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cbushnell · Joined: 22 Mar 2008 Posts: 7 Location: Hampshire

Hi All,
my father and I fitted a replacement indirect hot water cylinder today, re-using the existing plumbing, with new compression fittings to the cylinder. Unfortunately, once filled, it leaked from the actual cylinder at the central heating feed. We assumed that this was a fault and the shop exchanged it, but the second one has done the same and in addition, leaked from the flange on the tank at the cold water feed.

It could be faulty of course, but I'm concerned that maybe the plumbing is ever so slightly out of line, which could be putting stress on the cylinder at the feeds, once the cylinder is full and therefore so much heavier.

Do you think that we have caused these cylinders to fail? should we have replaced all plumbing to the cylinder?
Thanks,
Clive

thescruff · Moderator Joined: 03 May 2003 Posts: 4249 Location: Bath

Could be faulty if you haven't damaged anything.

Are you plumbers or diyers

cbushnell · Joined: 22 Mar 2008 Posts: 7 Location: Hampshire

We're diyers. we were very careful to use two spanners when tightening the fittings to the feeds as the seem to move very easily, especially the hot feed. I guess that's the weight of the coil inside as it even moved on it's own when you move the tank around.

As I said, we were very careful, but with the second one leaking, you start to question yourself.

thescruff · Moderator Joined: 03 May 2003 Posts: 4249 Location: Bath

The back nuts on the coil should alwas be checked because the can become loose in transit.

Another point to watch for is that the coil doesn't turn when you make the fittings on

Can you post a pic showing where the problem is

cbushnell · Joined: 22 Mar 2008 Posts: 7 Location: Hampshire

Ok,
how would you check the back nuts - throught the imersion hole (seems a long way to reach)? Here are pics of the leak area (tank is drained again, so no water in pic I'm afraid.

http://www.flickr.com/photos/24422698@N04/sets/72157604208547712/

straker1966 · Joined: 06 Jan 2008 Posts: 164 Location: cambridge

was there any stress on the joint on the tank when you made the fitting?

ie was the pipe lifting the tank up when it was empty? all the weight of water in the cylinder pulling down on the pipe would cause that backnut to leak. it looks like the pipe is a fraction too high and its pulling the coil connection askew.

drain the cylinder, undo that backnut quarter of an inch, wind p.t.f.e tape round until it is almost flush with the edge of the backnut and then retighten.... easy peasy Wink

thescruff · Moderator Joined: 03 May 2003 Posts: 4249 Location: Bath

I would just empty the cylingder and pinch the nut up to see what difference it makes fitst

You can see the back nut in your photo, where the pipe comes through the copper, you dont need to get inside.

Just had a thought you said you used two spanners, is that the nut you put a spanner on when making the fittings up

cbushnell · Joined: 22 Mar 2008 Posts: 7 Location: Hampshire

Hi Straker and Tscruff,
thanks very much for your help with this. Scruff, the back nut was the nut put the other spanner on when tightening the fitting to the feed pipe. I can see now that it would have done no good as without actually tightening the backnut at the same time, it could come loose once the fitting bit on the feed pipe.

Will try tightening the backnut first.

thescruff · Moderator Joined: 03 May 2003 Posts: 4249 Location: Bath

Exactly, if you use a spanner on the backnut you will loosen it when you make the fitting on

straker1966 · Joined: 06 Jan 2008 Posts: 164 Location: cambridge

the cyl stat is too high as well....should be 1/3 way up from bottom...

yes i know i should get out more.... Embarassed

cbushnell · Joined: 22 Mar 2008 Posts: 7 Location: Hampshire

Scruff and Straker,

Thank you both So much for your advice! We backed off the back nut on the hot feed and wrapped quite a lot (should have been a bit more) ptfe behind it. It weeped very slowly after we filled the cylinder, but it was so slow we decided to run the system and see how it looked when the tank was hot. It's now stopped leaking all together - hurrah! I expect that it will soon get a nice seal of calcium in the inside, so should never leak again.

Hot showers all round after 2 days without HW.

As regards that thermostat - we'll move it down a bit. Does having the stat to high mean that the water in the bottom of the tank doesn't get properly heated?

thescruff · Moderator Joined: 03 May 2003 Posts: 4249 Location: Bath

Leave the stat where it is Shocked

I always put mine in the top 1/3rd, and to this day I cannot see the reason for putting a stat which is supposed to control the hot water, in the coldest section of the cylinder. Confused

cbushnell · Joined: 22 Mar 2008 Posts: 7 Location: Hampshire

I like that advice - no more to do for a while then.

Thanks again Scruff! Do you think we've been unlucky with these cylinders or is it not that unusual to have to improve the sealing on the feeds?

thescruff · Moderator Joined: 03 May 2003 Posts: 4249 Location: Bath

cbushnell · Joined: 22 Mar 2008 Posts: 7 Location: Hampshire

Yeah I expect you're right. God save us from well meaning amateurs.
We're very grateful from your help.

Best regards,

Clive