robin coles

Hi Severnside, Thanks for the answers, I get it now. As you say ours is the same idea; a big rectangular main trunk line is fed warm air from the plenum chamber and this then branches off to the rooms. And our water is identical to you so haven't got that additional load for any potential ASHPs. Can I ask "We put 3 Air to Air split units in new part connected to a separate outdoor unit" So is that something like the ceiling mounted AC units in each room or do you mean it's one of the ones that get hidden away but with 3 ducted outputs from the heat exchanger? And heated by an separate outdoor unit? So you've got two ASHPs have you? In our case the heating demand from those three additional rooms we've got is not always needed so we could go for some of these electric panel heaters that so often get advertised these days. But for now we have to stick to the Dimplex Quantums as due to the main house heating we have to be on an Economy7 tariff. Thanks Robin

"Also a colleague of mine is having a new build done in France and he's having a Mitsubishi air to air heat pump distributed through ducting to wall outlets. Each outlet is motorized and has it's own thermostat. The gear my mate in France is using is here. https://www.orionairsales.co.uk/mitsubishi-electric-air-conditioning-pead-m100ja-ducted-concealed-inverter-heat-pump-10kw36000btu-r32-a-240v41550hz-9921-p.asp However, rather than the internal bit being a slimline ceiling void unit (as shown in that link) he's having a rectangular box type unit that sits in an internal cupboard and, I assume, receives the warm air from the external heat pump before sending it into the ducting." I can now provide an update to my mates system in France. As above it used the Mitsubishi heat pump but the inside bit was a French company called Aldes, specifically the Aldes T One Air. This has as least two models; one for air only and one that does air and domestic hot water. https://www.aldes.fr/products/t-one-air (right click - convert page to English in Google) You can clearly see that it's basically just a heat exchanger and fan assembly unit. Below is my mates installation He told me the two white flexi hoses are two and from the heat pump. The two grey on the RHS are flow and return to his domestic hot water cylinder (I assume this may be standard immersion type but with two elements i.e. one heat pump and one electric top up). The other grey lead must be power. As I said previously his goes into a ceiling void ducted network and then down in the wall to wall vents, each one with a thermostatically controlled auto shutter. This is on a new build though. They also do the https://www.aldes.fr/products/t-one-r-aquaair as below which integrates the immersion cylinder Unfortunately still not found such a product in the UK and just been rejected by another two installers. Simply won't touch air to air. @severnside in your pic of the new distribution unit are each of the four outputs going to individual rooms i.e. 4 rooms or do they sub divide again? It's just that size ducting (obviously I'm guessing at the size ~100-150mm diameter maybe?) seems very similar to what we have from 1965! One of my concerns though is that our current night storage heater supplies warm air to 10 outlets, though one is now blocked off. And even that leaves 4 rooms that were never part of the main heating system so currently have stand alone Dimplex Quantums. But if we hoped to include them on the ducted network with an ASHP that's 13 outlets that look very much like your 4.

@ProDave - ok thanks. I did have a look at some air to air source heat pump specs and I see what you mean w.r.t the outputs.

Thanks to all for the informative replies and sorry for my slow response (just picked up 4G heading into port from the N.Sea!) @Gooman - that pdf looks really good. I will consult that if I take this idea any further. @ProDave - yes, you are correct that model does indeed contain asbestos in the insulation. Can I ask why you say to consider an air to water heat pump and not air to air? @SteamyTea I've done a rough heat load calculation is an online calculator (dimplex website). The default desired inside temperature was 18°C for all rooms bar the living room which was 21°C. I thought that was a bit low so upped it to 22°C all round. This comes out at 20.04kW or 68379 btu's. I would have to do a more accurate calculation and cross check across different websites. Thanks again to all for the replies

@Gooman Heritage heating and cooling got back to me - they don't do domestic. I've been going down this road for years. Seems like it's going to take a few more.

@Gooman thanks for your reply. In our case the ducting consists of a main rectangular trunk which comes directly away from beneath the plenum chamber, without measuring I'd guess at 50x30cm. There are then circular offshoots to each room, probably 20cm in diameter. The circular bits do leave the main trunk at right angles but that's it, it's then rounded 45's as required to get to the various room vents. I see your concerns w.r.t your existing system. I would assume our all electric night storage system runs at lower temps than yours. I can certainly put my hand down that main trunk at about 3m from the source with no ill effect! Thanks again for the reply ill get straight onto that company you found

We have a blown air system through rigid metal ducting. It's a Creda Electricaire Night Storage heater which whilst it's still going I have been trying for ages to find a replacement heat source and have been wondering about air to air source heat pumps. I came across this company who seem to be offering it https://www.mittensheatpumps.co.uk/heat-pumps/ducted-vs-ductless/ It has to be doable; such a retrofit is common place in the US where blown air systems are much more common, there's a whole video about it on youtube. Also a colleague of mine is having a new build done in France and he's having a Mitsubishi air to air heat pump distributed through ducting to wall outlets. Each outlet is motorized and has it's own thermostat. The gear my mate in France is using is here. https://www.orionairsales.co.uk/mitsubishi-electric-air-conditioning-pead-m100ja-ducted-concealed-inverter-heat-pump-10kw36000btu-r32-a-240v41550hz-9921-p.asp However, rather than the internal bit being a slimline ceiling void unit (as shown in that link) he's having a rectangular box type unit that sits in an internal cupboard and, I assume, receives the warm air from the external heat pump before sending it into the ducting. It's frustrating as that unit he's having would sit over my existing plenum chamber (the entry point the duct system) exactly where my current night storage based unit is; it seems so simple. I've enquired with the company that installed my solar panels and who do offer all renewables but they don't know anything about it. My feeling is that not many companies are going to or are going to simply say that as they don't want to get involved in something different. Unfortunately, mittenheatpumps have told I'm too far away for them to consider. Though I have asked them if they can provide me any more info about how and what they've installed so far. Hopefully some of this info is useful and maybe soon I'll find a solution Robin