JohnMo

Simple answer is yes. You need to target how you design, how you purchase, make little or no change during the build. We got green larch direct from the mill for about 1/3 russwood prices. Generally keep things simple, UFH in screed is cheap and easy. Do you need multiple zones no. Spend on insulation , airtightness and quality of finish. Design of house really makes very little difference to build cost, efficiency of design and how you build it is where cost savings come from. Choose a build method that is cost effective.

Think all industry is the same in the UK now, we have become a culture that changes black boxes, with little or no thought - computer say... they do and don't look much further.

It was just ready to plasterboard, all insulation, vapour and airtightness done, but with access to fix stuff. So service void battens on walls and ceilings etc. Holes through wall for mvhr were blanked off at the wall.

I have WiFi in the summer house which about 25m away. I use the plugs you stick in at both ends, one end connected to router. Seems to work just fine. People will say it needs to be on the same circuit, but mine goes through 3 consumer units and still works fine.

Not really re inventing, just a variation, like spoked becoming alloy wheels. Does the same thing packaging slightly different.

All rooms are vaulted. Vapour and airtightness layer then 50mm service void and plasterboard, taped.

Sorry you may need to expand, not sure what you are asking?

They do several sizes

More to the point do you need or is it a good idea at all. It provides zero movement tolerance, which isn't good. For context My frame is sat at indoor ground level, we have oak flooring glued to screed, there is only 45mm of frame showing at the bottom.

Or if you're considering a combi boiler, fit a system boiler instead and a HG small cylinder where you could, way better performance than a combi, hot water to the tap as quick as an UVC cylinder, indefinite hot water, just set heating system as PDHW.

Thermal bridge wide looks good. Upstand, can be PIR to save money and get as good or better performance. Don't like the angle steel on glass

We kept it simple No BT or openreach to the house, although I did lay a cable to outside the house and the nearest pole (in same trench as power) just in case it gets better than snails pace. We just got a 4G router and a cat5 or 6 cable to each room, two to office and two to living room. Not sure why they need internet, but I am sure someone will come up with a good reason. But while you are digging things up may be useful in the garage. CCTV is all wireless. Yes.

Think that's the advantage of the smaller cylinder, as with the smaller volume and height you are able to to get to decent flow temperature and replenish quite quickly. My 210L slim line, completely destratifies as soon as the reheat cycle starts. I think it's more about making heat pump accessable and installable for combi replacement. Think the practically and consequences are different. This HG cylinder is in a closed system with a given volume of water spread across the whole house. It's at a pressure of around 1 bar gauge. The cylinder has an open end so any expansion can more outwards to the rest of the heating system which would act as heat sink. An UVC has a blocked discharge i.e. taps are closed, it has check valve in the inlet. It cannot allow expanding water anywhere to go.

Really depends on spec PEX based UFH pipe isn't UV stable, however pert-al-pert is. So just depends on the pipe you've used. If it's underground it should be ok, not so sure how frost tolerant it is however.

In the short term it should be ok, but over time and as rusting increase it could start cracking in the concrete. Corroded Steel takes up 6x the volume of not corroded Steel. Laser is the way to go. I would say no, you are not supposed to back fill foundations. There's info in building regs on what is allowed and not allowed. As this will also be an inspection point for building control. Get it right know the facts.

We have an allowance each, I spend it whatever projects/tools I want she spends it on clothes etc. I don't bother what she spends her money on, she doesn't care what I spend my money on. Works well.

Solar thermal is a water based system and it requires a coil to transfer the heat to the cylinder water. However a solar PV system is an electric system, so provides main voltage electric. The only practical way to get heat into the cylinder is via the immersion heater with PV. So the diverter goes between the your consumer unit and the immersion isolation switch. With a CT clamp on the tails to electric meter, when it detects outward electric flow (export) it switches on power to the immersion. So if you are exporting 1kW it diverts 1kW to the immersion.

Correct. The volume of water in the cylinder of the HG arrangement is treated as part of the heating system with expansion and relief provided at the heat pump end. As long as the return leg from this cylinder is always in the flow path to the heat pump all is good. But if your heating system volume is 100L, and expansion sized for that, you would have to increase the expansion vessel so it's sized for 150L and the appropriate upper temperature limit of the cylinder.

I would look at 90mm also. Found it worked out way cheaper, as all runs became single ducts, for our house which is long and thin. With 75mm most would have ended double 75mm ducts to each terminal.

You don't need to get down to that detail, just get pressure drop data from the chosen manufacturer and they will list pressure drops for duct and fittings. You just need to do the most onerous route for a semi flex manifold system, you then add the plenum and the duct between MVHR and plenum to get the complete pressure drop. Get that as low as practical.

You need to work out how the air will move around the house, so if air enters room A, B and C, where does it travel to get to the extract terminals, you are aiming to have air wash through the whole house. Plenty of good practical advice in the attached. 2018 MVHR Good Practice Guide rev 1.1.pdf

So I get notifications start by typing"@" then the user name from the drop down that appears. You only need a single coil. I use a cool energy diverter, this has a timer that allows to time immersion running or you can just leave it in diverter mode. So your plumber is talking rubbish, a double coil is for solar thermal, not for PV diversion. Above all else get a heat pump cylinder with as big coil as you can get, with X plan (or Priority demand hot water).

Seems a bit of a strange way to do duct runs. Looks way too many ducts. That's not right, you need to calculate duct length and pressure drop. Your kitchen needs extract, but your living area is very likely going to need supply. Use this to help decide the room flow rates required.

No issues doing that as far as I know. Everything I have seen on the MCS heat loss calcs they are over egged generally.

Correct, the superflow temporal store required an additional 5 lt expansion if system volume exceeded x lt.