JohnMo

If anything like the UK, an approved install and the price you quote would be approved. Export prices without a smart meter is circa 4p and with a smart meter tariff closer to 15p. The reason many on here do DIY installation of PV is the cost difference. 10 to 14k to save 1k is 10 to 14 years payback. Looking at your spreadsheet, it seems there are some errors Have you made allowance for rainy and cloudy days? Allowed for angle of the panel and sun? i.e. used the link I provide to give a more accurate reality. In May you aren't going to get 29.7kWh every day, maybe not any day, no cloud, no shade, and a tracking system maybe, but a fix array very unlikely.

Do you get a feed in tariff (FIT) still. Or that the rate for export with an approved system? So savings are one thing, cost to install another. What sort of cost would the install be?

13.4kWh battery. PV is around 7kWp, but at different angles and plenty of shadow from trees. So really more like a 4kWp system.

We are 200m², currently cooling with ASHP, with solar and battery, we are not paid for any export and ALL electric is costing about 30 to 40p a day. Heat pump efficiency is all about design, the simpler the better. You run 24/7, you have one heating zone, no buffers are needed, no thermostats are needed if run on Weather compensation. A CoP of 4.5 and above is pretty easy to achieve, including DHW heating. The ideal design is, ASHP, 3 port diverter, UFH manifold (no actuators, mixer or pump) UFH loops and a cylinder, interconnected pipes insulated. Cylinder (3m² coil)£1k or less, heat pump shop around £1500 upwards, UFH several hundred pounds.

If you can install a boiler and ASHP is easy.

No it won't, you want opening windows to enable purge ventilation to get rid of excess summer heat

A little detailing and thinking through any cold bridging, you can exactly the same thermal performance. Both can be thermal bridge free. Locals you know and trust is half the battle. But do not expect them to understand thermal bridging, airtightness etc, you may have to drip feed them. You don't need to comprise with either system and it doesn't have to cost more than a rubbish design, think, plan, think a bit more, tell your architect exactly how you want drawn. Be an active client, that reviews and has final sign off, on all aspects of the design. I was the final approved on all the architects drawings.

These are quite straightforward, but you will need to think about cold bridges where you meet the SIPs Really need PIR or EPS, 200mm for PIR and 300mm for EPS ideally, little less is ok if not going UFH. UFH is pretty cheap to install, we have it at 300mm centres, think @TerryE is similar. I use an ASHP, so I can get cooling, @TerryE uses a time of use tariff and a pair of Willis heaters. Don't under estimate how little heat moves about in a bungalow, MVHR flow rates are low and don't help distribute. A heater matrix in the mvhr will help with heating (not cooling), at Passivhaus MVHR flow rates it will distribute 10W/m2 floor area - no more than that. I would get a decent boiler with good modulation. UFH helps with boiler over sizing as the floor will buffer the heat. Last year with boiler with min turn down of 7-8kW, I was able to heat house with little or no overshoot and without boiler stopping once started. A +0/-0.1 thermostat is your friend and so is thick screed (100mm plus) as it will buffer heat freely. What ever you do you need to consider weather compensation for UFH or radiators or opentherm for radiators, this will give low flow temperatures and limit any likelihood of overshoot of room temps, plus its way cheaper to install than multiple thermostats. Don't do Y or S plan, do X or W plan (or Priority Domestic Hot Water), so you get one flow temp for cylinder heating and another for CH. This will get efficiency from boiler. For me this makes an ASHP a no brainer, shoulder season all heating is just about free.

Make life simpler use the link to work it all out fir you. Big array unless you get paid to export and or have a battery - lots of energy will go to waste. https://pvgis.com/en

Correct sarking boards, from memory 22mm x 150mm

Through flow, use a coanda extract terminal. It's also open plan to kitchen, or is the white line a wall with no doors?

I would delete the extract form bed 2 & 3 storage, there is no need. They cause air to short circuit. Pantry should be an extract Master bedroom supply move to near wardrobe, but do not uncut bedroom door. This gives better cross flow across room. You don't really need the dining supply, move the kitchen extract to the white line between kitchen and dining area. Or better for routing may be on the kitchen side of the pantry wall

First if Daikin hold the MCS licence the design has to be installed per your layout at the start of this thread. If the plumber was the MCS licence holder and issued the certificate, they are the designer, not Daikin, Daikin sketch is just that a sketch not a drawing. So you need to get your head around that side of things. Running multiple circulation pumps kills CoP, often the second pump is driven from an unmetered (not metered by ASHP) supply. So secondary side circulation is missing from CoP. Example I just changed my pump in the ASHP from running all the time (manufacturer default) to intermittent as demanded from temp controller and cop increased by 1 to nearly 5 for the last week. I only have a single pump, imagine deleting multiple pumps. Your design as given by Daikin, was sound, zero issues. Don't fret about heat pump size, you can run an oversized heat pump with very little impact on CoP, as long as you cycle rate is is ok (especially with UFH), 2 or 3 cycles per hour in mild weather is ok. Run the system in weather compensation without thermostats, should yield a SCoP over 4 easily. Convert buffer to volumiser or delete and get rid of the additional pumps. You have the design, find a plumber to change it for you.

Just make sure you seal everything (ventilation gaps etc) really well with stainless steel mesh to keep rodents and wasps out. Wasps will find the smallest gap.

Insulated your shed or garage Box in you cylinder to reduce heat loss. If you have loft, insulate more, cut in to strips just small enough to get through loft hatch, then using cut line, foam the pieces back together again.

Could imagine coming to a pool of water, and a new picture on the wall. And then getting the blame for it. Who's stupid idea was to put heating in the wall.

Quite a few are, some of the ones above me in the chart are still doing heating - in England, many aren't doing DHW lol.

Sorry I was thinking more Scotland and the mandatory use of sarking boards for increased wind loads. Bit different from fencing - but not much. Mine in the process of being installed. Gaps are used to traverse the roof and are back filled when finished.

After the minor change to circulation pump settings and leaving a week to settle in, thought I would check the heat pump monitor SCoP leader board to see how my system looked compared to others. So currently sitting 9th overall based on 7 days of figures Mine is Maxa i32V5.

Has the above assumed you leave all your blinds up and just let your room flood with heat. If so that's a flaw in the maths. Also taking some basic things, if your windows are facing south and have no shading, the solar gain doesn't start until you get sun through the window, so late morning onwards. Your peak load is at 9am. So would say your windows are facing east, is that correct? At 9am even on a hot day, it's still cool outside, so open the windows and doors have a blow through, as day starts to get warmer than inside close everything up. Let your cooling, whatever you choose do what it does. AI is great but you need to add a dose of common sense, or you are down a rabbit hole, shite in, yshite out.

We did quite a bit of research before buying our stove. An all metal stove heats up very quickly and output all it's heat to the room. A stove covered in soap stone, takes a while to heat the stove, heat is much more gradual and controllable. But pile it with logs you will melt. We light add a log, turn down the air to minimum and that's about it, if really cold we may add an additional log or two but only when the first log has just about disappeared.

Yep, just like below, centre is DHW heating, the blue sections either side are cooling. As soon as there is a DHW call the heat pump swops duty from cool to heat, the diverter valve moves to direct hot water to the cylinder, once complete it all reverts to cooling again.

Some ASHP do not support cooling at all, some require a few bell and whistles (cost adders), other do it out the box. To switch between heat or cool is generally a volt free input. I just use an spare light switch, that's it. DHW continues to work as normal in either heat or cooling mode.

Dew point is nothing complicated, people would have you believe there is, for some reason. House at 22 the dew point is around 12 degs. Keep above that the dew point issue isn't there. You don't need to lag pipes any more than you do for heating. I would do A2A or A2W not both. Both can do heat and cool. Make you choice and move forward. You could look at Panasonic squares loop system also. Things I like with UFH No noise, everything is hidden, silent. One switch to go from heat to cool. Thing I didn't like with A2A, drafts, but liked the coolness in the house. But got to a point where we switched the Aircon off and just slept with windows open (34 degs and 100% humidity) because the drafts just bugged us and made us feel dry.

Up to you really. I didn't even think about cooling until after the first year in the house. So my floor is designed around 18W/m². Floor surface is a property of flow temperature, pipe spacing, insulation below UFH and depth from surface. My floor runs at 18 to 19 depending on solar gain. The more solar I get the harder the ASHP works and cycle time increases from 10 to 12 minutes to a few hours. This brings down mean flow temperature, hence the difference in surface temperature. Surface covering makes a big difference, carpets kill cooling.