How to fix a dripping radiator...

[Geminineil]

Can anyone help.. in the absense of finding a plumber.. having a go myself.. to replace a few radiator thermostatic valves that are past their sell by date... of course first thing is the 'dolly' (I believe it is called that) needs changing in the side of the radiator as it is a different size to the new one...

having 'bunged' the heating expansion tank.. and low and behold gravity vacuum worked! (phew) but having put it all back to together and with ptfe tape around the dolly boss.. (about 6-8 times) drip drip drip... from end of radiator... about one drip every 15 seconds... (30 minutes later one drip every 30 seconds)

Q1 how many times should I wrap the ptfe tape around..
Q2 is it feasible with expansion of pipework that dripping will stop (why do I think not)
Q3 any other solutions? (apart from trying to find a plumber....)

for the moment one small cup at the end of the rad....

 

[andyg0507]

have you tried tightning the nuts a little more to see if they grab the olive better??

i usually wrap ptfe tape round 10 times.

but thats just me

 

[Geminineil]

I have tried tightening... and re-tightening.. is it feasible to 'overtighten'?

Now sure if trying to put tape in the joint would help? Also, should the tape always be put on 'flat'? and not rolled up?

silly question... but does the ptfe tape 'melt' into the threads once heated? the rad started with one drip every 15 seconds... now having run the system for an hour is 1 drip after 1 minute 15 seconds...

 

[secret squirrel]

Hello,

Congratulations on getting the vacuum working, I'm impressed, did you hold your breath as you were working (I normally do)

PTFE tape in joint will not help as water is already seeping. What I would do is re-do the PTFE around the joint, Yep! re-do vacuum and do that bit again. In my experience PTFE tape is a bit hit and miss, I do put quite a lot on about 10-15.

Nope, can't see it stop dripping just do it again. You'll be happier with the result.

 

[so-solar]

make sure you wrap the ptfe clockwise or else as you screw it in it just unwraps from the thread, grab a small pot of jointing compound too!

 

[Geminineil]

I have to say that having drained the water from the radiator... which seemed to take forever... and then removed the old stuck valve and a surge of water coming out of there briefly... so a panic moment.... I did wrap the tape clockwise.. although... is this clockwise looking 'along' the thread.. or clockwise looking into the end hole of the male thread? I did the former... methinks therefore I may have put it on the wrong way around.. oh well will re-do it when I do the others....

 

[Bernie2]

Never heard a rad valve "tail" called a "dolly" before. Wrap the PTFE the opposite way to what you screw the tail in.

The idea is that the end of the PTFE doesn't pick up and turn off the threads. So if its right hand thread put the tape on left hand or anti clockwise, so that the end is pointing away from the direction your turning.

A bit of jointing compound helps as well. But try and avoid getting it inside the rad.

 

[stevetheplumber]

Drip has slowed due to the heat expanding the metals and closing gaps it will drip again when cold as said at least a dozen turns with ptfe abd a bit of white paste on the top of the tape

 

[migoplumber]

nobody using hemp nowdays on rads??

 

[so-solar]

I am and swear by it, alot people have forgotten or dont even know what it is though migo!

 

[feltham]

im not a fan of hemp and boss white gets quite messy and end up wiping it down my leg to get it off. ptfe is easy i dont think i have had a prob with a rad tail befor. always a first tho.

 

[Renewable M]

love the point about clockwise, solar! how easily we miss the obvious.

 

[Smcart5]

Ten turns of ptfe, turn it round the same way you turn the nut to tighten, not sure if folding it is a good idea.

I was taught at the college course to use ptfe on radiator valves and only use hemp on steel joints, is there anything in the water regulations about hemp+copper?, or central heating systems?

 

[WHPES]

Hemp every time, but I tend to use Stag paste rather than Boss white (my oil engineer background!). I run a coarse file across the top of the threads of the tail just to give it a bit of extra drag.

Water regulations - you can't use hemp and non potable water paste on potable (drinking water) and its supply but you can use Water Hawk and hawk fibre. You can use hemp and boss white / stag anywhere on a heating circuit. More reliable than PTFE.

 

[NickH]

I always use loctite 55 ptfe string now, much stronger than normal ptfe tape so it doesn't shred.

 

[Geminineil]

Can anyone help?
Having replaced an old radiator thermosatic valve using the 'bung method' I thought I would have a go at doing another two tonight... I accidently left one of the valves open one end... and also am not now sure whether you should do two at once using this... bottom line is,.. gas Netaheat boiler ran briefly... lots of knocking in pipes.. ie air... and now the boiler will not run for more than 10 seconds or more.. I can hear the pump 'beavering' away.. (or rather whining..) but only the hot water radiator in the upstairs bathroom is getting fed with hot water... how is the best way to fix it? (and yes I have tried to get a plumber around in the first place) help (please)?!