Tiny leak on compression fitting, simple plumbing problem.

Q

Quandary

Well-Known Member
Joined
20 Mar 2008
Messages
8,214
Location
Argyll
Visit site
My saga of Isotherm calorifier problems continue. I now have one issue left, anyone got any ideas.
The calorifier is back in the boat with a new gasket and no leaks from the tank itself, BUT-------
The hot water outlet has a very slow drip, about one drop every 15 seconds when the system is fully pressurized, it stops when the taps are run to reduce the pressure a bit . The 15 mm stainless steel outlet pipe emerges from the tank insulation and the brass temperature mixer is connected to it with a copper compression ring on the very short pipe stub. The compression nut has been screwed up to the end of the thread on the body of the mixer where it can go no further. The pipe stub is too short to be cut to allow a new compression ring to be fitted. It is such a simple problem but looks as if it will cost me a new calorifier, (I have the boat up for sale and intend not to land a new owner with any latent defects)
Before I order a new calorifier, is there any way that this leak could be permanently cured? tape around the ring, sealant or something else? I know that this sounds like a bodge, but there is absolutely no draw left on the compression nut, the leak is so small but large enough to make a damp patch in the locker. Reducing the system pressure would also solve it but a new owner might expect to use the shower. Or could I grind or file a bit off the threaded nut to allow it to tighten up a bit further, tricky when the nut is trapped on the pipe stub.
If I was not selling I would put up with it, by turning the pump off after every use and keeping the ice cream carton under the drip but fancy trying to justify that to a potential purchaser.
 
Try Fernox LS-X Leak Sealant. Circa £5 or so from the likes of Screwfix.

It's approved for freshwater systems and can fix minor leaks without having to disassemble the fittings.

It's a tube of Silicone type stuff that's t sets VERY quickly. I've used numerous times on annoying leaks from hot water systems and it's worked a treat.

Be careful to put the cap back on the tube straight away when using it, as it sets in seconds.
 
Last edited:
Quandary said:
My saga of Isotherm calorifier problems continue. I now have one issue left, anyone got any ideas.
The calorifier is back in the boat with a new gasket and no leaks from the tank itself, BUT-------
The hot water outlet has a very slow drip, about one drop every 15 seconds when the system is fully pressurized, it stops when the taps are run to reduce the pressure a bit . The 15 mm stainless steel outlet pipe emerges from the tank insulation and the brass temperature mixer is connected to it with a copper compression ring on the very short pipe stub. The compression nut has been screwed up to the end of the thread on the body of the mixer where it can go no further. The pipe stub is too short to be cut to allow a new compression ring to be fitted. It is such a simple problem but looks as if it will cost me a new calorifier, (I have the boat up for sale and intend not to land a new owner with any latent defects)
Before I order a new calorifier, is there any way that this leak could be permanently cured? tape around the ring, sealant or something else? I know that this sounds like a bodge, but there is absolutely no draw left on the compression nut, the leak is so small but large enough to make a damp patch in the locker. Reducing the system pressure would also solve it but a new owner might expect to use the shower. Or could I grind or file a bit off the threaded nut to allow it to tighten up a bit further, tricky when the nut is trapped on the pipe stub.
If I was not selling I would put up with it, by turning the pump off after every use and keeping the ice cream carton under the drip but fancy trying to justify that to a potential purchaser.
Click to expand...
Either of your solutions would work, PTFE or file a bit off the nut to give you some more draw. So, PTFE first.
S
 
sealant between the compression ring ( I assume thats what I would call an olive) and where it seats onto the connection on the mixer would be my attempt at a solution. allow it to cure before re-pressurising the system

some might suggest a couple of turns of ptfe tape around the olive.
 
PTFE would certainly be my first port of call - and as many turns as you can achieve up to about 10. However, if the olive is now 'too small' then PTFE may not build up enough to seal it. If that is the case then the tried and tested plumbers method of hemp and boss-white would be the answer. Provides a good thickness of material to seal the gap and still fairly cheap.
 
David2452 said:
Here's what I would do, take the olive off using an olive puller and replace with a new soft copper olive and shallow compression nut,
Click to expand...

The ideal solution .... but the OP probably does not have an olive puller ........ and lives a long way from the nearest Toolstation

and provided the pipe on the calorifier has not been badly distorted.
 
Last edited:
Rather than PTFE tape, if you're prepared to break and re-make the connection, wipe the pipe and olive with a bit of kitchen towel, smear it with a generous dollop of Fernox LS-X and tighten it up again. Give it a few minutes to "set and recharge the system. Job done without straining anything and "first time". If you need to break the system, the Fernox will rub off the pipe and olive with your fingers, you can clear it away from the inside of the fitting with a bit of kitchen towel wrapped round a screwdriver. Re-make the joint with fresh Fernox. I know it's frowned upon but I use it on my gas system as well, just clean it off the outside of the fitting before calling in the Gas engineer for a certificate.
 
Olives can be removed without using an olive puller. Gently compress the olive using pliers, and work round until the olive is loose. Don't crush the pipe.
 
huldah said:
Olives can be removed without using an olive puller. Gently compress the olive using pliers, and work round until the olive is loose. Don't crush the pipe.
Click to expand...

There's a good chance its already crushed. If so what Topcat 47 says may be the best way forward or tape.
 
Last edited:
As said, the joint has been severely overtightened and the only answer is a new olive assuming the pipe hasn't been distorted. If it has then the pipe must be replaced. Is the outlet pipe welded to the calorifier body? If so then get a new pipe welded on. If not then it must be a replaceable fitting.
 
I know it has been overtightened, every time it dripped I did another quarter turn. I think I will try the Fernox and tape as a last resort. I can do it in situ by rotating the casing. If it has to come out again it will go straight in the skip, I am cheesed off with trying to keep this thing from wetting my dusty bilge cavities. If it was a well designed quality made product it would be worth persevering but I reckon a new British made Surecal at not much more than half the price in good old fashioned copper will be a sensible replacement in the long term. The gasket on the Isotherm are now well over twenty quid and the longest one has lasted is three years, some have gone in less than two, when they go the spray soaks the electrics which are in the same casing, tripping until the plug is pulled.

My sincere thanks to all who took the trouble to try to help me.
 
I've used all he suggestions in the past.
The Fernox LS-X Leak Sealant has been by far the best. you need to get it on the olive to outlet fitting surface to give it the best chance. Slap it on the back edge of the olive as well before tightening the nut.
 
You must log in or register to reply here.

Other threads that may be of interest

K
Persistent hatch leak
Replies
7
Views
212
KevinV
K
O
One for the plumbers
Replies
9
Views
372
Overandunder
O

Share this page

Top