Compression fittings, how tight?

bootneck · 7 Dec 2006

Ive just fitted a mira excell unit into a wall using the standard compression fittings as suppied with the unit onto hep20 hipe(and inserts) all went ok, no leaks after flushing etc for an hour of two so I cemented in the pipes.

About 3 hours later I noticed both the hot and cold glands had small drips forming below them so i nipped them up slightly which seemed to increas the leak.

I took the glands apart and looked inside, all nice and clean etc and the olive seemed to be seated as far as it would go.

I put the glands back together and tightened the glands fairly tight, but Im affraid of over-tightening them in case I do harm.

What am i doing wrong?

Cheers.

paul

ChrisR · 7 Dec 2006

Expecting plumbing to be simple

Wind some ptfe tape round the olives, then when you do up you'll feel the tape squashing - a 4 inch spanner is enough for me to do them up tight enough.

bootneck · 7 Dec 2006

cheers I'll give it a go.

seriously hate plumbing, it alwas feels like waiting for a bomb to go off !

ChrisR · 7 Dec 2006

Sometimes it does go off, then I hate it too.

bootneck · 7 Dec 2006

if you tighten the nut too tight will it do any damage ?

(sorry im a biff with plumbing!)

Onetap · 7 Dec 2006

bootneck said:
if you tighten the nut too tight will it do any damage ?

(sorry im a biff with plumbing!)

Of course you are, you're a bootie.

Shouldn't do, unless you manage to strip the threads on the fitting. It'll swage the olive immovably onto the pipe; overtightening doesn't achieve anything and it's bad drills. Don't try to take the olives off again. Hand tight and then 1/4 turn with the wrenches is usually plenty.

You some times get brass olives in fittings which can be as hard as steel. I think they sometimes save 0.1p on cheap olives. I prefer the copper ones You don't need the PTFE tape, but the olives work-harden and you sometimes can't get them to reseal if you've undone the joint. PTFE paste on the olive will get a seal; something like the Virgin White stuff here.
http://www.bes.ltd.uk/nav_graf/frames_cat.htm? Your plumbers' merchants will have something similar

And take the roll mats off your arms. And take the dress off.

bootneck · 7 Dec 2006

you seem to know a lot about plumbing and even a little about the corps

Thanks for the heads up, its still leaking after nipping it up a few times now, maybe I'll try the ptfe and Ive got some paste somewhere, what can i be doing wrong though i always seem to struggle with compression joints?

(boss white the stuff ive got, is that what I need to use ??)

sime10 · 7 Dec 2006

If you struggle with compression joint's GIVE UP

bootneck · 7 Dec 2006

if i could afford a plumbers rates believe me I would, but hey thanks for the advice.

sime10 · 7 Dec 2006

you could try push fit, just make sure you cut it proper

Blasphemous · 7 Dec 2006

Try Fernox LS-X. Just follow the instructions on the tube. Should get it sorted.

But Sime's suggestion of Push Fit will almost definitely sort you out.

ChrisR · 8 Dec 2006

Some of the plastic pipe mfrs recommend ptfe tap on the olive. Hep was one. The reason is obvious really, you won't get the force on the olive to metal joint when the pipe isn't resisting the movement of the olive as much. That means you don't get in to the elastic range of the metal. Using copper doesn't help in that respect, it's less elastic than brass.

tsunami · 8 Dec 2006

genuine conex gear is the stuff to go for. hardly ever had problems with the rings; but that is what does the sealing. plenty of times i chuck the copper/crap rings away and put conex in they have the alloy content right. as they used to say on the boxes the best joint in town. but try telling my tight boss . we use the bes italian stuff/ junk.

ChrisR · 8 Dec 2006

Agree 100% theirs are best, though I think it's the shape/hardness more than the alloy. Even they will leak on plastic if done up by a gorilla because the (any) olive will distort so much.
Even the junk compression fittings seem to be ok with a turn of gas tape, though some of the olives are a joke.

Pity Wickes don't sell cheap Conex bags any more

bootneck · 8 Dec 2006

i think i worked out what was going on.... the pipe wasnt sitting square in the joint so consequently the olive was not seated correctly, if that makes sense?

On speakign to hep20 tech support they said they would always advise on using ptfe when joining compression to copper, not boss white etc as the substance might corrode the plastic.

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Compression fittings, how tight?

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