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Hello buildhub residents. My first post here. I'm self-building a passive house in East Anglia and I'm looking at heating, DWH and potentially cooling solutions. My question is this - a load of companies seem to manufacture units that are either multi-split of mini VRF and have A2A refrigerant inverters available with a hydrobox for DWH (that's my reading of the marketing docs, please correct me if I've misunderstood the technology) But NONE OF THEM are available in the UK it seems (I hope I'm wrong, but I've called them and nobody knows anything about these units here). Does anyone have a good sense of why they're ether not bothering with the UK market, or why they're unable to get them licensed here? Maybe something to do with the distortions created by the Boiler Upgrade Scheme? The list has most of the big guys one it: Mitsubishi PXZ series - see around page 25 of this pdf here: https://kokotasgroup.gr/entypa/pdf/FULL_PRODUCT_HEATING_WEB--281-29_6166.pdf Samsung EHS TDM Plus Climatehub - https://samsung-climatesolutions.com/en-gb/b2c/our-solutions/home/heat-pump-solutions/heating-cooling/tdm-plus.html Daikin Multi Plus - https://www.daikin.ie/en_gb/product-group/air-to-air-heat-pumps/multiplus.html Panasonic Aquarea Ecoflex - https://www.aircon.panasonic.eu/IE_en/happening/aquarea-ecoflex/ LG Multi-V compact with Hydro kit - probably too big for my house, but anyway https://images.b2bmkt.lge.com/Web/LGElectronics/%7Bc5c4ca24-a96c-4aed-9cc9-97e1f6dbabf2%7D_2023_4Q_White_paper_Hydro_Kit_Low.pdf? ArgoClima iseries split - https://www.keaneenvironmental.ie/argoclima/iseries-split-pump/ Midea CirQHP- https://www.prnewswire.com/news-releases/midea-comes-to-ish-frankfurt-2023-with-its-latest-water-and-space-heating-solutions-301774592.html And yet - nothing available in the UK....

Can anyone give me a quick summary, or link, as to the minimum practical external temperature for A2A heat pump installs to function? Background is that I am currently using GFCH underfloor downstairs / rads upstairs, and I have been experimenting with a portable A2A heat pump heater / cooler for about 18 months in the kitchen diner. I am satisfied that it puts off any need for GFCH use by a few weeks either end, a boost to the house via air flow, and gives me a nice cooling facility in high summer. But my unit says it is not practical below 7C external temperature. Were I to look to install A2A units as an eventual replacement for the GFCH would that limit be about the same ie not much use below 7C? Hence my question. Thanks in advance for any replies.

Anyone had experience with sizing A2A heat pumps (ie. Mini/multi splits) for heating loads? Have had a few quotes for fitting out our house now, and sizes from contractors have varied quite a bit. I’ve tried my best to approximate heat loss requirements using MCS heat pump sheet, as well as Jeremy’s sheet from the forum, and approximating existing radiator input. Often coming out with significantly lower numbers than any of the contractors. A couple examples: (House is detached chalet bungalow from late 90s, brick with filled cavity walls on GF, timber frame with 50-100mm insulation on FF. Located in South East.) Our lounge is a 25m2 room with 3 external walls and decent amount of glazing. MCS calc indicates probably 2kw losses, radiators (3) seem to add up to about 2.2kw. Contractors suggesting a 3.5Kw or 5Kw wall unit. Seems like 2.5Kw at most would be sufficient?? Looking to do ducted to 3 bedrooms upstairs, one about 20m2 and the others both 12-14m2. MCS seems to be about 1.2kw for the big one and 500-700w for the other two. Contractors wanted to do a separate 3.5Kw unit for each bedroom, and one contractor said 5Kw for the large bedroom. I am thinking we could get away with a single 3.5Kw unit ducted to all 3 rooms! (Daikin even does a plenum with motorised dampers to control individual room temps to a degree) So am I missing something? Or are the contractors just vastly over sizing (as seems to be the case with many in A2W?) The units themselves aren’t massively different in price as you go bigger, but the running costs almost certainly will, particularly if they end up significantly oversized. Any input is appreciated

Hi, My house I brought is 1920's and previous owner fitted ASHP air system only for heating. Now house insulation is poor so why it was fitted I do not know but this was around 10 years ago. My question is in my loft the ducting runs all over, is insulated. But the actual loft insulation is very poor. Can loft insulation be laid over the insulated ducting, or would this cause potential condensation issues?. Any help would be really appreciated.