JohnMo

Someone has already opened the tap, not sure what the pump brings to the party at that point. You have a full 3 bar pushing hot water down the pipe. There is only one flow temp out of any heat pump or boiler. Two different flow temperatures is only done by mixing down the hottest flow to the make it colder. Again why would you bother. If you are on UFH and your house is cooling down while the heat pump is DHW you have some issues with insulation that need addressing. Our house is around the same age as yours, our UFH can be for Manny many hours and house temp doesn't change. We also have a whole gable end fully glazed. Will obviously be communicating or it won't do hot water. Check what position the sensor is installed in. Needs to be lowest sensor pocket to enable whole cylinder to be heated

We have just put a sail over our decking area in front of our french doors in the kitchen dinner. Only difference to light, is it stops the sun getting in. Room still bright etc, not hot from the sun. So you may be over thinking it.

I would get some insulation offcuts and box the pipes in to bottom of the wooden backing board, do a few layers of insulation if you need, foam it all together, but not the pipes. Let them do the power floating, then removed the insulation and fill the void with self levelling compound flush to floor.

Can't help with thermal store sizing, but generally bigger rather than smaller. Two types for DHW, one is a coil and the other a plate heat exchanger and pump. Believe the plate heat exchanger yields the most DHW for a given size of cylinder. So plate exchanger will allow a smaller cylinder for same DHW delivered. Other thing to think about is boiler run time, you are best to get a reasonable run time and then a decent gap between runs. So things you need to know, to size cylinder. No of people in the house - DHW sizing. Heat loss calculation for whole house. This will give you a likely time between boiler runs in winter. A note: UFH will draw warm water from cylinder, so if cylinder hot there will be a mixer, it will add a little bit of hot water to return water, and send it around the circulation loop again. Radiators if oversized will do similar. But if small hot radiators these may deplete cylinder quickly to fire up boiler again. So the hotter the heating system the more likely you are to have a big cylinder, this could be wrong?

Will watch with interest - my next project apparently.

Suspect the thermal transfer is actually similar compared to wooden floor glued down with no air pockets. Compared to SPC that is floating and with the underlay. All 4 doors don't have to pass. You only need one accessibility door. So all criteria needs to accessed including what's outside. We also have many doors and all are flush thresholds. But only the front door is the accessibility door for building regs

Best place is read many of the previous threads that ask this very same question. They will guide you through the design process. There are many house designs and quoted costs. An installed system can be any where in the region £6k to 12k even more. We were quoted (192m² single storey) £10k, so did my own for under £2k. Go on to the Paul heat recovery web site also, there is loads of information on there about design, flow rates etc.

Sorry just reread your first post I really would not have UFH on ground floor at all. Do all the major heating upstairs, bedroom needs to be cooler than a living space. Any heat that escapes downwards from upstairs UFH is going to heat downstairs anyway. No idea if you need to cool downstairs if you do, use fan coils to bedrooms. Use the UFH upstairs as heating and cooling - If going heat pump. You need to decide on heat pump or boiler then go from there. Maybe ask for a heat pump quote, it may make the decision for you.

That is the same for ALL heat pumps and boilers that run priority water. That seems a lot reduced to 2? You really need to reduce this time. And reduce pump speed. Time it when you are likely to be in the kitchen only - and actually need hot water, definitely not all the time. We have our down to 2 hrs per day only. The other thing to add is a pipe thermostat, on the return close to the cylinder, as soon as it senses the return temp getting to say 35 (adjust to suit) it switches the secondary pump off. The pump then comes on as the temp drops about 4 degs. If the bottom of the cylinder is always cold, check the position of the cylinder sensor - it should be near the bottom of the cylinder not in the middle.

Have a towel by the door, dry the dog before they come into the house? We always wipe the dogs feet and dry off if wet. The dog now expects it, waiting outside until told to come in. Also have a carpet runner or floor mat that doesn't show to many marks at the door. Then put some proper wooden floor down, that can be glued to the screed, so you get decent heat transfer from your UFH.

Two schools of thought. One insulation and lots of it, 150mm PIR minimum. Or none. Lots of insulation is always best, results in least energy consumption. The or none version - you run the UFH at a low and slow temperature 24/7. The ground below the house buffers heat. To get it to work you need to screed over the pipes so everything transfers heat Well. If you switch the heating off the heat moves away and you start the buffering process again wasting loads of energy. Thin insulated floor, the heat still goes down (slightly slower) but cannot come back, so is not good force energy consumption. You mentioned FCU as an option for ASHP and UFH. UFH alone can do cooling with a cooling enabled heat pump. Or use FCU for heat and cool, without the bother of UFH.

For UFH what are your floors, suspended or direct to ground?

But not if a 3 phase, as per phase will be below 3.68kW, so should be G98, tell them after, I believe?

Option 5 Keep oversized oil boiler, feed to a thermal store, then boiler being oversized doesn't make much difference. Will run happily not cycling. Then take heating system water and DHW from store. DHW via a plate exchanger. Then you can heat big rads at lower temp or UFH if you want. Or leave as is. With ASHP the sensible option is to run low and slow 24/7. On off operations cause the heat pump to at higher loads playing catch up.

But generally only for a MCS certified install, not a self installed system or one where you get your non-MCS certified electrician. So make sure you are fully informed before making any spend decisions

Start by using the correct units then it will all make sense. Panels are sized in Watts. So 10 500W panels is 5000W or 5kW. That is the size of the inverter you need. So a 5kW inverter or smaller. A PV array outputting 5kW for one hour is 5 kWh, for 2 hours is 10kWh. So using kWh in this discussion is a bit meaningless. Except if discussing daily output. PV in summer with no shading can generate for about 10 to 12 hrs, in winter 4 or 5 hrs. Summer output in your location is going to be closer 30+kWh, most of which is generated while you are at work. In winter 2kWh is more likely. I see your lunch time usage is about 2.5kWh, a good summer day a 5kW PV array could be generating 5kW or between 12am and 1pm 5kWh. Great if paid for export, but not so if you are giving it away. Plus what @SteamyTea says.

Be careful with assumptions and PV. Output varies hugely, based on shading, direction, angle, and time of year. Expect almost nothing mid winter. The figures you quote are average figures so a bit meaningless. You size inverter mostly to match it's output, you can overclock also, so move PV kW peak panels than kW rating of the inverter. Various inputs into inverter need to be taken in to account, start up voltage, max volts, max amps etc.

Choose of cladding material is like any other choice you need to make, you select an appropriate material chooses based on environment. Simple softwood just don't last in most locations, exposed locations have little chance. You really don't need to AI to make that call, just read any best practice guide on cladding installation and design. Softwood ok for your shed - full stop. We used Scottish Larch, no issues 4 years on

Possibly not. You spend some money on professional fees, you can't claim vat on. So even though a limited company you still can't claim the vat back easily. You then have to do a VAT return (think every quarter) annual accounts, personal tax returns (because you are a director), corporation tax, just to maybe have a work around to recoup a few hundred, maybe a couple of thousand. Not exactly a hack (which is a stupid word)

A thing a lot of hybrid inverters will not do. In a power outage the output goes to circuit or two only. Basically configured allowing essential appliances and lights to stay on only. Via a GivEnergy AIO, I've run the heat pump, oven, lights, TV, all in a power cut and my normal string inverters stay online to pass PV to house and battery.

Think you need to fall in the insulate well or no insulation (as longs as floor is direct to ground) camp. The little bit of insulation doesn't charge ground well and if it does the insulation stops it coming back into the house. So it's just energy lost.

No idea of the answer but don't hit it - our grind contractor did, got a huge fine. Makes quite a mess

You have not missed anything. You will have extract in the en suite and plant room. So air will be pulled though the house. You still need to balance flow and extract rates overall. Air will sort of following the red lines and be extracted following the blue. So whole house is covered. Use a couple of coanda nozzles at top of wall by cycle room and the air will travel across dining room before dropping down and being sucked to extract points.

The 1m rule only really applies to R290 heat pumps. R32 doesn't make much difference.

Sure you can. But 30 mins one guy did ours. Why bother with the faff, the double checking yourself. Straight from cad drawing to actual marks on the ground. It also positions house globally correct for position (longitude and latitude) and height from a given datum.