Glow-worm flexicom expansion vessel pipe connector nut leaks

[zeroid]

Replaced this expansion vessel today, but couldn't stop the connector leaking (EV was supplied with two fibre washers, I tried one first then both). I did not tighten the nut much at all initially, but that's what I resorted to in the end and have now damaged the pipe.

I've got a replacement EV pipe coming Tuesday, but what's the trick with these so I don't mess up that one too? I suspect its to do with making sure the mating face is exactly aligned with the threaded part on the EV as the nut is tightened / may have been some corrosion or muck on the old pipe/nut that made it difficult to fit right.

 

[Madrab]

TBH you shouldn't really be in there unless you have the right equipment to ensure that everything is working correctly and the boiler is firing properly, once the room sealed case is re-attached.

As far as the pipe is concerned then everything needs to be clean, corrosion free and lined up correctly. Shouldn't need tightened up too much. Is it a proper Glowworm part you are using and are the seals the correct size.

 

[Agile]

What pressure did you put into the replacement EV ?

Was the old one really failed?

 

[aptsys]

You shouldn't need to be cranking too hard. I assume it was not cross threaded and the mating edges are relatively flat?

 

[dilalio]

Fibre washers go in your mouth 5 mins before you fit them... So that they start to swell up and make the seal once in place.

 

[zeroid]

You shouldn't need to be cranking too hard. I assume it was not cross threaded and the mating edges are relatively flat?

Yes, definitely wasn't cross threaded, I was screwing the nut on easily with my hand. I think the mating edges just weren't perfectly aligned as I tightened the nut more.

What pressure did you put into the replacement EV ?
Was the old one really failed?

Old one was spurting water from the schrader valve when pressed. There was still loads of water in it sloshing around on what should be the air side when I removed it.

New one came pre-charged to 1.5 bar which I checked.

 

[Agile]

Sounds pretty bad.

But sometimes if you drain all the water from the air side and then recharge they will last a bit longer.

A good test is to depressurise water side and see if they will hold the air without leaking too much.

If boiler is to run at 1.5 bar cold I find a little less air pressure works better.

 

[zeroid]

Thanks but the one you see in the picture is the replacement so no worries there. Just didn't plan on needing a new EV pipe too.

The old one was so bad I had to re-pressurise the system every day the heating had been on, until I figured out to empty one of the rads by half as a temporary "expansion vessel". I've just been waiting till I didn't need the heating to get the job done.

 

[Agile]

I have often use a rad as a temporary EXV.

Usually after the user has done this "English" thing of bleeding all the rads before the winter thus depriving their system of anywhere to expand to when the EXV has never been checked and repressurised!