JohnMo

Grant heat pumps can now use Homely if this is useful to you. Should optimise the system for you once the installer has left you to it.

Can I ask - How noisy is the indoor unit?

Are you just making life hard for yourself? If you are using ground screws for a good reason. Would you not bolt bearer beams to the ground screw and the the floor panel to the beams. You may be easier Ground screw Bearer beam 22mm floor panels Insulation (floating) either EPS or PIR Floor panels (floating)

Have looked at Larson strut for the walls? Your 225mm studs will create a thermal bridge at each strut. Which you are mitigating with external insulation. The Larson strut, uses 2 smaller studs joined together with ply or OSB. So you would have say two 4x2s, or a 3x2 and a 4x2 with a gap between, the gap maintained by several pieces of the OSB nailed to each stud. One stud is structural The other to form a depth for insulation. The thermal bridge becomes the cross section of the OSB instead of the stud. You can make a good depth of wall for insulation and could save the time and effort of external insulation as well.

I am just running E7 and it's currently averaging out 30% cheaper than normal rate on a 24hr basis. Have an ASHP and battery.

Should be called Octopus 'battery' really, that's the only real use I see with it, having an ASHP is just a bonus.

Plus make sure you have CO alarm in the room. Plus make sure you have enough air available for correct combustion, if it's not fed direct from outside, do whatever building regs or manufacturer manual says.

Why ask the question if it's all ok

The pump is there to pull flow through the mixer, the boiler pump will not do that.

Yale do a door slightly open lock you can add. No door will really stand up to a crow bar. If it's a glazed door an automatic centre punch the glass and just walk in.

Our ICF build (Durisol) I did 6 blocks high and then concrete filled.

You can get colour mixed spray cans to RAL codes. Sorry been a while since I purchased, I just did a Google search. You can get 2K acrylic, which is very wearing and not dangerous to use. You can also get different gloss levels.

I would actually ask them to quote for approved alarm and without, I did a few years ago and not one penny of difference. But having the alarm meant you had to follow a given set of rules to ensure you got paid if you were robbed. To be approved you cannot self install, it has to be a professional install, with appropriate certificates and managed and serviced.

Agreed, mine does, but means you cannot use the multi purpose contacts fir other things. The OP said So possibly his heat pump will not have on/off contacts or the installer hasn't read that far in to the installer manual.

Two resistors, 10p each and a relay in a box £5 to £10. No programming or anything special. Plus you need to output a resistance not input it. Taking an on off call for heat from the eDual and output a resistance to fool the ASHP into starting DHW heating.

The bit answered is about measuring switching via a resistive temp probe i.e NTC or PT100. I pointed out away to simulate have a cylinder temperature probe. You are not switching any load directly you are just simulating two resistance output that coincide with a temp above and below a permissive to start heating DHW via the heat pump. The wire size in the probes in the order of 0.5mm² suspect the signal voltage is in mA scale. You would not be load switching that's a different animal as you point out

Trouble with planning you have to do as agreed or amend the planning application. I would be inclined to give the minimum information, less to be tripped up over, if they need more info, they will ask for it. I had to change the location of the boiler, I just amended the drawing to show new location with make and model, they already had the datasheets.

Bit of of a strange layout would be better having the bedrooms together and living/day spaces together. Also lots of bedrooms for very limited living space. Massive hall space being used for nothing much. Lots of bedrooms (people) for one bathroom. Just looks like the wrong house, trying to be used, for way too many people. You maybe better doing a wrap around instead of two extensions, then rejigging the whole space to be a better layout. Or buy a different house

Glad to hear it seems working.

May be worth a read https://www.heatgeek.com/balancing-heating-systems-the-ultimate-guide/

Seems most important aspect of house pricing is how many bedrooms, doesn't matter if you can't fit a full size bed in there, as long as it classed as bedroom.

We have CO2 monitor, a mandatory requirement in Scotland, once your airtightness starts to get to a responsible level, I think it starts to glow red above a predefined ppm CO2.

Prices do come down and new technology will be around every corner. You could wait for ever, or make decision and move on with your life? I am saving £2-3 a day in winter with the battery, the other three seasons will be quite a bit more. Will prices fall that much in the next year I doubt it, will they still be vat free (starting Jan 24), this time next year?

No idea where that cost comes from, lots of PV, battery and ASHP, house running costs way less, not more. No idea what this means - what incoming supply?

Just scrap all the giving money away, let the market sort its self out. PV has been left to find its own feet, for the last couple of years - you can now pick up 405W PV panel for £50+ VAT.