JohnMo

They are part of efficiency measures brought in about 10 years ago. 93% isn't really that good. There are much better out there, 93% eff is the minimum allowed I believe.

The main I would question should you have DHW within the cylinder? Or a small body of heating system water? The issue may be legionella if you have the body DHW floating on heating temperature via WC. This could be at the least ideal temp for period of time. For it to work all year you need it to heated in the summer also. So you really need 3 way valve and thermostat, if you intend taking any heat from the heat pump. Then the volume you are taking will mean short cycling if not managed well with a 8 to 10kW heat pump. Also don't assume all flue come out through the wall, mine is in the roof for example.

Not really seeing anything different from the link provided to that drawn above. Except the expansion tank is very small. Although similar to my previous link, this is smaller could be positioned where a combi boiler came from (900x400mm), on a simple shelf. It has a heating coil, and everything after that is customisation friendly, maybe even get a bigger coil if you asked and if there enough space for it. https://newarkcylinders.co.uk/product/newark-indirect-combination-cylinder/

Some comments in bold above

Stubbled across this MCS cylinder sizing guide Domestic_HW_cyl_selection_guide.pdf

You need room by room for radiator sizing, but you are good enough with the whole house calculation to get the total heat KW required. Jeremy spreadsheet in boffins corner is quite accurate. Show a slight over demand above 5 degs, but below pretty good.

Is this one they inverted earlier - but round. Available in direct and indirect. Filling controlled by ballcock. https://www.screwfix.com/p/rm-cylinders-indirect-vented-combination-cylinder-85ltr-900-x-450mm/58056?tc=TA5&ds_rl=1249404&gclid=Cj0KCQjwz8emBhDrARIsANNJjS5MEl-8asvGrJRypWI7b_-_BttGe55t0lnawxdP2fAMuuTmHtrhWFgaAgM3EALw_wcB&gclsrc=aw.ds

So was mine. The next house had 120L uninsulated vented cylinder and that was in a four bed house, that was fine also, didn't know any different then. If we ran out of water, the immersion was flicked on for 1/2 hour.

Alpha boilers make/made such an animal, but for preheat to a gas boiler. Alpha Flowsmart 25 and 50. Designed to go in the heating circuit and has a DHW coil.

Looks like the cylinder has been sold and the seller hasn't bothered to take the advert down

I found it it a pain to use, have tried a couple of times then deleted it.

The Willis site is an interesting read, and the whole concept of heating water. You want a shower in half you flick the switch, willis heater add heat from the top down and you heat just water in the cylinder. We seem ok with with dumping 1.5kWh into the house in heat loss every day of the year to have a hot cylinder 24-7 on demand. Would suspect, the Willis heater used as designed would be very economical to run.

Good spot

Just found this, slightly inconsistent data. But makes a bit more sense. 1.8m2 for the 200L.

Not really closer what I'm hearing other than a bird. Is it before after or during the fan starting/stopping/running

When wet, the next day it's satin

Rye oils - ceder oil also called decking oil. Goes on easy, goes a long way, mine is still red 2.5 summers later; after only a single coat. Also very cheap, compared to other named brands

Also make sure your choice can regenerate the carbon filters

Ignore all the rules you have mentioned. With MVHR you don't really need anything, but if you are cooking smelly food the carbon filter helps. Concentrate on looks, but importantly noise. We rarely use the fan above the first setting, because it make little or difference and is noisy.

Look in UFH section a couple of recent threads on this subject.

No sure it is, the inverter, battery, PV and mains all connect into the gateway. The gateway manages it, think only it and the Tesla battery are certified to operate like that. Connects like this,

Pretty dinky coil size

They were my thoughts also. Plus if I was away, not sure the wife would know what to do to repressurise the heating system. All are reason not get unnecessary agro. You take a very small hit in CoP, for an easy life. I would also doubt the plumber that comes along to service would have a refractometer. Would like be supposed when someone confirms there was checked. However the degradation mechanism is generally oxidation and exposure to high temperature, non of which should be present in an ASHP system, which is low temperature and a closed pressurised system.

Spotted a Daikin heat pump cylinder - 200L for a very good price. Model EKSWHU200B3V3 Does anyone know the coil size? Or any issues driving from a 6kW (max temp 60 deg from heat pump).

Thanks for that will discuss with the electrician. He said he has installed the Givenergy all in one before and is a registered installer, but I am the first to ask for a gateway. So he is off to do the online training course.