Nickfromwales

Erm….🤔. Solar power won’t be man enough to run a heat pump for heating in winter unless it’s a 20+ kWp array with a very good south facing setup. When you need heat, it’s winter, therefore 25% max ( usually a lot less ) PV output. So, in a nutshell, no.

Via a buffer to allow segregated supplies at varying temps?

A decent ventilation void on any sun baked elevation will pay dividends. 25mm of rockwool is not worth the effort. EWI would not compensate fully for solar gains, so factor in mitigation against the most prolific problem causer.

And a bunch more reasons on top. MVHR is whole of house in a reasonably airtight house, or zilch. Flow rates are so low, infiltration ( natural ) often exceeds the design room ACH values, so essentially is just blowing past the MVHR. Retro-fit of MVHR is a complete an utter pig to get right, with a lot of build fabric amendments and also needing a very close eye on detail ( so you couldn't trust most 'general builders' to execute this on your behalf ).

I have my moments......usually 3-6 months apart though

2 boilers is just way overkill. Scrap that idea Ok, does the alpha have a secondary hot return connection, or will they allow you to feed that back into the cold inlet? If you have no option for hot return then your problems can only be managed by reducing pipe size to outlet and getting rid of the huge amount of 22mm supply pipework ( as that is where all of your major dead-leg issues will stem from, not the pipe runs ). Centralise the boiler and manifolds wherever you like, and run a HRC to the furthest most outlets to suit. You can run 22mm feeds to 2x DHW manifolds either ends of house for max flow rates, that would be best case for flow, but they would need to be serviced by an HRC and be worst case for efficiency.

Drill one 50mm hole in from the 3rd boss on the fitting under the branch, then T everything waste wise in, inboard of the beam? At worst you'd be drilling 2x 50mm holes and then going through those 2 holes either side of the boss once per side? If a BCO is involved you will need to demonstrate that you've drilled the beam in accordance with the MI's Check before drilling !

Vent for the kitchen extractor should be 150mm if the fan is anything more than a box standard extractor. Anything less than that will remove very little from the cooking. Why not combine 2x 100mm outlets and split them off a 150 Y branch from the extractor? Use the 3rd with a damper to allow fresh air in during the summer to offset the heat from cooking. Or blank it off. Oh, and MVHR for a single room in this house will be useless. Just stick with extraction.

That’s 415 again. Ask for one with a 32a single blue socket outlet if poss. As it’s short term, get one which just connects to the CU without arsing around

You can fit 2x 25L tanks also. Having one rad on bypass ( no TRV and open lock shield ) will give about 5-7L of additional system volume, and you may get away with that. Hopefully that would be the absolute worst case and if you’re using heating, hopefully a couple of other rads would be at least allowing a trickle through partially closed TRV’s elsewhere on the system. Go for it, but try to keep an eye on the boiler cycling to see how it performs.

You can (expletive deleted) off too

You'll be able to sell a tidy one on again. That other thing needs to be gotten rid of as is, eg less any bastardization etc.

Absolute total and utter garbage for designs and system principles. I wouldn't EVER go to them for a quote for UFH, not even for supply only. They made a proper mess of a £2m build and it cost a fortune trying to retrospectively delete all of their errors in a nearly completed project. They didn't even know what kit they'd installed on site, and the plans the client had been issued for M&E reference were toilet paper. Wunda or any others!

Seriously ?!? Do NOT even THINK of running different phases in a caravan off that red outlet. Lethal advice, unless you go to a new 3ph CU with all RCBO's. Cheaper to buy a proper 1ph genny. Leave it well alone and sell off this boat anchor. 👎

Ok, lol, so my 2 penneth is to Foxtrot the castellated panels right off and do as the angry cup ninja above suggests and use clip rails. You want that void full of screed and not part full of worthless air anyhoo, as the screed is your heat emitter. Oh, and all this nonsense about air lifting and whatnot.........time for more tonic / less Gin "NEXT PATIENT PLEASE !!"