Cistern condensation

Bilbo44

Thanks, I didn't realise I'd already mentioned it. I've been firing-off posts at a few forums.

No, I don't plan on a sales concession, I'm just hoping to find a UK equivalent but I wouldn't expect a WRAS difficulty. I notice a reference here to a "blending valve", so I'll try to locate one of those. I think it's strange that two major plumbers' merchants haven't heard of anything that would solve this particular condensation problem, given that it's such a common problem.

Bilbo44

This may be the answer, from diydoctor.org.uk

You can get an "anti-sweat valve" from applegate dot co dot uk. There may be other suppliers, but that's the first one I've found.

You just take a feed off a hot-water pipe, to take the chill off the cold-feed into the cistern, and the problem should be fixed. It looks as if it's adjustable, and should be an easier answer than trying to attach insulation either inside or outside the cistern.

I'm still amazed that so many plumbers, and plumbers' merchants, had no idea there might be such a product on the market.

keystone

Bilbo44 wrote: »

Thanks, I didn't realise I'd already mentioned it. I've been firing-off posts at a few forums.

No worries.

No, I don't plan on a sales concession, I'm just hoping to find a UK equivalent but I wouldn't expect a WRAS difficulty

What I'm saying is that the yankee product might not be.

I notice a reference here to a "blending valve", so I'll try to locate one of those. I think it's strange that two major plumbers' merchants haven't heard of anything that would solve this particular condensation problem, given that it's such a common problem.

Yes that was me HERE. If by two major plumbers merchants you mean chains I'm not surprised considering the level of muppetry thay tend to employ behind the counter, in some cases (:D), allegedly (:D:D).

Cheers

keystone

Bilbo44 wrote: »

You just take a feed off a hot-water pipe

Yep - also on the other thread.

BTW my toilet cistern is fed direct from mains and it never gets condensation, I don't have a blending valve, nor is it plumbed into the hot water supply. I don't have a problem with condensation at any time of the year. What I also don't have is a totally hermetically sealed house. Perhaps there's a clue there.

Cheers

Bilbo44

You may have a point there, although I see you're in Surrey and we're a few hundred miles to the north (on the same latitiude as Moscow) so it may be that your mains-water comes out of the ground a bit warmer than ours.

The suggestion of applying a coat of yacht-varnish came from a plumber working in B & Q but, if that stuff comes in the volume that would cover a yacht, you'd maybe have to buy a lot more than you need.

Then, of course, you could offer to go round painting other people's problem cisterns!

Cheers!

Bilbo44

Our plumber was reluctant to use one of those blending valves, because he'd not seen one before and was concerned about avoiding cold (or hot) water feed-back into the hot (or cold) pipe.

So, our solution to warm-air condensing on the cold surface of the toilet-cistern, and soaking the floor, has been to install 'double-check valves', a.k.a. 'non-return valves', along with gate-valves on both the hot and cold supply pipes, joined at a tee-piece into the pipe heading for the cistern. Total cost (materials and labour): £55.00

It was easily done here because those pipes were already travelling along the wall of the garage, just through the wall from the toilet, so we only needed an extra piece of copper pipe about a foot long (300mm).

Once installed, it was a matter of adjusting the relative flow of water, i.e. reducing the amount of hot water (by turning the valve) until the condensation returned, and then increasing it a bit to take enough of the chill off the water going in to the cistern. As the outside temperature drops, as it may well do this month, we can increase the hot or decrease the cold. In spring, the hot water can be turned off.

I'd still prefer to use an insulated cistern, but never found one.

john-306

Just how long is the hot water going to stay hot? This weather I'll give it 20 mins and you'll have a cistern full of cold water again

ListysDad

Thing is John it'd go from hot to ambient so no temp gradient for condensation to form...

Mikeyorks

The real thing to avoid ...... is a wife ...... who takes a bath with the bathroom door virtually shut. Increases the humidity significantly and the cistern pours.

I could shower all day - and the cistern is bone dry. Admittedly the high pressure in line extractor is directly above the cubicle and the bath steam does have to wander around a bit to get to it. But - get rid of the wife and you get rid of the drips.

Bit surprised no one has mentioned the condensation on the rising main as it heads to the loft! Warming that up with a blender valve is a tad more difficult

Bilbo44

ListysDad wrote: »

Thing is John it'd go from hot to ambient so no temp gradient for condensation to form...

That's it exactly. You only need to mix in just enough from the hot water supply to take the chill off the cold water that normally fills the cistern. As long as the surface of the cistern isn't significantly colder than the room-temperature, condensation won't form there.

I've just been checking the rising main, at the stop-!!!! under the stairs. It's cold, but no condensation there at the moment, and the pipe's insulated.