Air to Air with hot water systems

DC999

Also interested in this one. I reckon any heatpump we get will be A2A due to cost and ease to install. But want to see the running costs too and see how they stack up over the life V A2W

mp3guy

Daikin Multi+ 4MWXM52A2V1B9 with EKHWET120BV3 DHW tank and 3 indoor units (2x FTXM25R5V1B, 1x FTXM20R5V1B) commissioned last Friday. AMA! This is in a detached newly built auxiliary building, indoor units heating hall/landing and then 2 upstairs rooms.

micks_address

https://www.boards.ie/discussion/comment/121454792#Comment_121454792

Would love to hear more about it..cost etc to install and running costs.. kWh usage etc

mp3guy

I don't have an itemized breakdown, the cost was rolled in with the rest of the plumbing in the building. As for running costs, currently trying to get a handle on this. Unfortunately it was just turned on at the start of this cold snap and the building has had no heating in it before so I think drawing too many conclusions w.r.t. to energy usage in these early days might give a poor impression, I'm still trying to figure out the best temperature settings etc... But I will update with info as I gather it, hooking up things to Home Assistant right now.

mp3guy

Right so early data:

Apparently it took 10.4kWh of energy yesterday (Wednesday December 6th) to heat a hall, stairs, landing, bathroom, office and bedroom. Stats were pinned between 15c and 16c, because the units appear to heat 4c higher. So if you set them to 16c, they'll heat to 20c according to their own stat. But, if measured with an independent thermometer in the room, I got 18c actual maintained temperature. Average outside temperature was 10c. Average wind speed high at 40km/h; this is a detached building with only shelter from the north. Trickle vents open in just the bedroom. It's a 70sqm area that was heated in total, 25sqm of it taken by the hall/stairs/landing/bathroom split. So 0.43kWh per hour on average. Humidity in one room measured bang on 50% all day.

Still figuring out the best way to set the devices' target temperatures and whether or not it makes sense to put them on a typical day/night schedule when the building isn't occupied.

DC999

https://www.boards.ie/discussion/comment/121466424#Comment_121466424

0.43kWh per hour is brilliant for 70sqm. I am using that much just for the 25sqm sitting room+ kitchen.

Does the unit show any COP stats for that data? Then we can see what the 10kWh multipled into in actual Wh of heat.

Remind me again what is the BER or how we'll insulated is it?

mp3guy

It's a new build garage w/home office on 1st floor with modern insulation/air tightness. No BER but assumed A. So caveat is the car port area beside the hall and below the living area upstairs isn't heated.

The unit is disappointingly sparse on data, it seems like Daikin have kneecapped this unit, or at least stripped out telemetry maybe to lower the cost?

All it currently exposes is the kWh used by each air conditioning unit is, it won't even give me the DHW draw (I've emailed them about this).

There's a very detailed datasheet here however: https://ddugroup.ua/wp-content/uploads/2022/05/4mwxm-a_data-books_eeden22_english.pdf. The outdoor unit is relatively low power.

I am having an issue at the moment where the DHW tank isn't heating up unless all 3 AC units are off, which I suspect is an issue with install or configuration as this goes against what they say it can do.

I've been using two Home Assistant integrations to pull out data:

https://github.com/rospogrigio/daikin_residential/

For the AC Units and:

https://github.com/speleolontra/daikin_residential_altherma

For the DHW tank.

graememk

https://www.boards.ie/discussion/comment/121467527#Comment_121467527

Apparently measuring CoP on a2a is more difficult than wet systems.

It was mentioned on a skill builder video when he had the guy from heat geek around to a person that adopted early to a heatpump and it never worked right

DC999

https://www.boards.ie/discussion/comment/120449973#Comment_120449973

@Jackson22 and @The devils how are the a2a systems behaving now we're a few months into the heating season?

Is that the only heat you are using or still failing back to gas or standalone electric rads in places?

Would u recommend to replace a gas boiler with them?

Ta

listermint

On a basic level my understanding these are like traditional wall mounted type units. But how do you get the heat to every room in the house.

From a physical standpoint do you have to pipe all rooms ? (Note I've got a new mhrv system)

Or does it rely on heat dissipation via open doors. Which seems like it would be uncomfortable in cold rooms and warm in closer rooms.

What's the expected operation from a logical stand point ?

micks_address

https://www.boards.ie/discussion/comment/121471991#Comment_121471991

From what I've seen you pretty much need a wall unit per room if you want heat in those rooms. You need ducting to each unit to run piping to and also need to be able to pipe moisture outside from each unit

listermint

https://www.boards.ie/discussion/comment/121472000#Comment_121472000

Seems an unreal level of faff and realestate.

Not a fan. Would prefer centralised system. Never checked if my existing MHRV has similar option for a2w. It has low level resistive heating element for frost protection but nothing designed or intended to efficiently heat

micks_address

https://www.boards.ie/discussion/comment/121472031#Comment_121472031

The main advantage I see with it is potential cooling in summer and removal of radiators.

listermint

https://www.boards.ie/discussion/comment/121472069#Comment_121472069

Agreed. But I refuse to be running AC in summer don't need it. Mhrv fans do the job and our house orientation and T shape design means it doesn't heat up any of the rooms. It would be less efficient for me for AC.

unkel

https://www.boards.ie/discussion/comment/121472031#Comment_121472031

In my case I just need 2 big indepenent mini split units, one in the living room and one in the kitchen / dining / conservatory (with heat pump outside right on the other side of the wall). I heated the entire downstairs of my house with 2 large mining rigs for years, not touching the central heating

The beauty of course is that the install is then super simple and cheap. As in complete professional install done incl. parts and labour for around €3-5k for A2A with two minisplits (incl. far IR panels in the bathrooms) - we don't heat bedrooms, instead of €15-20k for a full house A2W professional install (not even talking underfloor heating install obviously)

I can't see the savings from the extra COP (of about 1-1.5) ever paying for the extra €15k install cost during my lifetime even if I stayed in the house and lived to be 100 years old 😀

listermint

https://www.boards.ie/discussion/comment/121472328#Comment_121472328

I think my missus would murder me without heating in bedrooms

unkel

https://www.boards.ie/discussion/comment/121472369#Comment_121472369

As you can gather from my above post, we do always leave all doors in the house open, so a lot of heat goes from the downstairs to the upstairs, so even on a cold night the bedroom would still be at least 17C by midnight. A good quality duvet will heat up the person in the bed very quickly and if not quickly enough for herself, she can use a good old hot water bottle or an electric blanket 😁

But agreed the bedrooms would be too cold for anyone staying there for some time. The kids use far IR panels in their bedrooms / when they are studying, etc.

All my electricity use in the house is from 5c nightrate (so far)

JayBee66

The problem is, how many rooms should have a heating unit. I imagine it's different for everyone and different for each house. I have 6 non-wet rooms and a hall in a bungalow.

The living room could be stove or A2A dependent on how cold and if I collected enough wood the previous year (I pull bits from the river and from woodland).

Should I heat the hall and let it dissipate into bedrooms and main bathroom? Should I heat the two main bedrooms and not the hall. Then there's the reception cum office.

Is having 4 units in a bungalow too many or should I have one beast in the hall to do the lot with stove back-up in the living room? Do I trust an installer to do what's best? Are there really as few installers of A2A as my Google search says there are?

I was quoted 12K for 4 units by the most well-known A2A installer, which seems an awful lot. I don't expect A2W to be much greater and it would heat every room via the radiators.

poker--addict

12k sounds an awful lot.

Muahahaha

https://www.boards.ie/discussion/comment/121447888#Comment_121447888

Have had an air to air system installed almost 4 years now. Its Mitsubishi units, Ive only one unit downstairs as the upstairs bedrooms already had panel heaters, the A2A system was replacing a 25 year old storage heating system on the ground floor.

Im very happy with it, it has all the bells and whistles like wifi control and not just acting as a heater but also air purifier and dehumidifier. And then in summer it comes into its own with air conditioning. When I bought it I didnt even know a2a systems for heating are basically air conditioners running in reverse cycle. So when we had that 30 degree heat wave in summer of 2022 I was sitting in a cool 16 degrees while friends in brand new homes were complaining how hot it was and opening all the windows did little for them. Id only use the air conditioning function about 10-12 days total most summers but when I do use it then it is fantastic to sit in air con comfort while it is roasting hot outside. Was funny that summer when I had friends over for a BBQ and it was 32 degrees outside and everyone wanted to be indoors sitting in the air con to 16c.

On performance iirc the manufacturer claims between 2.1 and 4.1 efficiency. I doubt it ever achieves 4.1 but between 2 and 3 is what I feel it delivers. To give a concrete example my October & November electricity bill in 2018 was 252 euro. Then my October & November bill after the a2a system was installed in 2019 was 157 euro. So all other things being equal it was a fair bit cheaper to run than the storage heating it replaced.

Both units cost 1,300 in 2018 and the installer charged 500 to install it. The grant at the time was 600 but you had to get a technical inspection plus 2 x BER reports which came to about 600 anyway. So I forgone the grant and just went direct. Overall Im very happy with it

unkel

@Muahahaha - thanks for sharing. Bit confused though you say you've only 1 unit downstairs, but later you say both units cost 1300?

DC999

Each gaff is different. One in sitting room / kitchen and one in hall would largely heat our small house. IR heaters in 1-2 other rooms would cover the rest. We don't heat bedrooms. Hall heat covers that.

Plus it gives air con for the few times of the year it's needed. Our redbrick heat cooks all day with sun and then releases that into the walls at night. House is too hot to sleep. Live on a main road so can't leave windows open due to road noise all night. I disagree with using energy for the sake of it. But if you can't sleep! Back to each gaff is different!

Someone talked about space needed for units on the walls. How many meters of wall space do rads take and we can't use anything in front of them?

Cost: 3.5k grant V 4.5k for a2w. If the install cost is far lower....

unkel

https://www.boards.ie/discussion/comment/121474181#Comment_121474181

I don't think there is any grant at all for A2A, is there? Or have I got that wrong in my mind? I seem to remember I don't qualify for it anyway.

JayBee66

https://www.boards.ie/discussion/comment/121474181#Comment_121474181

That's the problem; a Goldilocks problem. I don't want too little A2A or too much. I want it just right. I worry that the salesmen are only interested in how much commission they can make and the technicians, how much equipment they can shift.

It's not really possible to have a little A2A and some again later. I only want the one outside unit so it has to sized for the job.

With the electric heaters I have now it's a case of imagining how much more heat would be nice. If a heat pump's COP is beneficial or (at our age) if just having more electric heaters with the euipment saving is better. I'll give the Wallrock insulated wallpaper a go to see if it slows down heat loss some more. The only thing I can do after that is external insulation. Heat loss is 1.91 though I didn't think much of the person who said so.

JayBee66

https://www.boards.ie/discussion/comment/121474619#Comment_121474619

The last time I was in contact with that well-known A2A installer, they said it has to be a whole house A2A install (I assume that means every room - where possible) to get a grant but that was over a year ago.

unkel

https://www.boards.ie/discussion/comment/121474933#Comment_121474933

Yeah that rings a bell alright. For me the beauty is in a system that has an easy and cheap install. Labour cost never pay back. So that means two simple mini splits in two rooms and that's it. No ducting between systems, just simple inside + outside units

micks_address

Is It possible to add air con units to an air to water system?

graememk

https://www.boards.ie/discussion/comment/121475210#Comment_121475210

Depends on the a2w system.

Some can do cooling. But nothing straight off the shelf anyway. Rads need to be plumbed differently (in the top), and run at above the dew point.

Possibly could DIY something with this

Would need some sort of drain for the condensation!

DC999

https://www.boards.ie/discussion/comment/121474924#Comment_121474924

Have a look at shiva aircon crowd. Saw their ad and the do air con in a single space (one wall unit) and pricing is like 2k supply and fit. That would cover our sitting room and kitchen. That might work for us. As you say, not too little or too much.

Might be old pricing. Excludes getting core hole drilled in wall and sparks work.

unkel

https://www.boards.ie/discussion/comment/121475845#Comment_121475845

What does it include then, just delivering the unit and hanging it on the wall? 😂 Sounds crazy expensive to me.

Mitsubishi (very good reputation) 3.5kW (presumably output) full mini split system, £525

https://www.ebay.co.uk/itm/275726393502?mkevt=1&mkcid=1&mkrid=710-53481-19255-0&campid=5339017931&toolid=10049&customid=777_777_777&gclid=CjwKCAiAvdCrBhBREiwAX6-6Urs7wjUUUEX242tXY8lJZvoJW1y8rfaNepanTejc4H7DSyGhVAmRiRoCZJ8QAvD_BwE

Samsung (very good reputation) 3.5kW (presumably output) full mini split system, £589

https://www.ebay.co.uk/itm/185646558391?_trkparms=amclksrc%3DITM%26aid%3D1110018%26algo%3DHOMESPLICE.COMPLISTINGS%26ao%3D1%26asc%3D20210609144404%26meid%3D664c12633494407893a6434c31c3a849%26pid%3D101196%26rk%3D1%26rkt%3D12%26sd%3D275726393502%26itm%3D185646558391%26pmt%3D1%26noa%3D0%26pg%3D4429486%26algv%3DCompVIDesktopATF2V3WithQueryItemRecallV3%26brand%3DBrand&_trksid=p4429486.c101196.m2219&amdata=cksum%3A185646558391664c12633494407893a6434c31c3a849%7Cenc%3AAQAIAAABALHyIAEaemKG0mx4REjf%252BHxECBsXtSkNHsCLmXz%252FJyCDeX%252FaDb78456J9CQJiWkf1shIoHZumq%252F1uABNIGYIBECYjqWR6N4wzkKMBSySUkKUJiw2UI3W4hVw6aHN9o4od14n8yatUHxgRmoOOnL%252BzvjTEHXRU%252BbGlZrSiFlVtd%252FJx8sKf3YQEhuHYllUCCvZCslGdQ1EPF5UHitc6u4aO068%252BOXlhRWptYWi2l64v0nyCA78lDRk8ssgc3hiRS7h5ivQDEum2IFQs5ig9Dbs62RuiuUUvQzUTtY2q7XY4RRlN%252BnhJ8LKZAqQb1e%252BG8vROKsKQwg3tG2naC4qe%252Fdub%252FE%253D%7Campid%3APL_CLK%7Cclp%3A4429486