JohnMo

Dot and dab, will not stop leakage, so unless you seal the block work, 4 ach may be as good as you will get. It could be worse. We have Durisol ICF, which is made of woodcrete, which leaks like a sieve. I did a parge coat, with sand cement and lime. On an airtest prior covering with plasterboard, we had leaks in window corners and at dpc. The walls themselves had no leaks.

Not sure why you say that, as it is officially allowed. https://www.gov.scot/publications/fire-and-smoke-alarms-in-scottish-homes/

The battery ones have to be sealed so you cannot replace the battery to comply. Once battery expires you need to install a new smoke or heat detector.

Became a requirement for rental properties about 10 years ago (I believe). You to have a heat detector (only heat not combine heat/smoke) in kitchen, plus smoke elsewhere.. Google combined ones are mentioned in the guidance notes, as not to be used, as they do no comply with the registrations, being combined smoke and heat.

Somewhat lost me. First point, yes Second point, you didn't ask for that, you asked for the furthest point for secondary return with manifold. If you want it at all outlets, that could be done. The flow will go through the manifold so that is also heated. So all outlets close to manifold get hot water quickly. No a secondary return does not save any energy, as you are pumping hot water around a circuit and it will loose heat constantly, hence a need to insulate well. It save running cold water down the waste while you wait for the hot water to arrive. I have mine on a timer so it only runs when I am most likely to want it, to save energy.

We are in the country, it quite contemporary, but the planners words - fitted in with the vernacular.

We are in Moray, we had to have slate roof, but we have wood cladding and stone. And it's single storey. So doesn't have to be ...

Just doing that now, already have 3.1kW of PV. Could do with some water heating in the shoulder months when PV output isn't generating at full capacity.

B&Q?

I take you still have to get a warrant? During the warrant stage I change quite a lot including the whole build method, quite a few sizes etc. Could stone slips be an alternative to render, from a distance you get the same look, but close up a very different look?

No issue that's what I did. Take the return pipe to the furthest outlet, pump (suitable for potable water), check valve, and back to cylinder.

Why not look at a different company, or eBay and get the local plumber / electrician to install? May not get the grants if you buy on eBay, but could leave money in pocket now for other things.

Way too many lights, you'll need your sun glasses on before you go to bed. We have 4x shallow 80mm spots, a central pendant and 5A sockets by the bedroom

Similar to above, 200mm PIR, an additional polythene layer, UFH pipes, but 100mm concrete floor. We did the complete floor, insulation, UFH and top 100mm prior to walls. Found it easier that way.

Report worth a read on ventilation performance. Atamate_SDAR+Paper+2019+(1).pdf

I forgot about the slamming doors now you mention it.

I used Outsourced Energy for all my UFH had no issues. My bits came to about £900 for 190m2. (Excluding auto balancing actuators) A 2 port valve can be bought from anywhere, I bought one from Screwfix. Get Salus auto balancing actuators, make commissioning easy. Would expect a plumber for a couple of days, should be the cost to install.

Supporting guidance is a good place to look https://www.google.co.uk/url?sa=t&source=web&rct=j&url=https://www.gov.scot/binaries/content/documents/govscot/publications/advice-and-guidance/2017/11/building-standards-domestic-ventilation-supporting-guidance/documents/building-standards-domestic-ventilation-supporting-guidance-version-2.1-november-2017/building-standards-domestic-ventilation-supporting-guidance-version-2.1-november-2017/govscot%3Adocument/Building%2Bstandards%2Bdomestic%2Bventilation%2Bguidance%252C%2BNovember%2B2017.pdf&ved=2ahUKEwi157bV26_1AhWFiVwKHYYyA_gQFnoECAkQAQ&usg=AOvVaw15vStB1by3VrENg1Nc3XWy

MEV and dMEV are not allowed according to building regs if tighter than 3m3/m2. So balanced supply and extract with or without heat recovery is the only option left.

And all that ProDave just said.

If your air tightness is less than 3ACH then in Scotland you have no option. But great to live with, you put a toilet/ bathroom light on and silence, 3 month on I still still like it. A well designed system is the best part silent and in the background.

Efficiency is all to do with area and how much electricity is generated from that area. A 100% efficiency panel (if they existed) is just smaller.

I bought mine in a pre first lockdown sale, so my cost isn't real world cost, plus it came with all the roof integrated bits. Their site still has the various packages on, so worth a look.

We have washable carbon filters as well as the grease filters

That does not fill me with confidence