jamesdiyer

Hi all, I've had a few quotes in, the best one 15k eur is using Domusa Teknik machine (Spain based). The other quotes 22-24 are using Vaillant. Both are similar size Domusa duel clima 19 HT / Vaillant aerotherm 16 This is a significant difference in quote price. I know Vaillant are good, but it's hard to stomach that much more upfront. Does anyone have experiance of Domusa Teknik? https://www.domusateknik.com/en/dual-clima-ht#catalogue Thanks

Thanks good food to consider when specifying a ashp size, and good reason to not under spec. Yes, when I say backup, it could mean a 250l tank running separately for the loft annex or running in tandem with the main system. Night electric is cheap here so easy to heat up over night.

Spanish Pyrenees at 1000m. So cold like Scotland. Each floor is about 80m2. No gas to measure, we have a huge wood boiler, but running it at 50C keeps the house quite warm. I feel I modeled it quite accurately in heatpunk (I'm a civil engineer so not unfamiliar with it) and got 12k iirc. I said 14 give or take because I modeled at 18C everywhere and didn't include one currently unheated room in modeling, plus hadn't accounted for DHW if needing to.

Thanks. It's not 14kw with DHW. Currently got 250w immersion which would likely be kept as a backup and install a new tank linked with ASHP. Normally it's 2 adults and 1 kid but can go up to 5 adults and 4 kids if floor 3 annex is inhabited.

Thanks. I could insulate between floor 2/3 but only with about 50mm board. Floor 3 will have wet UFH (it's a shell currently to be renovated). Yes appreciate the thoughts. I'm uninclined to undersize the ASHP as when a big storm rolls in here it will be brutal for 5-7 days, so even with internal fire place to take up some slack, it's a risk. I'd rather be right or just over sized, and look to improve insulate as best possible. I will have a look at modulation on different brands, but it sounds like it will be similar. I'd be tempted to buy the best modulating one. But ultimately will defer to installing company due to then being able to invoke warrenty if badly sized. I'm outside UK so MCS etc isn't a concern.

Thanks for the input all some good thoughts. We have 3 pannel radiators on 22/15mm pipe from the wood boiler, so moving to ashp they should be ok, they're sized ok (having modeled on heatpunk at a 40-45c flow rate). The house is 800mm stone wall. The floor 3 is stone, insulation, brick with well insulated rafters. The inner floors are non insulated concrete slab. Though I had considered insulating between 2/3. Each floor is about 85m2 mostly ontop top of one another. So yes, perhaps just ways heating the loft works out. Intend to run the system open with no buffer, it's a large system. Was more to shut off supply to floor 3 when not in use. Thanks the the modulation tables and cycling information, I figure I can work out system volume and see.

Hi all Great resource here and knowledgeable people, so thought I'd sign up for your thoughts. We don't have gas, and I want to move away from our big wood boiler. ASHP seems a good option however... We have three floors. Floor 1: Living space (has fireplace) Floor 2: Bedrooms Floor 3: Independent annex (could have fire place) We will see -7C or so in winter. The annex will not always be used so does not necessarily always need be headed - though it might need be heated somewhat always, so that the delta isn't too great and can be heated to 19C if needed for use. Floor 1/2 are always lived in and need heating. So I come to modulation. Floor 1/2 seem to need around 10kw and floor 3 around 4kw. So to power all three we would need 14kw (give or take). The issue (in my mind) would be on mild days (mornings can be very cold by we are south facing so by mid day quite pleasant) where floor 3 does not need heating (empty) but floor 1/2 do and a 14kw heat pump is needed to run at a low %. I am struggling to find good technical data on minimum power input/output for some pumps (as I've seen noted here in other discussions), which seems to be my critical point. I do wonder what the optimum solution is. Two heat pumps? One unit and heat Floor 3 anyway on mild days One unit and accept some cycling will happen on mild days Don't use ASHP on mild days but use floor 1 fire place for heat. Use heat over night and morning and turn off during daytime letting internal temp reduce. I guess overall I lamenting the lack of min output modulation infomation. Maybe I am over worrying a non issue. Thanks