JohnMo

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.

No we didn't render at all, as I hate the stuff. I used stone slips and Scottish larch cladding. Inside we did a lime, cement parge coat for airtightness, and sevice void for from battens screwed to durisol and the dry lined with plasterboard. Doing it again I would miss the parge coat and use a smart air tight vapour barrier membrane, less mess and quicker.

You need a structural engineer for the rebar calcs. Durisol had a really good build manual, you should be able to find it online.

Yes DC over the long run, just use normal armoured cable of the correct size. The more vertical the panels the more even the production is over the year. You get a slight lower yield overall but more when you need it. Mine are vertical and more like a fence. I took the 9m2 as floor area it takes up. 40mm thick is a lot of panels

Durisol costs nothing to brace, well 4 sheets of osb and some screws. Nothing wrong with durisol, our external walls took us 4 weeks, (70m x 3m tall) neither of us (2 off) had done or used ICF and neither of are builders. Yes from recycling mostly old end of life pallets, very little cement, made in Wales. Easy for anyone to build from. Render and or plaster directly to the woodcrete. U value of 0.14 out the box, zero cold bridges, very little rebars required. You actually screw things to the woodcrete without issue. Lots of things to like.

A small heat runs out flow rate by the you get to +/-1m3/h. My 6kW heat pump was flowing just enough to drive 9 (7 in house and 2 in summer house) loops from about 15m away from the manifolds. Had a dT of 4 to 6 depending on room. But the return temperature from a thick screed/concrete floor will dominate max flow temp you can achieve during a heating cycle, without a mixer. Mine rarely has a return temp above 27 to 28 (electronic mixer set to 35), so no matter what flow temps I may ask the heat pump to do my flow is capped at about 32 to 33.and takes about 8 hrs to get there. So trying to spread the heat evenly between radiators and UFH without some form of mixer isn't going to work well. If I drop my mixer to control to 28, so I get plenty of floor water recycling the heat pump does increase flow temp because the house flow temp is less dominant. But I have to run the heating most the time.

At the start of the heating season I was trying to optimise running the house and summer house UFH systems on a common flow temp without mixers. Turned up the heat pump flow temp to 32 from 29.5, also increased the dT on the house UFH to decrease output as far as I could and keep the heat pump happy enough. Basically the house overheated after about 18 hrs was up to 24 degrees, even though the thermostat stopped the demand for heat, the floor had absorbed lots of heat. The summer house wasn't warm enough. If you want two flow temps use a mixer.

Maintenance needs would take several life times to recover the capital costs. How many people actually service their cylinder annually - would bet not many, as many would have no clue they needed to. Heat loss would suspect more heat is lost from the pipes than the sunamp or cylinder. Can't answer your question about energy lost over 24hrs as we keep using it.