JohnMo

Water cylinder is why cheaper than a sunamp. £3k v £1k size for size, spend a little more get an A rated cylinder like OSO, the heat loss is low also. 300l, start temp 30 finish temp 56, circa 9 kW. Which takes back to big buffers/ thermal stores.

Why not replace the whole things will slim line led fittings they are about 10mm thick. Possibly a bead of sealant to stop drafts. Example of light fittings, I mean https://www.toolstation.com/led-slim-round-panel-light/p71575?store=LJ&utm_source=googleshopping&utm_medium=feed&utm_campaign=googleshoppingfeed&mkwid=_dm&pcrid=558038224734&pkw=&pmt=&gclid=Cj0KCQjw1tGUBhDXARIsAIJx01kit9HU4Z30HFIGvtfHDQNDi6WQvOSsinvm_jkeYgKNOTkA2ocQ7ZQaAjvaEALw_wcB&gclsrc=aw.ds

Small section with the same cross section should be ok. If you worried about noise, insulate around the changes in cross section shape. If it's the same cross section the velocity will not change. Noise is generally flow induced by velocity. You should look up the pressure drop caused by the transition pieces to ensure they are low pressure drop.

Options 1, 2 and 3 all put an insulator (plywood) above the UFH pipes. Option is a cement board and much less of an insulator, so I would go for that. Could the boards be glued down?

Looks like a hard way to make a stud wall. Are there any benefits over 3x2 studs.

Hope you don't go lots of mph, and get a low mpg, while spending your decimal £.

Another nonsense, waste of tax payers money - more living in the past

You be using hangers according to most design guides I have read. design_a_deck_planning.pdf

But they did not say 0.013kW they said 0.013kWh per day. Two different units.

Bought mine new

Think it's the same, but not much losses in when it gets to around 30 degs during heating season. Any other heating is by solar which will get consumed during heating season. But may get toasty in the summer, we will see.

I bought this from eBay. Which is the same as mentioned above, even comes with insulation. Item number 304182801695. This is it installed but used PIR insulation.

Most tray manufacturers do repair touch up kits, they aren't cheap for what they are. Pretty much the same as car touch up kits.

I think it depends more on how the bearing and compressor are lubricated. The compressor can run dry with bearing away from the refrigerant gas or be lubricated with compressor flooded with oil, the same oil lubricates the bearings. Sounds like the ecodan compressor is a flooded compressor, the lube oil works fine while the compressor gas is in the gaseous phase, but when it turns to the liquid state; on compressor cool down, the lube oil no longer lubricates. So a typical start up would be, heat oil within the compressor, flash off refrigerant to gas phase start compressor. Possibly a 15 to 20 minutes delay in startup. So during the heating season the operation of the heat pump, would be, lowest temperature for central heating possible run 24/7 (weather compensation) except for when doing DHW heating. At least that way your standby losses are confined to none heating periods.

Wow - Is that £400+ to be in standby for a year? Just found this article on the subject from 2013, they should certainly drop the eco from the name. https://heatpumps.co.uk/2013/08/13/stand-by-power-and-air-source-heat-pumps/

PHE Sized for. Primary side 6kW input at 27 degrees supply 22 degrees return. There is an additional return temp drop as flow goes through primary coil on its way to the boiler of about a degree. Secondary side 25 supply and 21 return. So an approach temp of 2 degrees. Using PHE (Hexonic LA34) with a size of 471x81mm plates x40.

Don't stair designs have to be approved by structural engineer?

I using a 160l thermal store as a buffer, standard coil rubbish when using low temperature flows. I have just added a large 40 plate heat exchanger as well as the coil.

Two ways to look at things, pump a fair bit of heat in over a short period as you are. Trouble with your approach is air temp is coldest (at night), flow temp at 45 quite high so CoP not the best. Doing the same thing in the day CoP would be better. I am doing similar but with gas boiler but flow temp is 30 for an hour or so longer. 24/7 running with very low temp or weather compensation. Tend to get best CoP heat pump ticking over, little or no stop starts. Heat pumps tend to be least efficient when starting as a far of energy goes in to heating the system and components back up. Think best way to find what is best for you is trial over a week for each approach record comfort and energy use. But both need to be run at as low temp possible. I am going to be trying both approaches again myself next heating season, looking at low/mid 20s flow temp.

May also depend where you live city or county, we have to have a lay-by arrangement at the entry so postman van can park of the road and the first 10m of drive from road edge tarred to road spec. The rest has to SUDS compliant, so self draining. We are on a slope so are having crushed stone with lime through it; so it sets into position, while being water permeable.

Expanding on Gone West comments The maths for downward heat loss in simple terms is Equation. U value, multiplied by area, multiplied (flow temp of water - ground temp below floor). For a given flow temperature. Poor u value, lost heat downwards is higher than upward heat transfer to room. To compensate the flow temperature is increased. Good u value downward heat loss is low more heat to room. To compensate flow temp is decreased. Troubles come with poor u value, as your downward becomes large, so to get a suitable heat supply to the room you have to flow at a higher temperature, (as too much heat energy is going down) which further increases your loss downwards. (flow temp of water - ground temp below floor) this part of the equation becomes larger. In simple terms that means a u value of 0.1 or better, flow temp mid 20s, 0.2 u value, flow temp could be in the 40s for same conditions outside the floor area.

And they are?

As you have a nice well insulated extension to the old building, the whole building is now a sum of new and old parts, not just the old parts. So as far as energy usage is really s new building it not all new and it's not all old. If the EPC only covers the old, it is out of date and needs to include the new part also. As you say easy done and is issued as a new EPC. We had to do same when we renovated and converted parts of the building that hadn't been used for a hundred years.

Run round the show houses in your area check out the bathroom fans, we checked our local ones prior to building, dMEV was very difficult to hear. Non dMEV made a racket. Your choice your money

Or they need to turndown the thermostats and/or the flow temperature at the manifold. We have UFH, it gives a very even spread across the whole house all the time. Basically don't operate like a radiator system, lots of on off cycles as you are wasting energy. Two modes of operation, chunk heating, a few hours to charge the floor, then leave the heat to slowly release or very low temperature for a long time. We tried the later first, but with well insulated houses the normal manifold mixers don't turn down low enough. We tried min setting at 28 degC and overheated somewhat. So went to chunk heating 6 hours at 30 degC which worked fine. Have made mods for next heating season, so I can reliably get to any temp I want, maybe somewhere close to 24/25 flow temp.