SteamyTea

Or a decimal place is in the wrong place. I would expect the highest usage day would have the lowest CoP, during the recent cold snap.

Worth putting temperature probes in the slab anyway. https://m.ebay.co.uk/itm/DS18B20-2M-Waterproof-Digital-Temperature-Temp-Sensor-Probe-DS18B20-UK/192870453965

Yes, they work in any orientation. Only two mirrors directing the light after all. You can get posh and incorporate some lensing by distorting the mirrors.

You are going to notice that forever. I painted my bedroom ceiling, missed a bit, about the size of a 10p piece. I see it every day. Bedroom is next on list to be decorated.

Welcome I would look at your local councils planning policy. Or offer to buy the land.

Is it glass reinforced plastic?

Can you make a periscope that pokes out the side, maybe built into a porch.

We can keep it open, as long as we don't get rude.

So one where of the year where you have used an extra 270 kWh in a week. Divide that over the weeks in the heating season, say 30 weeks that is 9 kWh/week, not a very high price to pay.

Why should they when gas is <3p/kWh

Did you buy @pocster's walk on glazing?

Do these people do anything. I have done some work for then in the past. https://www.monodraught.com/

I think most will. we have a strange rule when claiming RHI, that cooling mode has to be disabled at commissioning. This does not mean ASHPs cannot cool. RTM and see what it says. (if you need to cool your house, something has gone wrong in the design)

Be about 3 tonnes of water. Storage heaters would take up less room.

Is this the dungeon door. Are you inside the room or outside it?

Is it in here, page 15. Tell the vendor that it is a non RHI installation. https://www.google.com/url?sa=t&source=web&rct=j&url=https://www.daikin.co.uk/content/dam/document-library/declaration-of-conformity/heat/air-to-water-heat-pump-low-temperature/ehbh-cb/EHBH-CB_EHBX-CB_4PEN383118-1C_Installation%20manuals_English.pdf&ved=2ahUKEwjc_I6svfHuAhWdQkEAHfyWBjYQFjAEegQIFBAB&usg=AOvVaw2zhfl3ZrOUkvtQGRsPArBy

Excel and Google. Someone like @PeterW will know more about the intricates of the actual set up.. But 45°C seems high if it the flow temperature into the UFH, probably fine for radiators.

Calculating the heat losses between each room of the house, as well as any losses to the outside. From this the heat emitter sizes, and at what temperatures, they will operate best at, can be calculated. From this the heat source can be sized correctly. It is the same as going an external wall, floor, window, door and roof heat loss, except some rooms will have different temperatures i.e. living rooms and bedrooms. It may seem a bit of a faff, but it should help with setting a system up.

Which may be called Disinfectant

Two things, how much insulation do you have under the floor heating and do you have a buffer tank fitted?

I think the only risks you run about only heating some part of the house is that you run the risk of short cycling and you may have to run the flow temperature higher. Both of those will hurt your CoP. Have you done a room by room heat loss analysis? This may show you what flow temperatures are optimal. On @ProDave's point about having radiators on part of the system. The power they can deliver is a function of the surface area and the temperature differences. If they perform well at say a flow temp of 40°C, then this should not be a problem and the UFH should have a temperature blender to reduce from this. It really does depend on the system design. Do you have a buffer tank fitted?

Not yet, but my phone must have.

I can. It can use historical usage patterns. Does your system have a buffer tank?

Why wait, this house will be around for decades. Aim for an overall U-Value of below 0.15 W/m.K and airthighness of under 0.75 ACH@50Pa (get a test done while you can still fix things, a test us less than a bathtub). If you are going for underfloor heating, design in 250mm of I dilation now. And integrate shade free PV into the roof

I think 100mm of celecotex gives a u-value of 0.22 W.m-2.K-1 If your UFH is running at 35°C and the void under the block and beam is at 5°C, that is ~7W.m-2 or 0.16 kWh.day-1. Keep adding in floor insulation.