Nickfromwales

The hot water expands into a manufacturer supplied expansion vessel. Your current system does the same via the vent pipe over the CWS. Typically they operate around 3-3.5bar, as dictated by the control group / multiblock. Link That's a combination valve that provides 5-6bar cold mains PRV, a PRedV, a balanced 22mm cold draw off point ( to supply all mixer outlets with balanced hot and cold pressure ) and a, sometimes, a tapping to connect the EV. ( Fyi the EV goes on the uninterrupted side of the cold mains inlet to the cylinder ). Again, that's usually manufacturer supplied with the UVC ( they come with everything needed to complete the installation, less isolation valve ).

Cold mains water is forced into the very bottom of the UVC and pushes the hot water up and out of the hot outlet at the very top of the UVC. The heat source for the UVC is typically a 'wet' central heating water fed coil ( indirect ) which sits in the cold water and that heats the water up. The hot water from the heat source, and the water that comes out of your taps, never meet . An UVC which is fed electrically, only, is referred to as 'direct'.

To stop this UVC thread drifting any further I've started this one.... Anything other than choosing / fitting an UVC can go there . I'll see about moving the content accordingly.

A bit like asking someone if they have a burglar alarm, and my favourite reply .... "no, we haven't been burgled yet".

Yup. That's where I got lost Jeremy!

Ok. In that case, you may be better off with a TS. I do forget ?. Good job you didn't 'rush' out and buy an UVC . With oil and UFH, there is quite a big conflict as the boiler can't modulate. That is usually best dealt with by means of a buffer tank but a TS would be the buffer AND provide DHW it's just down to losses and how the house is occupied. With a TS, you'd typically need it heated according to space heating and DHW consumption, much as with an UVC or your current hot cylinder, but the norm is for it to stay hot pretty much all of the time if the house is occupied other than with 9-5'ers. A TS will ebb heat away much quicker than an UVC, mostly due to the extra connective pipework etc, so is less likely to retain useable DHW through the day unless the time clock is left on constant. The summer is where the TS may fall largely redundant ( as you don't have PV so this info is case specific to you ) so there is an argument for a smallish buffer + UVC vs TS. You keeping the upstairs rads and going all UFH downstairs? An open pipe 'combination' TS won't need G3, but a sealed and pressurised one will. As usual, no easy solution other than the one that suits you best .

You've got oil haven't you?

View a TS as an instant water heater, like an extremely powerful combi. .

Off point, but have you already plumbed to go with manifolds? I can't think of any reason to install manifolds in such a small house TBH, and there is a saving to be had by just buying 15mm Hepworth and unifying the install. Just have a 22mm 'rail' off the UVC, after the TMV, and take all the 15mm runs off that. Fit regular ballofix Tap isolators ( £1 each ) for primary isolation and your good to go at a fraction of the cost. Am I right in assuming your mates aren't G3 so that's the bit that's missing? Fwiw, my mate let his lapse whilst going through a divorce and I ended up using one of Telfords registered ( accredited ) installers to inspect and 'sign off' the UVC. Cost me around £150 iirc, so to answer one of your questions, I, a non-registered regular Joe, fitted that from start to finish and had it signed off via a 3rd party. Admittedly I have fitted a good few of these under supervision and beyond so I know the 'does and dont's' so all you need to do is ask. . I can bounce your postcode on to Roger @ Telford and see who is 'local' to you as TBH your going to need to have someone who can do the annual inspection anyhoo.? Do you have anyone G3 near you? Yell.com maybe?

Thread tidied up ( to focus on the topic ). Nick.

Very simple folks :- If in any doubt, ring your insurance company and ask them ! They are devious b4stsards so best to clarify any specific criteria they may have 'indirectly imposed'.

?? @ProDave, copy your last over to there and we'll carry on accordingly ? @ me so I get a ping .

Hi and welcome. Good to see the SAPV's are starting to become a bit more popular. . Do you have a plumbing schematic yet?

Some small units rely on the DHW pipework for the expansion. Itll be in the installation manuals, but if rebranded Chinese crap from b & q then its Russian roulette.

I always run these in copper TBH. It's not the type of pipe you want letting you down. Read the G3 docs as for a D2 run over 3m you need 28mm and a max run of 12m total iirc. Bends are 1/2m again iirc. You need D1 to drop at least 400mm vertically to the tundish and D2 needs to drop at least 400mm vertically after the tundish before any invert, but the more the better TBH. Go 28mm as soon as possible. whats the length of the run?

That would need sufficient pressure at the upstand. Any chance of getting a reading? Late evening is best when the local network is under less demand. If one person has teed off the upstand, does anyone actually care as long as it's not getting abused? If they were watering the garden all day then that's one thing, but an occasional hand wash or 5 min shower isn't going to have anyone in tears is it? How many people share the upstand?

What's the crack with the upstand? Is it just a communal,'outside tap' ?

After the CU it simply becomes 'fixed equipment'. Ideally it should have local DP isolation ( 20a DP switch to the side ) for disconnection. Edit : Maybe an din mounted 80a isolator would tick that box?

What water system / plumbing do you have so far? You've got a wash hand basin and kitchen sink, they plumbed in already? Do you have attic / high up space for a coffin tank ( storage tank with fitted lid etc ). ?

Say what? You been licking great crested newts again ? ?

Time to start a thread in one of the relevant topics folks .

Best to mention that for PH levels you certainly want as low a wattage per m2 as possible. 100w is acceptable, 50w would probably suffice TBH, but I'm not sure of the availability at that power rating for the various applications. @Barney12 There are foil type ( nearly completely flat ) versions for under carpet fitting Click on the 'Description' tab here

I've slept a lot since then . Looks a good wire, and that's where the consideration must be as that's buried under your expensive tiles. The controllers are all generic so don't matter a jot TBH. Still, I'd heartily recommend going for the intuitive / smart Warmup stat as it is self-learning so will switch on / off according to warm up and cool off delays / overruns so will save you on energy bills.

Pretty much sums up Build hub quite nicely. . Welcome aboard.

Cheers. Just wondering if you'd get revenue from export after your own consumption if you weren't fitting via MCS.