JohnMo

Not sure that is true. I don't have one For your heat demands 10kW is way too big. Nothing wrong with the Grant units though. The 10kW unit puts out 11.1kW at 7 degs, you will most likely only need about 1kW. Get the small one 6kW. Find a different plumber

You need dMVHR in every room to be effective, so gets expensive. dMEV cheap as chips, costs buttons to run and buy. Only fans in wet rooms. You really need decent trickle vents that active on humidity or are self regulated.

Do exactly as they say, otherwise you will have a month delay. I sent warrant plans when they asked for planning drawings, got the a rejection letter...

A combined, MCS heat loss spreadsheet and shite in and shite out from contractor. Cylinder temp does not need to be above 50. UFH will be closer to 30 to 35 I suspect. If your max heat requirements are close to 3kW, you really need to look at heat pump turn down as that is a big pump. Biggest issue will be required flow rates for water. 3kW only requires around 10 l/min, you may have to manage 20+?

I have a buffer for one zone, but changing the timing and flow temp a little has allowed me prove it's actually not required, so will be removed next month, along with electronic mixer and pump for UFH. Will reinstate a small WC of 3 degrees, starting at 3 degs OAT and stopping at -3 OAT.

The wall section has plenty of cold bridges to sort out. You insulation should form a continuous unbroken line, you seem to have breaks everywhere. You I beam bolted into the concrete, just straight through the insulation, lots of condensation will occur. The steel by the glazing also looks the same.

https://www.bpdstore.co.uk/glidevale-energy-saver-humidity-sensitive-trickle-ventilator/p/182 Plus the links I added above. Also look in the ventilation section on here, plenty of mentioned ones there also. The other thing to look at is self regulating trickle vents. I paid just £300 with certificate.

Fig 2 has a curve already built in.

Can have benefits and also pit falls. Breathable from a moisture perspective in is good, breathable from air exchange perspective is not so good as it drives up energy costs.

My battery is in the plant room.

I certainly managed, but running a target fixed temp mostly in the E7 period is just cheaper. Also if doing WC why do zones?

Pretty accurate, trouble with winter and spring the variability of the weather and variable usage My forecast (from Solcast) for the next couple of days, the white is the low forecast the pink is max and the orange line the averaged expected. A lot of variability. It also takes zero account of temperature. Today heat pump barely ran, tomorrow will also barely run, the next day it will, so although the prediction tool looks back (consumption) and ahead (PV output and averaged out consumption) it's a bit of a finger in the air during the heating season. So although home assistant knows what happens in the past and therefore predicts the future likelihoods, the likely scenario on the 9th it would see low consumption on the 7th and 8th build that in to the kWh likely to be consumed on the 9th and give a short fall in SOC at the end of my E7 window. When heating with a heat pump and you get variable weather (we all do), and this part of the picture is missing it isn't or cannot be best placed to accurately predict. @NailBiter what forecasting tool are you using?

My point was the solar forecast said I would be doing 18kWh today, so far today with 2hrs of generation to go I have only done 7kWh. Plus to fire up the dishwasher or washing machine someone needs to fill it, machine learning doesn't really help. Possibly 5 months of the year good, rest of the time too hit and miss. Been caught a few times where I ended up importing expensive electric because machine learning said I could charge the battery to 50% as solar forecast said xkWh generation expected and it didn't anywhere near that. Nothing to do with location, insolation, azimuth, pitch, size of the array. Used the excess manually today, oven on making granola, washing machine on, dishwasher on. The rest diverted to DHW.

I was thinking something similar - have a detached garage some way from the house. It has water, I have a no longer used thermal store, roof does have some shading, but may be workable.

Is that really a good thing, short cycling comes to mind.

I assume you don't really mean S plan, but 2 x 2 port valves one normally, the other normally closed, so you don't feed the cylinder as well as the UFH, at the same time. I would keep it simple with a 3 port diverter - normally closed side to cylinder. 4 zones is likely to require a buffer also. Have you considered that? If you are doing a buffer 2 port is best. You would connect something like this (below image) the room thermostat would control the heating pump only - top right of cylinder, the buffer cylinder would control the heat pump on off. If you are well insulated and airtight WC is an unnecessary complication. Tried every conceived option and a set flow temp is easier. To be quite frank, if you have anything remotely thick in way of screed the Wunda thermostats are too big a hysterisis, to give very good control.

A smart TRV is just internet connected, a marketing ploy to make things sound better than they really are.

Live looks to short for that. Got a solar forecast app for the battery and that's a pain, might be ok May to August, but the rest of the year a lot to hit or miss to be relied on.

Just to finish the thread off Over the winter the solar thermal didn't really earn it's space, it did generate some energy when the sun was out, in short bursts , but not enough. So the panel was removed yesterday. May find a summer use for it, but not really why I got it.

I have these, different outputs for different pipe spacing and mean flow temperature

@Post and beam should read this.

No need, one is fine

That is a good point, irrespective of build method used if you want decent insulation values in the walls, (any build method) they will be quite thick. My durisol walls are not thin, at the front (cladding external and battens/plasterboard inside) are about 600mm thick, rear (stone slips) 500mm thick.

Think you need to step back slightly. What is your expected heat demand? That will determine the heat pump size. Your ideal is no buffer at all, but if you have lots of zone and some are quite small you will need a buffer, but size depends on a few factors, tied to the expected ASHP minimum output and flow rates needs. 2 or 3 port buffers are better than 4 port as there is generally less mixing going on inside the buffer.