Iceverge

0.8kW would be plenty for our house if it was continuous. Have you any evacuated tubes to tie onto it for the lower winter temps?

Do you adjust you panel angle for the lower winter sun?

Looks nice. Very LA hills. I double down on the overheating cautions and also the heating energy requirements for all that glazing. Good windows are still 5 times worse than average walls in terms of heat loss.

It's highly unlightly the slab is structural. The load from the above flat and the roof will be transmitted to the ground by the walls extending right through to the foundations. What is the existing floor? You speak of a screed. In all probability it's a concrete floor. Probably about 100mm thick. Insulation is plenty strong enough to take distributed loads. You can put a whole house on it in the case of an insulated raft foundation. However it doesn't like point loads, think high heals. If you had only one layer the risk is that at the joint the OSB/PLYWOOD wouldn't be able to distribute the load sufficiently and would sink into the insulation making a wonky floor.

I'm thinking ecotherm did the U value calcs and passed them onto your designer. They are hallucinations unfortunately. Start at 200mm PIR (or 300mm EPS)in the floor. 200mm mineral wool in a full fill cavity and 3g good quality UPVC windows and doors. Avoid french doors and brush sealed sliders. They leak like the Titanic. Instead make sure all doors and windows have compression seals to shut.

Dig out the floor. It's a day or two of work. Add 200mm PIR or 300mm EPS, screed or power floated concrete floor. You can use the opportunity to run wiring in conduit to all the outlets and avoid pulling down ceilings. Otherwise. PIR as much as you can. 9 or 11mm OSB in two layers floating over the top, joints crossed, screwed and glued. Cork tiles or carpet.

Any link to be fix. I had something similar last year with ours (proair 600) but I put it down to a tilt in the unit and not being able to drain properly. Must have another look again to see if it's ok.

Depends on the windows I would have thought. They may need pre drilling if there is metal reinforcement in the frame. She could always use windows straps but if she doesn't want to then something like this maybe.

I assume this is a renovation? What kind of heat loss figured do you have for the remainder of the house? UFH pipes widely spaced in 150mm concrete and heat pumps may not be the best choice as it's very slow to react and only works as a "banked heat" in very well insulated houses. If you have a poorly insulated house a quick reaction system would be preferable. IE very large radiators or high output (closely spaced pipes) UFH in a thin screed.

The nub of the issue here seems to be the limited power transfer capacity of the UFH at low flow temps. I imagine due to the dry install with a very thin insulating layer of air around the pipes and the insulative effect of the OSB and timber floor. The system would probably work pukka with a gas boiler. It's a done deal now as I guess you're not going to bother pulling up the floor an a simple resistive rad is so reliable and cheap to buy. However from a design perspective to maximize the heat transfer power of any UFH system my thoughts would be. 1. Maximise the surface area of the pipes. Longer pipe runs with lower diameter. 2. Higher conductivity pipes. 3. Attaching the pipes to mesh as @TerryE did. Perhaps even using an extra roll of chicken mesh or similar to distribute the heat as quickly as possible. 4. Using a very low viscosity screed to maximise contact area with the pipes when pouring. 5. A dark covered a rougher textured surface to loose heat to the room as quickly as possible. EG slate tiles. 6. A screed with maximum thermal conductivity like anhydrous screed rather than concrete. This is of course separate to the energy storage side of a heated slab.

Have you considered covered GRP grating? Used some for our thresholds. F Just cast it into the concrete inside and support outside with some "muck" or a few blocks. Leave it with a slight fall towards the outside drop the door on top with a bead of sealant and hey presto it's done. If you fill the pockets with foam it performs well too.

excellent. any chance of some thermal pics/back of the hand observations?

Yup SketchUp, it's an old version on my PC. I would think a big coil is important but I'm not an expert. There is something to be said for buying as close to a standard product as possible future replacement etc.

I think this is what you mean? Telfords Biggest Cylinder (400l/500l) doesn't fit The larger cylinder even with the lower cradle would be fantastically tight if you did want any insulation above it. Their Standard 300l and below will be fine, even with the PIR below the rafters. You may need the immersion relocated/lower cradle as it will be a pain to remove otherwise. No need to stop at 50mm insulation on the underside of the rafters then either.

I would say it's worth getting a quote from a supply and fit company. It was comparable when we built ours. PIR between rafters isn't a recipe for success.

Use insulated plasterboard over the 2x4 in that case. As thick as you can get away with.

I would get some prices to make an informed decision. In 2020 in Ireland we had a borehole all done and dusted for about €4000. Similarly our council requires separate supplies for a farms and houses. A person in my locality was only granted planning on this condition although he owned an existing borehole 30m from the house. As to whether the second borehole got done in the end I couldn't possibly say but it was shown in the plans....

It looks fine. (Also metric tape. Nice.) What is the height of the highest part inside the studs and I can redraw it accurately? Are you planning on lining the ceiling with more insulation or is that it and I can edit my drawings as applicable.

Flow issues can be overcome with a cold water accumulator and a booster pump.

Might internal shutters be an option?

That's an excellent COP. For a small project if one wanted a heat pump without a heated slab or DHW an A2A HP would be a simpler proposal I guess.

I would use... Hardy cladding Battons Breather membrane 25mm marine ply 2 x 4 framing with 100mm Rockwool full fill between ( much easier than PIR to fit) and you still have a very good Uvalue. 100mm of PIR over the framing. Tape all joints for airtightness. 70*20mm battens over the top of the PIR. Plasterboard and skim. U value about 0.145

Could you add secondary glazing instead?

Not massively. It's full of louvres and would just let the sound through. Are internal shutters an option? Good roller shutters have tounge and groove joints and the slide inside brushed guard rails. They also have some internal foam so your contractor is right on this one.

Floor paint look smart. Do you have any issues with rainwater blowing into the garage?