SteamyTea

Or cover over with a waterproof membrane.

Right, I have seen what you mean, have you thought of a GRP roof? It is more 'walk on' than any other coating/covering.

Shall hold on to it then, may be more next time I am passing.

I have a full bladder, can I help out?

Good explanation. Water is also 'the universal solvent'. I have often wondered what lubrucants are in normal heat pumps. Must be pretty robust as fridges can last decades.

Can see why they use it, nothing is scary about it, like Goldilocks. Water does have a latent heat of 2257 though

Pretty good. I keep meaning to look (relearn) the formula for working it all out for different gasses, and then wonder why we don't use water as the refrigerant. It has such good figures for fusion and vaporisation compared to almost everything else.

What temperature does it heat your cylinder (using this as a catchall term) to?

Has anyone running a heat pump, close to the maximum to get a higher water temperature, actually checked to see if the built in immersion heater is kicking in?

A £118m developement of 493 flats. So that will be a mean price of £239,351

Spotted another one (I really need to get out) PHE = Plate Heat Exchanger PHE = Public Health England Bet you can't

At what price? My replacement cylinder (after 32 years) cost £220, and I got 50 quid off the pikey when I scrapped it. Unlike the 30 kg of 316 stainless steel I took to him, got nothing.

Is that an easy thing to check out? Seems you are pretty pleased with yours. Yes. You can also get a combined vented.

Does it need an expansion vessel? Agree that UVC are useful for limited flow showers. But probably not cheaper than vented and a 100 quid pump.

I think even water at 97°C can do some damage. Even at 70°C it can kill you.

Or i may not, this time.

This problem can be tackled another way: looking at components needed. So a simple vented system has a cylinder, an immersion heater (or 2), a feed and expansion tank, a ballcock valve, couple of isolator valves. What does a unvented system have?

But it didn't. I think they may make them out of a plastic that has a deformation temperature higher than 100°C now. Old galvanised tanks did not have this problem,

All these 'safety' features add cost and complexity to a system. Mine has a pipe out the top, that then goes into the cold F&E, which can then overflow to the outside. Now these have failed, and killed people (was a case down here a few years back). I think fitting the thermal fuse to the heating element was a good move, means people need to check out what really went wrong (though re-settable ones are a bad idea). No one commented on my ECOCENT (but find a cheaper version) solution. I know the newer ones can take heat from outside now, so one down side of them has gone.

No

Just noticed a new abbreviation creeping in: TS = Toolstation TS = Thermal Store. Not that anyone really knows what a thermal store is.

@J1mbo made a comment about HPs and simple vented systems with pumped showers. Would link to it, but can't seem to do if from my phone.

Do not put it outside I should have been a bit clearer for the OCD/Asperger people. When I say outside, build an 'insulated shed'. Then plumb in as normal. This is a thread about getting cheap DHW, not the ultimate installation.

Rather a lot, I use about 30 litre of water at 38°C My 200lt can supply enough for 2 baths and 2 showers, I just turn the temp up to 60°C+

I use a very basic 200lt vented cylinder with two immersion heaters. The E7 at the bottom and the booster one from the top. Simple pipework, one up to the feed and expansion tank in the loft, one down from there to the bottom of the cylinder, and another off the top of it for hot water (which also has the expansion/safety pipe that runs up to above the F&E tank. I fitted a simple electric twin impeller shower pump that needed a pipe from the F&E for the cold side. Simple, very cheap, reliable and once I had insulated the airing cupboard, not mush in the way of thermal losses. You can get this kind of combined cylinder and heat pump. https://www.earthsaveproducts.com/products/ecocent But look on Alibaba as the units are bought in from China. There is also a Sunamp if space is very tight. Or even an inline electric water heater, as you have no gas. You say space is tight, do you have space outside?