JohnMo

The additional heating is either a relay output to fire an immersion in the central heating system, or an additional boiler. These can be needed for extreme weather cases, where the heat pump cannot cope.

As @Nickfromwales is aware my real life view of woodcrete ICF is very different from his. We have never had any water come through the walls, no damp issues period, 5 years and counting since the walls went up. Yes we did parge coat to the inner wall for airtightness, 2 days work. We then attached 50mm battens (service void) and then plasterboard. Out of all the systems (Durisol) was easiest for me, no special props required etc. Just simple had tools.

Forgot to mention DHW, this was to be by immersion only. Have rethought this, as all the hardware and cables are in place, to switch the 3 port valve. But gone a much simpler layout than previously. Immersion is standalone and not connected to heat pump at all. Any issues with heat pump, just flick immersion on. Routing was always difficult to sensor probe from heat pump to cylinder but that has been solved by repurposing a cable or two not in use, that running through the house. But includes the cable I was going to use for the smart grid switching. One problem solved, one created.

Jobs done today The feet I bought to go underground the heat pump were 1m long, so trim them down to a more manageable length of 800mm. Moved the heat pump from patio to closer to the final location. Used a simple garage trolley located under the manufacturers pallet. Next job is to cut off the pallet away at the light end (condenser end) and affix a foot. This will give something to lever against so when in final position the remaining pallet can be removed and the other two feet added. Completed all wiring as far as possible. So 3 core cable for power, 2x0.75 screened cable to outside unit and further 2 core to the smart grid connection (can't complete this as cable from house is currently connected to other heat pump. I heat the summer house as part of the same zone as the house, it runs at 18 to 19.5 normally, but sometimes we need it warmer, so I normally use a thermostat to trigger a second setpoint for the heat pump, which works fine and floor just buffers the heat. The Hiaer unit, I will utilise the smart grid connection, and set a 2 Deg uplift in flow temp when the connections across terminals for SG2 (EVU signal) are closed. The same connection can reduce the cooling flow temp should I need it. Also made some covers out of excess OSB from the house build, to cover some gravel I need to travel over. Looks like next weekend to do the heat pump change over.

You can cover this in another thread rather than clogging this one up. Just need to start it.

Trouble I have answering this thread is the heat pump control is being somewhat taken over by another 24v system, so it's a can of worms. Simple made difficult.

When I did my new build I priced up Fresh-R, but got push back from building control on flow rate not matching building regs. But the concept is good and can be made to work with ordinary MVHR units, using cascade ventilation. So extract from all wet rooms, add air in a central location, so it passes through other areas before being extracted. Between room fans if layout demands it.

No chlorine, so not really pool type water. Will monitor pH and drop and top as needed to that in check

No, but also not using any chemicals either, so no need for titanium heat exchanger. ASHP not connected yet. But when running, modulation down to 1kW should mean it just runs, so should never see the 14W on its own and should be accounted for in the running CoP.

It's just being repurposed - the 6kW unit will be used to heat 1700 litres of water (hot tub). Just been outside with dog, while I was waiting about I was feeling all the edges of the metal, everything seems nice and rounded off, nothing sharp at all. 90+kg to move about, that will be fun - not. Set up the controller this afternoon, only thing I can't do is load the WC curve, because the unit doesn't see the flow and return temps as no outdoor unit is connected. Had a look at the electrical draw The whole wiring centre and controller pulls a continuous 14W.

MVHR dies summer bypass automatically cannot change it, not sure how it helps, unless it increases heat demand, which not sure below the back pocket

Nope not enough cooling effect. UFH in cooling mode leads to a nice house

It's minimum modulation is near 4kW, house demand is only 3.5kW max. Normal run of things I wouldn't change it, but we have just bought a wooden hot tub, so will repurpose the old unit to heating the hot tub, instead of the normal wood fired heater. So get a heat pump more appropriate to the house demand. Should make a decent dent in running costs, with better CoP in summer and winter, for very little money.

Didn't answer fully before

There is the inverter controller outside but I think the indoor wiring centre controls most things The relay is for cylinder immersion control. You can drive a couple of secondary pumps, mixer valve, 3 port valve etc. plus lots more.

Yes and Wolesely don't tell you any different. They want a restocking fee to take it back. They do sound small, I keeping my 50L volumiser in system so will retain the existing expansion vessel in circuit.

Just need some warmer weather to allow old heat pump to be removed and this one installed. Have had to add antifreeze valves, part of the warranty conditions. Have got Inta Zero ones that reference water temperature not air temperature. Brand new half price bargain from eBay.

Some photos Indoor wiring centre with controller installed (no wiring installed). Simple install screened cable to outside unit and power. Cover on and wing complete, all metal casing and very heavy duty. No sharp edges. Outdoor unit, for a 4kW unit it's pretty big, the condenser and fan are very big compared to the Maxa unit currently installed which is a 6kW.

So took delivery of the 4kW Haier ASHP today. So far first impressions are very good. Consists of an outdoor unit, complete with expansion vessel and pressure relief valve, inside the monobloc. Inside the packaging is also a controller and indoor wiring unit. So can return the one I thought I had to buy. So total cost is £2100 delivered to the door from Wolesely. Photos to follow with full install story

Heat output is governed by mean floor temperature or mean radiator temperature. A heat pump that can modulate down to match heat energy required and not cycle, the target flow temp will always be lower as it can run steady state. So to deliver a mean flow of say 30 degs with a delivery temp of say 32 and return of 28. A cycling ASHP no matter how minor, to deliver the same mean flow temp will have to operate a higher target flow temp to compensate for the periods when the compressor is off, so CoP takes a hit. Also data table assume steady state running not any cycling. So do not take account of any energy wasted reheated cooled down components. But as previously mentioned, if a oversized heat pump has a suitable depth of modulation your only hit is capital costs. Which could be in the thousands as everything becomes bigger to accommodate the increased flow rates and electrical loads. Which aren't the dominant use case. The coldest days are the few and more average 7 degs days are the many.

So are new one

Run in DC not AC, then volt drop isn't an issue

Heat pump cylinders are generally big because they store water at 45 to 50. A typical direct cylinder could just as easily be at 70 degs, so effectively a much smaller cylinder holds just as much energy.

Can you not surface run it?

Get your finger out!