JohnMo

To give a quick example, flowing at 55 at -2 compared to day 35 at -2 would use around 40% extra electric. System design is the be all and end all of heat pump efficiency. It's super easy to accept a rubbish system then have an uncomfortable house, that's too expensive to heat.

Seemed to do fine, didn't seem to have any shortage of hot water. Hot water heater takes about 40 mins at the end of it the condenser is frosty.

No stored volume of domestic water is below the need for G3. It's a buffer cylinder really with a DHW coil, not really a thermal store. Exactly as I listed in the image above. Defrosts could be a issue, but my heat pump specifically doesn't defrost, during DHW - it's not allowed by the manufacturer control logic.

That would work, I would use around 50mm as a minimum. Insulation on pipes 25mm.

Is there a reason you have to go via the council? And not direct to installer and they would claim the grant via normal channels.

Just watched the follow up video. Looks good, seems to work well. It is as shown in my post above. The heat pump heats the store directly and DHW is taken via a coil. The blending valve would be installed if you store water above 60 degs.

Ignore heat pump size for now. The system design flow temp needs to be as low as practical. At the end if the day you are the client, not the government or anyone else. The government is funding YOU via an approved supplier installer. I would be pushing for a max flow temp of 35 to 40 @ -3. Anything else is just asking for high running cost. Other suppliers out there. Just tell them NO to current design. Tell them to fix it or you will find another supplier.

If architect will not or can't explain why, find an architect who you can work with. The architect should be able to produce a U value and interstitial condensation report quite easily, to show you the issues (if there are any). Another option is full fill poly beads, which give a self draining cavity

Tech specs look good. You may be surprised by the price, but sure in a good or bad way. Looking at the specs, they quote the U value for the glazing unit only, not the window. So depending on frame that figure could be better or worse. I would choose your frame, then tell them to quote with the vacuum glazing. All companies buy in glazing units. Or get a quote direct yourself https://fineo-vacuum-glazing.co.uk/new-vig-technology-for-older-properties/?gad_source=1&gclid=CjwKCAjwmrqzBhAoEiwAXVpgopshC3r1JHPktll0X4iUmu7osYDF58q_w4fDppojtzb4AGXkxC9xCxoCggkQAvD_BwE Another alternative is krypton filled which is better than argon filled.

A man in a digger way easier. A day or so all done, the digger would pull everything out the ground at the same time.

Bigger plug? So it's a tight fit.

That would work. Good thinking.

A similar concept been about for years (since 2018 ish) - funny it for a gas combi boiler. Just swop the combi boiler for a heat pump with a bigger coil and delete the blending valve and go direct to taps (not to the combi). Same 4 connection. Neither a vented or invented DHW cylinder, just allows for additional volume with an additional or increased heating expansion vessel

Bingo - not The 35mm refers to the depth of the box, the issue is the 35mm box is good for up to 16mm wall thickness you are wanting nearer to 25mm (with plaster), so then you need the deeper 47mm back box, but not all of them are suitable either

Must be being treated as heating system volume, so must be full of central heating water, so the volume of main fed water is limited, contained in a coil or PHE as with a thermal store.

Good point. I have seen schemes where DHW is delivered via a PHE, such as a thermal store. The HG solution is really just adding a buffer to the system to allow the ASHP to ramp up. Mine would take a good 5 to 10 minutes. So it could be a coil in a coil HE within a buffer tank. The outer coil is in the buffer water the inner coil in the ASHP flow path. So are they just treating the store as a buffer from a plumbing perspective.

I noticed a while ago in my ASHP instructions, there are settings for that type of operation. " In Heating, ASHP always turned towards DHW" 10.2.2 HEATING MODE ON DHW STORAGE TANK If the parameter H130=1, the ASHP exploits the DHW storage tank even for central heating. In these conditions, the outlet of the DHW valve is also enabled during operation in heating mode and not only in sanitary mode. The valve is deactivated during defrosting and in cooling mode. Think you would have to alter the plumbing to allow it to work. A a 3 port valve directs towards CH or cylinder not both.

You to start by making a decision - are you happy with the walls, if not get wall straight and true first. If happy with walls do it as it says start at back corner and work towards the door. Decide your datum wall, back wall would be my choice. Leave a gap all round for expansion, cut boards to wall angles, otherwise looking like a dogs diner comes to mind. Cover gap with skirting or trim pieces.

We struggled in some areas due to the amount of cables, we had 50mm everywhere. Any smaller than 25mm will be splitting as you fix them. 50mm or 11mm isn't going to make the room feel any bigger or smaller

Mgo has an A1 fire rating (non combustible)

The link on page one, do mgo skins - 2 hour fire resistance. https://www.sipsdirect.co.uk/product/mgo-sip100-1-2m-x-2-4m-x-100mm-panel/

Two L shapes 1.5 x 3m.

Glass ballastrade at decent prices and good delivery https://www.made2measure.co.uk/post-and-saddle-system/ Did a quick cost and it's about £1k for glass with posts Because if the fall is more than 600mm it has to comply with building regs. First bullet point in the attached.

Sorry not agreeing - I will bow out and leave you to it.

There is a how it works video in 18 hrs or something. It shows a cross section of the mini store and it's lots of coil inside. I am wondering if its more like a harlequin cylinder.