up? Draining it down is a pain in the arse, and I could equally disturb the other joints. What is the experience out there with these small weeps??

Nozzle

 

[Gas2Air]

Silt up? I weep for you.

 

[terryplumb]

Assuming the leaks are on the threaded valve tail / to radiator tapping ,how many turns of PTFE tape are you wrapping around the valve tail thread ?? Not enough = leak
Too much. = leak.
I always put the valve tail into the rad without tape first ,to get a feel for how loose it feels , they do vary somewhat. Then decide how many turns to use. 12 turns is my starting point ,but many times over the years I have had to use more than that ,and yes its a pain in the ***** to have to drain it out and do it again .

 

[Nozzle]

After the first attempt I have dispensed with the PTFE entirely, cleaned out the threads and started again with the jointing compound. The results are much better but still imperfect. Must have been 3-6 wraps, not too much just enough to bulk out the threads.

Gas2Air - any man who thinks his coolant is pure water without sediment or contaminants is a fool.

 

[Nige F]

After the first attempt I have dispensed with the PTFE entirely, cleaned out the threads and started again with the jointing compound.

you need a few strands of hemp with the compound.

 

[Nozzle]

I did wonder - but the instructions suggest only if greater than 25mm fittings!

Nozzle

 

[Nozzle]

Instructions for the rad:
"...Bushes require a dry fit connection only; you must not use any Compound material (e.g. Jet Blue) of Plumbers Hemp. If you choose you may use up to 4 turns of PTFE tape to help seal the threads."

Instructions for the valve:
"Apply PTFE tape evenly to the valve tail thread. Do not use hemp. Do not apply too much PTFE as this can prevent the thread tightening fully home".

Which very much validates my original, but failed method. I'll do the same again.

I wonder why the manufacturers of this valve and rad are so against the hemp & paste?

Nozzle

 

[echoes]

Do as @terryplumb said. About 12 turns of PTFE wrapped anti-clockwise looking towards the rad.

 

[gasbanni]

Do as @terryplumb said. About 12 turns of PTFE wrapped anti-clockwise looking towards the rad.

I had to think about that ! And what I do ........to the original poster ...the threaded part is held horizontally in your left hand with the thread pointing towards your right hand which is holding the PTFE. your finger is through the hole in the reel, the loose end hanging down away from you. Start the loose end at the very end of the threads on the side nearest to you. Then going clockwise with the reel over the threads maintain tension on the PTFE reel and holding the loose end of the PTFE with your thumb wind it around the threads move your thumb after the first lap maintaing tension wind the PTFE around the threads until they stop.
Your putting thd PTFE on the threads so it doesn't unravel but tightens as you screw it together ( apprentices trying to do it for the first time funny !).

Judge by dry fitting it how much you need.....a loose fit a lot of PTFE ....tight fit not as much. Once the PTFE is on the threads spin it between your thumb and index finger a few times it forces it in to the root of the thread and you can start to see the thread form through the PTFE.......not only diyers have to do it more than once !!!

 

[terryplumb]

I never said anything about anti clockwise ,gasbanni has given you the way to do it , quite comprehensively too, and its exactly the same method as I use.

 

[Nozzle]

MANY years ago, when at school I did a day release (that's all, I'm not claiming to be a guru on i!) to the local college who gave crash courses on some trades. A dab of car maintenance, shoe making, plumbing. On that course, I picked up making basic joints, so just applied my hazy memory of that to this installation. PTFE was wrapped "in the direction on the nut", so as the nut is screwed on it doesn't pick-up the flap of tape as it goes around. Therefore any talk of clockwise, anti-clock wise, left and right hand etc doesn't need to apply, particularly as this radiator, as perhaps many are (??) has left handed-threads on two of the four boses.

I've now wiped the paste of the joints that were NFG, re-applied tape tightened it all up and now having a snack before filling and testing for leaks...

Nozzle

 

[Nozzle]

Success

What a ball ache

Nozzle

 

[Hot&Cold]

I always put the valve tail into the rad without tape first ,to get a feel for how loose it feels , they do vary somewhat.

The thread quality can vary a little, have found that while fitting imported designer column radiators the valve tail appreard loose compared to the stelrad planar radiators fitted with the same valve tails on the same day.

The designer column rads we were asked to fit were made in China and sold labelled with a very British name by an importer,looked great but did not work that good.

The trick for a first time watertight join is correct application of ptfe,no problem for experienced installers .

 

[FiremanT]

I always put the valve tail into the rad without tape first ,to get a feel for how loose it feels , they do vary somewhat. Then decide how many turns to use. 12 turns is my starting point ,but many times over the years I have had to use more than that ,and yes its a pain in the ***** to have to drain it out and do it again .

Terry, are you speaking specifically column rads or generally. ? At my age, I dread to think of how many valve tails I have fitted,and have NEVER "tested"in that way. I cannot recall ever having a leak.

 

[terryplumb]

Generally fireman T. Many many years ago when I was in my teens ,I had the good fortune to work with an engineer ,RAF trained and meticulous in everything he did ,which I suppose you had to be. Any minor infringement , including handing him a dirty spanner led to " if you did that working on an aircraft in the RAF you'd be in the glasshouse " . one day I asked why are there so many different threads why not just have one thread in different sizes for everything , that kicked off the lecture !! Part of which was along the lines of when a manufacturer mass produces anything with a thread the stock or die can not be in the same condition at the end of the run as it was at the start ,thus the quality differs in terms of the sharpness and depth of the thread.mostly going un noticed in most everyday applications ,but not good enough for the RAF . anyway its Just one of those things that sticks with you .so I try the thread first and if it feels loose use more than 12 turns . so fireman T , do you wrap the same amount everytime , how many turns ? Regards terry.