JohnMo

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

Everything ProDave says Shop around, prices vary, I got a package with 10 X 310w panels, all the other bits to make the system work from ITS Technologies. Plus get an immersion diverter.

There are 2 phase of cladding, the first phase was completed at beginning of the summer (gable and right of gable) and second phase (left of gable) about two weeks ago. Will be using Osmo UV protection, so hopefully 6 to 10 year between recoats

Ground slab should be giving you a good u value circa 0.1, get that put down in 2 layers with staggered joints, with all gaps foamed, top layer tapped. It will need a polythene sheet over the PIR and under the UFH pipes. The UFH pipes can be stapled to PIR through the polythene. Wall I try to improve u values if you can. Your new walls could you use thermolite blocks for one of the skins? Also the cavity with Celotex Thermaclass may be better with blown insulation or in Rockwool or similar as it's easier to construct (brickies likely to make to a mess of it). Not a huge fan of dot and dab. I did battons, and dry lined, but if you are plastering on top of plasterboard, why not just plaster the walls, you will get less air leakage overall.