Copper cylinder question.

solder?

Owain

I don't think I could get it hot enough. Do you think it could be done with a blowtorch? I have tried, and failed, to solder other large things in the past.

Forget all of those, they are unlikely to cope with the pressure. (Well, silicone might but you would need to drain down and get the surfaces dry).

The one thing which should work is the two part epoxy putty made for plumbing repairs, I have used it successfully in a similar situation. (cold feed rather than heating coil). It sticks on a wet surface and (provided the leak is small enough) maintains the seal until it sets. Doesn't look pretty, but very easy and permanent.

If the leak is too fast, drain down first.

Same arguments apply for an immersion heater as for a heating coil.

Soldering might be possible if you know what you are doing, but tank and coil would need to be drained, you probably don't have good access, and the solder probably won't penetrate the leak path even with acid flux, but a patch should work, if done properly.

I have some Milliput somewhere - have you ever seen that? Sounds similar.

A decent blowlamp should solder it no bother. The copper isn't very thick.

The problem is likely to be cleaning things properly before soldering. And if simply a crack, would need a plate soldered over it.

Not made for that job, I don't know if it would work on wet surfaces. Just search eBay for "plumber epoxy" and you will find numerous different products. Screwfix doesn't seem to stock any, but any decent hardware store or any plumbers merchant should have something.

Okay, I'll see what I can find. Thanks.

I'm pretty sure it's just leaking out of the tightened flange. Also, the tank is coated in some sort of foam (which makes it hard to be 100% sure about the origin of the leak), which I would probably end up setting light to :-)

However, I do have blowlamp, solder, and flux, so it'll be on standby.

You can't get the coil out without taking the cylinder apart.

Where the two ends of the coil emerge from the cylinder there will be a flange on the inside and a fibre washer and nut on the outside. I had a similar problem with my cylinder, caused by one of the fibre washers perishing. I managed to fix it without draining down by slackening the nut and winding some boss-white impregnated hemp behind it, and then re-tightening it.

If you don't mind draining down, remove the external pipe, and then remove the nut and replace the fibre washer - preferably with a neoprene one. You may need to cut away some of the insulation to get at it.

Thanks. No problem draining down - I'll use a garden hose out of the front door.

Is there a drain c*ck at the bottom of the cylinder? If not, it's not too easy because simply opening a hot tap doesn't drain the cylinder. Also, you'll need to drain the primary circuit before disconnecting the external pipe(s) connected to the coil.

I think it's reasonable to assume that if he's planning on using a hose pipe, he isn't intending to try draining it via a hot tap.

Tim

Yes, there's a drain c*ck in the lowest part of the HW exit pipe that will do nicely. The HW/CH system is already drained, since I've just replaced a couple of radiators downstairs. The cylinder job is something I'm doing "while I'm at it". It's a tiny leak that I've just left a piece of kitchen roll under for now, and that has been enough, but now seems like a good time to fix it.

Oops, I mean the CW inlet pipe. The HW comes out at the top, of course.

If it's brazed or soldered joint, then cleaned up of oxidation and soldered. If it's a mechanical joint it will have to be dismantled, cleaned and fresh jointing material and paste fitted.

Plumbers Mait is good stuff.

In article , Dan S. MacAbre scribeth thus

If its any age I'd suspect that there are other places where it might star to fail or leak. Might be best to bite the bullet and replace it than to patch it....

Yes, it's a mechanical joint. There's a very small dribble coming out of it, and there's a small damp patch on the board underneath it. The annoying thing is, it's going to be hard to clean up the mating surface on the inside through the small gap that will be available when it's undone.

It's about 30 yrs old. It's covered in an insulating layer of foam which is good, I suppose, but which makes it hard to inspect.

I'd be inclined to replace it. IME it's probsbly getting close to the end of it's life and it's easier to do it while the whole system is out of commission and in summer. A new cylinder may have a better heat exchanger than your old one.