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Hello I feel a bit of a fraud as I am not actually doing my own project, but after looking at a few forums, this one seemed to be about the best for technical advice on heat pumps, so I hope I can be indulged. Our position is we are having an air to water heat pump system installed, fully funded by government grant (so we have no choice of installer). They say they will be installing a Vaillant 5kW monobloc, a Joule 150L high gain slimline tank and 7 radiators. There is no existing wet central heating, only Fischer radiators. In their design they have used an oversize factor of 1.9. If I am reading the MCS design guidelines correctly, to be in the green zone with normal emitters the minimum factor is 2.4. They have assumed a flow temperature of 55, which as I understand it is when the heat pump is at its most inefficient, and even then according to their own figures this will be insufficient to heat some of the rooms because they will only use standard radiator sizes, ie K2 and 600mm high. I am thinking that in the future we will want to change some or all of the radiators. So in the longer term I might be looking for advice on how to go about that. In the shorter term I will be looking for advice on setting the system up, because I don't expect them to spend too much time on that. I am guessing it will be the most basic control system, so also perhaps advice on upgrading. In the immediate term, I will be looking for advice on what to look for on things like pipework sizes, etc.

I have a Mitsubishi Heat pump connected to a radiator system via a buffer tank. I also have a DHW tank connected to the heat pump. On the MelCloud app, there is a provision to "Set tank Temperature" Is this the buffer tank or the DHW tank? It doesn't seem to match either in my case E.G Set temp 45C and buffer tank is 34C and DHW tank is 42C If it is DHW tank and I change setting on MelCloud, does it adjust setting on FTC5?

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

Thinking about the hot summer which is now upon us, and my heating for next window. I have GFCH and a big (10 kWp) solar array, facing E/W. I can't do anything physical to the house currently as half of it still stuck in a family estate. So I'm looking at this kind of thing - a portable a/c, which comes optionally with a heat pump, which I have not seen before. Or a slightly smaller version of the same. https://www.appliancesdirect.co.uk/p/airflex15/electriq-airflex15 Power consumption appears to be around 1.4-1.5 kW for 3.2-4 kW of benefit. Does anyone have any views? These are not as efficient as installed aircon / heat pumps. For heating I make that a CoP of 2.5 . But for my circumstances, with an aim for a solar driven cool or hear boost early in the day, this looks quite good. And might stop me boiling now and let me leave the gas off for at least part of this winter. And there's a returned and refurbed series of them available at £325. Any comments are most welcome. Ferdinand