JohnMo

Get company installing to measure, then any mistakes are in them.

Too many snippets of information and no real drawings to what's what. It can't be hard.

Still confused about all the ground beams and where they fit in with the insulation. If they are actually ground beams and insulated raft, will it be with lots of thermal bridges?

So daft question where is your insulation for the floor?

Not if it's closed cell insulation. If it's not closed cell then vapour barrier is needed

Most insulation is fine it's all generally closed cell. If you are concerned about pipe condensation you need to install condensation drains for the fan coil also, with a dry trap. Or just put a small container under the drain point and empty as needed

Most heat pump have the settings built in, but the logic is to basically control a mixer to let down (or up) one set point to the other.

So I assume internal walls will be going in. Map out where the rooms/internal walls are. Then do circuits/loops in each, and take those loops through the doorway into room. Your loops do not go the the very edge of room, so stay either side of a wall by 150 to 200mm then you have quite a bit of leeway. Sort of like this

You could do the same or similar with a wet system I assume, with UFH scheme in the ceiling and then run from heat pump, and you would have pretty effective cooling also.

Electric not metered so not that much idea, but pump will only run for a short while. Annual service is about £100 to £150, filters, UV light etc.

Our only treatment is particulates filtering and UV. But due to our borehole being in pure sand (34m depth of it) we had to steel line the bore hole, so an additional treatment was needed to eliminate iron oxide. If left untreated would turn all water users brown. So treatment may not to to expensive any way for whole house use.

0.07 (W/m²) x 192 (my house area) x 24 (hrs) x 0.25 (kWh price standard tariff)

Isn't there an issue with pace markers? Many manufacturers not recommending it? Wouldn't include 'only' as 70W per m² is still high. That would 'only' be £80 a day for me on a standard tariff. Where as with my heat pump and some decent insulation I would be closer to £3 (at -9, on octopus cosy, and 192m²)

No, unless you are a BIG user, like a farmer, domestic user no.

Don't think it gets confused it just monitors return temp and responds to that. But will it modulate down, while doing hot water. Mine certainly doesn't, it runs full load and full circulation pump speed throughout the whole DHW heating cycle. Some heat pumps allow different settings. Not so sure about that. Once heating cycle is complete the cylinder will stratify as normal I did a slimline cylinder

Based on not just you, but future buyers of your house, as it's a bunch of tax payers money. So bedrooms, rather than sizing for me and my wife, in any number of bedrooms.

The other bit in MCS rules to which the BUS is linked to has a specification for cylinder and number of bedrooms - is the cylinder big enough to comply?

Get a borehole? Then you stay in control of costs, not some big corporation, that passes it's fines on to you to pay.

We generated a 3kWh today, far from self sustaining here. The joy of being north.

The way the heat pump operates doing DHW. You have a target flow temperature, let's say 50 degs for ease. If the cylinder is at 30 degs, the heat pump will sense a return temp of 30 degs, and add a dT to flow temp (approx 5 degs). Now as the cylinder heats the return temp increases as does the flow temp to keep the dT constant. This gives a good CoP as temp stays low as long as possible. Now the rub, if your heat transfer area is smaller than ideal, the coil doesn't extract as much energy as it should, so flow temp stays higher than it should. So the ASHP runs at an elevated temperature for a given cylinder temperature. The more flow and return diverge away from actual cylinder temperature, or more distortion you have between cylinder and return temp the worse the CoP. Worst case is you do not hit cylinder target temp in one hit, you could end up cycling the heat pump, but most will have a learning feature saying it don't succeed heating cylinder with ASHP, so I will just use the immersion instead. Best situation is a huge coil 3m² or larger or a plate heat exchanger. An add on phe and pump is the easiest way to do things, choose a bigger PHE get a better CoP.

A bog standard gas heated house, with low standing electricity loads, it's never going to be viable for a battery. Not sure how you make the maths work. On the other hand, an all electric house, with stuff like a treatment plant, with a continuous compressor running, borehole pump, ASHP etc and PV. The argument becomes more compelling, way easier to justify. Really each case will have a different break even cost point. Mine was a no brainer and just part of a series of changes to bring utility bills down substantially. PV maximise, ASHP, battery to utilise generated PV, smart meter to get a decent electric tariff. Back in 2023 with gas and electric we were paying about £220 each month, now down to below half of that.

I suppose it is likely render was originally put on an uneven substrate - rubble etc. so likely you will never get a flat finish. Leave the past behind - you are doing a new build embrace it

But maybe run long enough that battery technology gets cheaper and allows more to be installed with out breaking the bank

Really depends on tariff and how many bites you have at charging. When charging your house, it will be using grid energy anyway - if no PV. So on cosy you can easily charge 3x a day and get 7 hrs off peak. Which is a lot of cheap energy even with a modest battery. Trouble with big water storage is modest PV it makes almost no difference to the water temperature, plus with no PV you always have to throw plenty of energy in to it to make useable flow temperatures. What are going to do with the hot water when you have it?

I suspect it will turn like Australia did, you now pay to export, not get paid - unless it's to the benefit of the grid, i.e when it's not windy or sunny.