Immersion tank leak I can’t fix

[Chapster]

Hi everyone. I need some help please.

After removing and reinstalling my immersion tank to do some work near it, I have a leak I can’t seem to fix.

The heating coil connections have sealed again perfectly, but the DHW out top connection has a little bubble of liquid appearing over time and doesn’t respond to tightening or a few wraps of PTFE around the olive, and the cold water in at the bottom of the tank is leaking the most, creating a little puddle over a few hours.

The cold water connection has a brass union/reducer that screws into the tank and accepts a 22mm pipe with olive. The 22mm olive joint is fine, it’s the reducer/tank joint that leaks.

I removed the union, cleaned off remnants of gunk and PTFE tape, cleaned all threads, wrapped it in PTFE and reinstalled. No improvement at all.

Removed again, wrapped more thickly with PTFE tape, put a bit of plumbers mait around the edge and reinstalled. Still leaking the same.

No obvious splits in the tank connection point or reducer. I’m baffled.

I’ve always managed to seal threaded connectors effectively using PTFE tape so I’m lost now.

All advice welcome.

 

[Scally-Ho]

Being old school, I much prefer hemp with jointing compound (Boss White) for threaded joints, of which I've never had a threaded joint leak. Before stripping it all down and starting again, check each brazed boss to make sure a small part of the brazing has not sprung a leak.

 

[denso13]

I removed the union, cleaned off remnants of gunk and PTFE tape, cleaned all threads, wrapped it in PTFE and reinstalled. No improvement at all.

Needs quite a bit of PTFE on the threads and make sure of the obvious, that is is fully tight into the cylinder.

 

[Gasguru]

Hemp was banned decades ago on potable water connections. Try Loctite 55 string instead of tape.

 

[Madrab]

Other option is Gas PTFE, it's thicker and can allow for a more secure joint IME.

 

[Johntheo5]

I've never had any problems using PTFE tape with a smear of Uniwhite, a jar of which I've had for ever, apparently never goes hard, it certainly doesn't, in the jar at any rate.

 

[Chapster]

Hemp was banned decades ago on potable water connections. Try Loctite 55 string instead of tape.

Thanks for the suggestion; I’d never heard of Loctite 55. Bought some, followed the instructions from their website, and I now have a dry fitting.

Wasn’t as tight as I expected screwing it in, but I imagine I could add a few more loops if that’s needed (like an outside tap).

Amazing stuff. I can see why reviews usually include a statement that they’ll never use PTFE tape again.

I’ve since read several comments around the interwebs in which plumbers say they were told that PTFE was never intended to seal on its own, that it’s a solid lubricant used to prevent galling, and a sealant like boss white should be used with PTFE tape.

The slight bubble of water that kept forming at the top outlet no matter how much I tightened the olive or added PTFE around the olive was resolved following guidance from a post on here which I’d seen earlier while searching before posting. It appealed as it mentioned Hylomar Blue which I have for working on engines. Smear of that around the olive, several wraps of PTFE, another smear of Hylomar and tighten. Dry as a bone now.

Thanks everyone, this forum is a great resource.

 

[Johntheo5]

You should try STAG sometime and you will really find it galling if you ever try and remove it.