Nickfromwales

Nope. Just leave it for now and do the TMV's after you fit the UVC.

Long pipes & insulation etc is fine. The only thing you need access to is the Temp+PRV, which is tank mounted as it has a temp probe, and the immersion. At 250 / 300 Ltr, you'll be able to select dual 3kw immersions so why not go that route for occasional 'boost'? That'll add another 6kw of heat input which, along with the ashp, should give you shower after shower after shower and still have headroom for a bath. The ashp will quickly start replenishing the heat as it depletes, and a combination of the two, when under duress, should be ample imo IF you go for a 350ltr cylinder. I know that's pushing your Monday to Friday envelope a bit, but you must design for your worst case scenario I'm afraid, and I think this would be the best option. Remember that if you fit the 15mm Steibel after the UVC, it can only service one bathroom. If you connect both rooms to it, you'll be strangling the 22mm hot outlet of the UVC and subjecting it to the max flow rate the instant will allow ( through said 15mm internals ). Very difficult to see how you'd 'provision' for retro fitting the Steibel at a later date as that would require a whole different approach to what should be a straight-forward UVC install ; UVC to manifolds in 22mm pipe. 15mm feeds to each room or outlet. Job done.

I'd also say just fit one and set it as high as you can tolerate at the basin. That'll give plenty for the bath as hands are more tolerant than your 'white bits'.

Spit it out man

I haven't used it for a while so check on some off-cuts first. Or should I say Onoff-cuts?

Basin and kitchen sink?

I can't believe we've done this to him so late in the game He was just about to mix some tile adhesive too. Damnit.

Me too.

Well, I'm a man of my word..... I'll shut my mouth. . For everyone who didn't know, I asked. Bingo.

With a wet coil and an ASHP, and a 300ltr UVC, I seriously doubt if there is any need whatsoever for the instant water heater. Id just mount the cylinder stat lower and have the ashp kick in sooner to deal with higher DHW consumption. 2 or more showers isn't going to deplete that imo, but as your storing at lower temp I'd be tempted to go slightly bigger to give better redundancy, IF you ever see yourself having guests frequently. Forgive my poor brain, but are you having PV?

Ok, I'm still lost. Inside the SunAmpPV's you have a recirculating loop which heats the primary side of a PHE, yes? The EV inside the SAPV is therefore not going to lend itself to the DHW circuit in your property. If I'm right in my assumption above then the previous is incorrect. Or I'm wrong and the primary is sealed and copes on its own with the EV being on the secondary side of the PHE, in which case I'll shut my mouth ? @JSHarris can you clarify, unless @TerryE is in a position to do so?

A picture speaks ( or in this case, saves ) a thousand words. .

Ah, just re-read this and you mean an ALL DC solar arrangement including a DC element. It may be worth looking at a higher kw AC ( primary ) immersion if going that route. Sounds like more complication TBH, so maybe just go AC solar and use the excess to power the fridge freezer or take @SteamyTea's advice and just pay for the electric on demand.

Only problem with the dc route is you'd have to have one or both immersions on a changeover relay so you could 'mains boost' when hot water is being used en-mass. The relay ( contactor ) can be used to switch from dc solar to ac mains accordingly, remembering that solar will be of little or no use for the morning bathing, literally just offsetting the losses would be a good option though. Also remembr that you'll need a legionella purge cycle too so it'll need a time clock on the boost element to do a 1-2 hour heat cycle weekly. Edit : one or both immersions instead of both immersions

Thought so. @TerryE, why do you think you need additional expansion? You'll have a lot of hot pipework for that.

The SAPV EV is for the primary side of their PHE is it not?

Beware of some glues and sprays as not all are for upvc . Some go horribly yellow after being sprayed with the activator so chose well for the finishing / makeup work.

Yup. You could chip a spud through one of those without missing a beat. .

Crossed with J. Maintenance is an issue, "fleas with the dog" and that.

I'd only recommend one to offset the effect of a loo flushing or white goods filling. With your pressure and flow rates I'd leave space for one, and pipework provisioned accordingly, and have a live run for 3 months or so to gauge if you actually need one. Youll need a PRedV anyhoo which should smooth out the spikes ( flush valve closing and 1/4 turn taps being closed abruptly ) but even a small accumulator will significantly improve the delivery characteristics of such a healthy supply, ( and would facilitate having a higher set pressure at the reducer ). Having 30-50 litres of 'buffer' would be a good medium imo, so basically two showers running simultaneously and no noticeable drop in pressure when the aforementioned get used elsewhere in the property. The zimlet ones from PumpsUkLtd are robust and reasonably priced. My gut feeling is you will live without it.

They're a big name in pumps. Very good bits of kit. . Hudson Reed are another.

Just chop into the hot and cold in the attic space. You already have joints under the bath, so you could chop it in under there TBH, but personally I despise the thought of not filling a bath thermostatically as I hate to see a bath overfilled with scalding hot water and then cold water being poured over it to cook it back down ?. I also have heard about little ones accidental getting into the bath before the cold has been added and then getting scalded or even dying from the injuries ?. As I have 4 dependants, I have done what @PeterW is proposing, e.g. a thermostatic 3-way diverted and no taps. The only thing I wil say @Onoff is you'll have better flow rates through your tap and the separate TMV than I have through my mixer, but I absolutely didn't want taps on my bath.

Not just nice to have, but a requirement when your renting to 3rd party . You cant have non thermostatic devices fed from an instant water heater, electric OR combi. You have to cap the upper temp limit somehow with an UVC too, either by setting the temp on the cyl stat to 55/60oC or by fitting a TMV ( set at 50oC ). A secondary TMV ( 46oC ) just for the washbasin is a nice touch, giving excellent comfort, and you'll need to go down the TMV route here imo so you can set a higher storage temp ( to get away with having a smaller cylinder ). Dual or triple immersions are available so you can run one for storage and set the other to come on when the occupants are bathing ( boost ) to speed up recovery when it's needed most.

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