JohnMo

I would Push the floor insulation to 200mm And increase the screed to 100mm in fibre reinforced concrete. Would also have UFH across the whole ground floor, on a single zone (multiple loops). Downside - Your single edge block, would need to increase in height. Then do the whole floor prior to the walls going up.

Does that actually really happen often, or just in peoples heads. I can remember in the 90s, we would feel our uninsulated dinky cylinder and if it wasn't hot, flick on the immersion and have a cup of tea then go for a shower. Expectation has moved on in people's heads, but most people's reality is a combi boiler doing around 8 to 10L/min if they are lucky in winter. Or an invented cylinder doing not much more or less.

Or just a compromise on space which could be inside or if pushed outside. Then just use an UVC. But the mini store is just a small thermal store with a big surface area coil. RED did very similar with a special design from Harlequin was just bigger, but had no G3 requirements.

No - do your own calcs, then you know what you are looking at

Just looked at the attached drawings, I have to agree. You need a lot of mitigating measures to stop your blood boiling from the solar gain (low western sun direct into all those west facing windows), let alone the night light issue.

So minimum humidity monthly average (May) was 52% then in June average starts to increases to 60%.

I would be wary of going that direction, you can get answers you don't want to hear. Curtains, automatic blinds that come down as light intensity hits xx lux. Give them what they may want to hear.

There may also be a min hertz setting, as well as the noise setting. On my ASHP it derates everything down a %.

I saw it on a heat geek video about heating DHW cylinder efficiently. They tell you most of the setting in Vaillant speak.

You may as well use the immersion

You can change that setting, think there are three settings you can use

Black out curtains. Doesn't mean you have to close them. Or even buy them, so long as they see mitigation. They need a box to tick. Not sure anyone actually checks these planning conditions are implemented, once the planning stage is complete. Prison bars isn't a good look or a great selling point, if you try to sell.

Must say look quite close, but I did correct all assumptions made and all standard details and it dropped considerably at revision 2. But take from this is a ballpark of closer to 3kW, not 8kW and nowhere near 12kW. Looking at the spreadsheet the fabric loss isn't too bad, the ventilation losses are stupid high for MVHR.

Someone dropped a ball there. I would 1 Add a small supplement electrical panel heater. Get one with a thermostat so it only heats when needed, £100 and will take longer to collect than install 2 Reduce WC to suit all other rooms, so all rooms run below the thermostat set point (up setting on thermostat to just above target room temp). This will leave the heat pump to run itself. Comment: Would suspect with most the house bouncing off thermostats the heat pump short cycles or has a buffer, either will affect efficiency The uplift in efficiency will probably pay for the electric panel heater. Dropping flow temp from 45 to 35 will save 0.5kW of input electric on its own. Less ASHP cycling will save also, how much? Using a flow temp of 35 would reduce the output of the UFH by 50% (ish) leaving a short fall of about 8-900W, so a 1 to 2kW heater, depending if they switch off during night and it has to recover the heat in the morning

To need 210mm pipes your house must be huge? Use a directional terminal on the wall, these have the inlet and outlet pipes next to each other. Zero separation required. Use coanda supply nozzles, these can be situated anywhere in a room near the ceiling and air follows the ceiling for quite a few meters before coming down. So assuming you have the unit in the landing cupboard and ensuite ceiling is flat. Bed 3 duct would go over ensuite and out of the wall, bed 2 could have the supply nozzle above the door.

I deliberately went completely the opposite way, our original drawings had flat ceiling had the architect change to vaulted. Every room feels roomy and airy, would not go your direction. What is the motivation? Seems a lot of work to possibly store stuff, you will not use or see until you move house.

Spelling issue

My heat pump explicitly does not defrost during DHW production - it can't be the only one. My worry would be another condition of the heat pump, is if it doesn't hit DHW target before it gets 60, it cuts back DHW target 10 degs, each time. Plus - It looks like they have only tested on a Vaillant ASHP.

Also go on renewable heating hub, tat where the book comes from

That sounds about right our lounge is near to 1/3 our total heat loss. Do they run on a timer, on/off thermostat or on all the time? Do they have thick carpet? Have increased the flow rate in those loops to give more energy out. Run those loop 50% higher, so you get a lower dT (differential temperature). Then move the curve back down to lower flow temp. I have never been above 35 and we have UFH at 300mm centres. What does that mean? Heat loss isn't affected by height, just the external areas. Halls aren't normally designed for 21, and normally rob or borrow heat from every room attached to it.

Just had a look at my SAP report, "as built" and looked at the "target emission rate", which is bog standard building regs, no MVHR, double glazed, min insulation, air tightness of 7. The target build adds around 35% to the as built house. That had a heat loss rate of about 4kW. We are 195m² single storey long thin building and lots of glass. Worst design for heat efficiency. So your 12kW is about 4x oversized for well insulated 3g glass MVHR etc - walk away from that quote.

I agree with everything above. We have a sort of plant room, but also stuff elsewhere. I never heard of plant rooms before this build, and really convinced they make much sense Ours Consumer unit, cat5 distribution and battery diverter box in hall cupboard by front door UFH and hot and cold water manifolds in utility cupboard. 2x MVHR units, one in another hall cupboard Second MVHR, old gas boiler and UVC, one PV inverter and battery in roof loft space (inside insulation envelope) MVHR expansion vessel and a few other bits in an insulated shed, that houses the borehole pump filters and second PV invertery.

Your structural requirement comes first then bigger if required for services. So get them designed, not a random guess.

You can pick up an UVC for £1k incl VAT. Doubt they would need 12k ASHP, something very wrong if they need that. I would if buying again just go Panasonic monobloc R32, they seem easy to tune and run well out the box just about silent - they are around £2.5 to £3k. May cost a little more than £5k, but you will have a heat pump of the correct size instead of some monster. UFH on 200mm centres, on ground floor and upstairs wet rooms (100mm centres). Provide provision for fan coils later if you want them for cooling, run at same temp as UFH. You need two zones at least, so use electrical towel rads in bathrooms to do this. Heat pump system simple wins the day, less cost to install, more efficient - no buffers or volumisers, no manifold pumps or mixers, no actuators or zone valves, just a diverter. If you end up at around 6kW and the pipe runs are short you only need 22mm or if you really want 28mm piping.

Electric towel rads, I would fit those anyway. Do as many on here have done Do your calcs first Buy and install the heat pump yourself. Forget to mention in first post Our living room is 6m tall, has one wall is all glass, all other room circa 3 to 3.5m all with 5m² of glass except wet rooms.