Heat Pumps: AIR TO AIR or AIR TO WATER?
ฝัง
- เผยแพร่เมื่อ 5 ก.พ. 2025
- In the world of heat pumps, there are two prominent types: air-to-air and air-to-water. But which one reigns supreme?
If you're a homeowner looking to upgrade your heating system this video is for you.
We'll delve into the pros and cons of each system, exploring factors such as installation costs, comfort and convenience.
By the end of this video, you'll have a clear understanding of which heat pump type is best suited for your needs.
Watch Tim's conclusion • Air-to-air vs. air-to-...
@TimAndKatsGreenWalk
#HeatPump #HomeImprovement #EnergyEfficiency #CostAnalysis #HomeRenovation
--------------------------------------------------------------------
One off donation: buymeacoffee.c...
Regular support:
/ @upsidedownfork
--------------------------------------------------------------------
Sign up to Octopus Energy for a free £50 - share.octopus....
--------------------------------------------------------------------
My videos are made with DJI gear.
Osmo Action 4 Camera - amzn.to/3MHvybO
DJI Mic 2 - amzn.to/3XoQAkx
--------------------------------------------------------------------
My system :
Vaillant Arotherm Plus 7kW Heat Pump
200L UniStor Cylinder
45L Buffer tank
140sqM Detached 1997 built house
10mm copper microbore pipework downstairs
Installed by British Gas
I had Air to Air fitted in June and so far im really pleased with it , i have a 3 bed house and only 3 cassettes fitted downstairs and the house id fine , it only cost £5k andd was fitted in a day with hardly any disruption at all. i dont have hot water but i will get under sink heaters for the little water needed , i have an electric shower but even at 9kw its negligible the amount it uses for a 5 minute shower. i have found that when i have the heat turned up high it isnt using hardly any more power after the room is upto temperature running around 3,4,5,6 hundred Watts, last month i used 407kwh ,
PS , there is a power cut now from the storm but everything is working fine with the powerwalls , Good review
Interesting I also have a 3 bedroom house.
Air to water fitted cost just under £4000.
Trickles along at around 500w most of the time
Nearly every pipe was replaced in my heating system.
I used around 280kwh heating and hot water in November (total house usage 433kwh)
@@Burtis89 i do live alone so i suppose i use less but i do have the livingroom emp high .
Thanks for commenting!
I think air to air is a good solution for a lot of modern new builds. Generally well insulated but absolute hot boxes in the summer that cooling would help with. Additionally a lot of new builds could do with freeing up radiator space!
Thanks for commenting.
I had A2A in my last house and now I've moved to a bigger house I went for A2A again without hesitation. First off its very cheap to run, I've had my bedroom unit on all night set at 18° my whole house is drawing less than a kilowatt including the background stuff. It's very very quiet on night-time mode less than a ceiling fan and without the expansion noise of radiators. I've set the air direction to ceiling only and diffused so I can't feel it (Midea call it "magic air"! ) but best of all it dehumidifies (excess water is pumped outside ) so no damp or black spot mould. In the summer this is an absolute heaven, my wife and I sleep far better with this on set to cool, even dust is reduced because the circulated air is filtered which is great for my wifes hay-fever. It means we can keep the windows shut excluding night-time dust and noise.
In the kitchen the unit helps tremendously with cooking humidity and is our preferred way of drying the laundry. We place the washing on a rack under the unit and it's dried nicely without creating condensation.
We have two small outdoor units, (we opted for that as opposed to one large one because it is quieter (the neighbours say they cannot hear anything) and as we rarely run everything at once running costs are reduced).
Inside we opted for 4 units Lounge,kitchen and two bedrooms.
Total cost fully installed £6k and very neat and unobtrusive. Our hot water use is minimal so we went for a small efficient gas boiler.
With the lounge unit on the sound level is 25db taken approx 10foot from the unit which is up in a corner. Again the air circulation is set to "diffused" and the temperature set to 23° giving a humidity of 46% .
Thanks for commenting
It’s the industry/government one size fits all (air to water) mentality that gets me. Totally agree with all your points. Regarding air to air and noise, if you’re willing/able to pay a bit more you can get quieter indoor (and outdoor) units.
Bedroom cooling for a couple of weeks in summer is worth its weight in gold and was a big factor for us in going the air to air route.
A point to note, you can’t put an indoor unit in a bathroom, but you can have airflow ducted from a separate unit. We went for a mirror IR panel for the bathroom.
Thanks for commenting!
Oh! that's interesting about not being able to put a unit on a bathroom wall. Is that a regulation?
@ Lots of rules on where and what electrical equipment can go in a bathroom. If you can find a unit with the correct IPx rating and it’s fitted in the appropriate zone then it may be ok but you’d have to do a lot of checking.
About A2A noise levels, it depends a lot on the make and nodel of your equipment.
When on vacations, my mother always complained about how the noise of the AC unit (either for cooling or heating) wouldn't let her sleep.
Then I installed one A2A from Mitsubishi Electric and she like it so much, she installed similar A2A units on her house and she never complains about noise.
Not all A2A units are made the same....
Thanks.
Tim's latest video goes some way to addressing this. He clearly has a good system and now runs the fan on minimum speed which I guess contributes as well.
@UpsideDownFork it does.
When my parents chose theirs, they were considering a slightly cheaper Mitsubishi Electric that besides not having the auto setting for the fan, it also lacked the quiet setting so I convinced them to spend just a little bit more and get the same I had, just to be sure.
They never complained about it being loud and neither do I.
Very interesting vid.
We've had a single split unit in our bedroom for years for cooling in the summer, and a gas boiler for all rooms.
During Covid I decided to do a loft conversion, putting 2 bedrooms in the loft. Thinking the loft bedrooms could get hot in the summer A2A was researched. We opted for a 4 way split system, 3 bedrooms and the living room on one outside unit. ~£4k fitted with all pipes hidden as they were fitted during first fix.
So now we have limited gas hot water heating in the form of 3 Rads and UFH in the kitchen, utils and hall.
A2A is great, heating the living room from 19°C to 22°C in 15 mins and tick over on minimum fan for maintaining temp. Bedrooms at temp within 5 mins. With the quick response the units are off until needed and only rooms that need heating get heated so zoning is east and all run off an app.
No noticeable draft unless your under the unit. Noise isn't an issue on low fan speeds, you only need higher speeds when you want the temp to change fast, once your in steady state the fan is low and you cant hear it.
Only down side is when someone puts one unit on cool when another is on heat, doesn't happen often, but kids being kids will try and cool the room in winter using the air con!
Also no energy monitoring on our unit. That said I'm starting to tie in monitoring into my home auto so that will come. The plus point of using home auto will be all energy monitoring will be in one place (Openhab) so any calculations will be automatic and easy.
We also have PV on the old FiT (so no energy monitoring on the inverter as its too old) and solar hot water which the FiT covers most of our energy bills. As for HW, the solar covers us from May to September with no gas used. Further areas I'm looking at another PV array the the dormer roof, battery storage and heat pump for the wet side of the heating.
Keep up the good work we all need this info to make informed decisions.
That sounds great! Thanks for the feedback.
It's always reassuring to hear when people are making informed decisions for their use case.
Great video! Having lived with air-to-air for three years... I'm still not sure which I'd prefer in our new house! The cooling was amazing in summer, it was extremely cheap to run, and the near instant heat is fantastic. However, it just didn't feel cosy enough for us. Especially when it does its defrost cycle: suddenly you feel very cold for 20-ish minutes while it stops working.
That said, both are great solutions and each work for different homes/families. Anything's better than burning stuff.
Thanks for commenting!
I'm interested to see what you do for the new place.
@MrEV Hi, I do get defrost cycles but not that often and not for 20mins. About a minute or two at most.. It may suggest that either your unit size for the room was wrong to start with of the outside location isn't ideal. A larger inside unit working less hard might of been better. The first company I used I was very disappointed with. At my current house I used Staffordshire Aircon (no affiliation) who were very knowledgeable and did a great job very neatly.
20 minutes for a defrost seems abnormal - what units do you have?
We had an air to air system fitted in our bungalow because it used to be heated via storage heaters. In this situation I believe it's almost always easier to get the A2A because of the lack of plumbing and the cost + disruption of installing a whole new central heating system. The downside is water but you usually have an immersion tank in this situation so running that off a night tariff isn't the worst. We opted for an instant water heater to replace the old heavily corroded tank, get rid of the gross vented system, make room for a stacked washer and dryer in the cupboard, and (importantly for me I have MS) I can set the maximum temperature of the water heater to be the standard safe temp in hospitals/nursing homes of 45° (so I don't burn myself+ don't need to worry about legionella with stored water which I'm also vulnerable to because I have a compromised immune system from my treatment 😅)
In the long run we might look at getting a heat pump water cylinder in the loft or maybe the small sunamp solid state heat battery if a tiny 2kw air to water heat pump comes to market that we could plum up to heat it. You don't need a lot of output for heating a small cylinder in a bungalow with 2 people but that's below solar+battery on our list of priorities and we might find that the savings of heat storage would be negligible once we've got some electricity production and storage 🤷🏻♂️
The cooling was a big factor for me too because my MS is made worse when I'm too hot. During heatwaves I used to be trapped in my bedroom with a noisy and inefficient portable AC. Now I can roam the whole house at will.
If you spec the right system then control is pretty good these days too. I know that even on cheaper Fujitsu and midea systems you get WiFi control as standard now. We opted for Fujitsu because that's what the installer we chose preferred. Their app is pretty good but it's also pretty easy to integrate the units into home assistant for fully local control and to implement smart features like geofencing and weather dependent automations.
We're happy with our decision.
Great comment, thanks for sharing!
France, who are lauded on their heat pump fitting, you can get a grant for any heat pumps including Air to Air (air con)So out of the figures of 600K heat pumps they fit a year, 420K are Air to Air!
They still fit many more air to water to us, but the comparative figs that the media keep producing are skewed as the UK don't count or give grants to air to air, not even air to air water heaters, which I can't understand.
The problem with those figures is, whether that is per install or per unit. As there are plenty of cases where multiple outdoor units are used for A2A, whereas a single one is used for A2W. So if every A2A install had 2 A2A units, and every A2W install had 1, then those figures are about even.
So you are agreeing with me then!👍
The 600K French figures could be far far less households fitting heat pumps than the massive figs suggest!
that makes other countries heat pump figures skewed as well ! So in theory when they say Sweden is fitting 100K heat pumps, the majority are Air to Air, so that could mean only, say 40K households coz some will be fitting multiple air to air units!!
The UK Government only count Hydronic heat pumps which will be 99% of the time, one unit/household. I have seen a 2 unit set up before on a massive property.
Thanks for commenting!
@jezzaandrews1940 The government seem set on discouraging A2A completely, I had an epc done at my new house after I had finished updating (and got a B ) but annoyingly the guy doing the epc said he couldn't count the A2A as it didn't appear on his list (as in not included ) also no grant. Considering the whole system cost me less than the grant the government hand out for A2W I find that crazy considering how this current lot are pleading poverty.
Yes, if they want to cut down on Co2 and get the number of heat pumps fitted that they want, they need to include air to air systems. Air to air water heaters should definitely be Government discounted.
I understand the worry that more energy will be used in the summer time with cooling of the ATA units, but the grant should be more flexible.
If householders have invested in solar panels and batteries, they are cutting their Co2 consumption and using off peak energy to charge batteries etc. They are helping the planet and the grid! So If they then remove a fossil fuel boiler from the property, maybe the grant should be on a sliding scale, with a points based system, with Air to air in the mix, but with the Government preferred option, air to water gaining the maximum £7500!
Its worth noting that the low and slow method isnt an exclusive advantage of a2w over a2a, because a2a can do it just fine too and is how I run mine, obviously heat distribution isnt quite as even, but things like my bed are very comfortable to get into even though its not directly aimed at by my upstairs unit on the landing.
As others have mentioned, high wall units arent the only option as well and can have floor mounted ones that look more like a storage radiator.
Panasonic also have units with a "windfree" mode now, which can heat and cool without using the fan, but when it needs to it also has some sort of smart tracking where if theres someone in the room it will direct the air flow away from the person as well. Not sure how good it is, but that sort of thing should resolve the complaints of being blown on.
Don't steal Tim's thunder! 😁 He's got a great video coming up to showcase running low and slow just as you are 👍
I have had air to air since 2008 and pellets stove in a great configuration, works great low maintenance and cheap.
Thanks for sharing
i agree with air to air, just because you have fast heat and more importantly cooling, although i feel air to water with underfloor heating is very nice to have as its silent and no radiators, great vid
Thanks for commenting!
Great video, look forward to the next one!
Thanks for commenting!
Nicely summed up. Honestly I often forget air to air a viable option on a larger family property especially when taking into account the lack of grant and hot water. With the exception of Tim and Kat's Green Walk I don't tend to come across many people's experiences
Thanks for commenting!
I’ve got an old oil boiler needing replacement next year and am leaning towards a2a because all my pipes are buried in the concrete floor. I don’t trust they are in good condition having had 4 leaks in the cold water pipes over the last 10 years.
Thanks for commenting!
Very good video; the only thing I think you forgot to mention in the comparison is the amount of space needed for the tank(s) which may or may not be an issue.
Thanks for commenting!
Should also mention you can get central A2A system with fan unit outside as usual but with heat distributed from unit in loft feeding rooms via ducting. No boxy indoor units - just small vents in ceilings. Search central ducted heat pumps Much neater solution with no holes in walls as the refrigerant circuit feeds into the loft.
Agree they are neater but much more expensive with the ducting runs. I was thinking of getting this for my house but as soon as you have a second story the work becomes much more involved.
Thanks for commenting!
put in both be the best answer i can think off couse they compliment each other.
Thanks for commenting!
10 years now with A2A at 53°N, working great, less expensive, simpler. Works very well but only if the house is insulated. 99% are not. We are in that 1% and its fine, aircon does not run at night, no need unless its freezing outside. Energy costs are low, solar panels provide power 8 months of the year, did I mention that this is 53°N and not a southern hot country :-)
Thanks for commenting!
In addition to air-to-air and air-to-water systems, there are also heat recovery ventilation systems and geothermal heating. Geothermal heating tends to have the highest installation cost but the lowest operating expenses.
It is worth noting that air-to-air systems can also provide cooling and is the cheapest solution.
Both MVHR and geothermal are extremely niche and not suitable for most housing stock in the UK.
A2W in many cases is coming in cheaper than A2A due to the government subsidies.
Sorry this video is primarily focused at the UK market.
Love the approach to the analysis; I was more excited by the A2A option when initially investigating heat pumps, but with the grant then A2W seems the more sensible move for us when the time comes.
We have a relatively young gas boiler from 2020, before the heat pump push really began in earnest, so seems less wasteful to get a couple more years out of that rather than scrapping it now, but otherwise I'm very much ready to switch.
(Finally posting a comment; been subscribed for a while and like all the videos when I remember but I never have anything to contribute in the comments 😁)
@@jackbyron2149 thanks for commenting! 😊 Good to hear you're ready for a heat pump when the time comes 👍
Another fab article,
Thanks for commenting!
we looked a A2A but could not imagine having to add the units to every room in the house, it was much easier to simply replace our combi boiler and put the HW cylinder in the roof. Our house is a typical 1970s 4 bed so I had alwas retained the relatively huge radiators, just running them at a lower temperaure on gas, the installation was so simple that it only took two days to fit with all the remaining 70s radiators upstairs replaced even though the heat loss survey said they were OK, modern radiators are much better and don't need painting.
Thanks for commenting!
@edwyncorteen1527 You could of gone for ducted A2A but we prefer the flexibility of individual units so heat on in kitchen and a glorious 16° c in my home gym.
The Daikin EDLA range of HPs are heating only, the EBLA range includes cooling (flow reversal valve fitted), with correct emitters (fancoil units ?) effective cooling can be achieved apparently without condensation issues.
There are some advantages to living in a cold wet climate ;-)
Thanks for commenting!
Both technologies are great but at the moment the grant on heat pumps makes them far better value. Speaking as someone who has had multiple quotes for both options, and my preference probably being for A2A initially, I just cannot justify the extra 10k or so! I do not understand why people why people say A2A is cheaper tbh, maybe if you have no need for a hot water cylinder and have no radiators or access to a 7.5k grant they would be, otherwise way more exprensive option. Great content, keep it up!
Expensive to install, not to run I meant btw
@@tomrichards4633 thanks for commenting.
That's what I found when I got 2 tentative quotes. A2A was far more expensive to install 👍
@@UpsideDownFork Yes I am getting a heat pump installed for about 3.5k with Octopus and that includes a 200L cylinder too. That is about the same as one aircon unit would be, but I would need multiple units (at least 3 in total) and then hot water to sort too!
Once the permitted development updates happen, I'm intending to get A2A in addition to the A2W that I already have. My South facing rooms get rather toasty in summer.
Thanks for commenting!
I lived in the USA, and they mainly heat use forst hot air. It was very uncomfortable.I am going for Air to water
Thanks for commenting!
Great video pal and very informative and balanced. I've just had 16 solar panels fitted and will maybe look at some sort of heat pump solution next. I was drawn to A2A as I heard lot's of negatives about A2W especially in winter months and if you want 21 degrees comfort? But maybe that's just a myth and you can get comfortable temps all year round.
The key point is the sizing. And applies to both A2A and A2W. e.g. Undersized A2A or A2W won't be able to cope on the coldest days in winter either way.
Properly sized and installed, either is a great choice. The main deciding factors are going to be cost (including grants), and whether you want cooling in summer. Also whether you want to go through planning permission or not. As A2A basically always requires planning permission, but most A2W installs will come under permitted development.
Glad it helped!
I worked with an air conditioning xpert about 15 years ago at that time he stated that it cost about 7 pence a day to run it
Yes, they can be incredibly cost effective to run.
I was thinking, when i finally get a A2W system upgrade, of putting "fan coil radiators" into the hallway by the bedrooms and in the lounge. These, in combination with the underfloor in the kitchen, will hopefully mean we have decent cooling options. Also putting bigger column radiators in preparation as they send water up and over rather than relying on convection like panel rads...
So hopefully that'll be enough to take a few degrees out in summer, even if it's not proper air conditioning - 28-30 indoors is uncomfortable, but 24-26 is ok
Thanks for commenting!
As well as Air to air or A2W some people [in the future] may have district heating!
Thanks for commenting!
You forgot to mention district heating being the third option for low carbon heating (available only in certain locations). Fab video on in on the Everything Electric channel recently.
Spirit Energy have just released a video on rewards from mortgage providers - similar to your earlier video.
Thanks for commenting! 🙂
I got one a2a unit on living room of 3bed semi size house with external wall insulation.
I find it keeps whole house warm,runs all day from my house batteries and solar.
Total cost for unit installed £1500.
Thinking of putting one at bottom of stairs to run at night,to send heat upstairs,on low rate electricity.But I could just keep the one unit running?
That's a brilliant result for £1500 👍
Back in the 70s we had hot air heating system it didn’t keep the house warm it was useless so we changed to gas radiator system and the house was loverly and warm , so what’s the difference now do you have special air
That system would have used direct electric heating elements rather than using a vapour compression system with compressor, evaporator and condenser.
Completely different systems. It's almost the same as comparing a steam engine train to a modern refined car.
@ if you stood next to the vent hot air came out but it couldn’t keep the house warm , it was oil powered not electric I was only about 10 at the time but I do remember tankers coming to the house it was useless so we
So what about (ignoring cost) just having both types? The cooling gets handier every year!
That would be ideal if it weren’t for the BUS grant and planning implications. Have an A2W pump sized for hot water and “base load” heating, and the A2A for flexibility and as a peaker plant in the depths of winter.
That's what the B&B in Rye does. Has A2W to provide a baseline level of heat, along with hot water, and then guests can use the A2A to boost it to their desired temperature.
However, in most homes, you will end up oversizing with using both, e.g. for a 5kW heat loss you aren't going to be able to get units small enough for both to work in tandem. So it would be more efficient to use only 1 of them.
Thanks for commenting!
Perhaps a mixture of A2W & A2A is the answer?
A2W for the whole house including the HW & A2A added for specific rooms where cooling might be a requirement in summer e.g. bedrooms, lounge, home office. The only snag with this is that under the current UK permitted development rights having 2 or more outdoor HP units needs planning permission which means extra cost, delays & may be refused.
Thanks for commenting!
I would pick whatever is the easiest installation, which depends on your house. In my case, I had air ducts everywhere, so ducted A2A. I had a separate hot water cylinder, so heat pump water heater. My brother's house has radiators and should get A2W.
@@davidstewart1153 thanks for commenting 👍
We have 2 Mitsubishi Air to Air both 5 kW and it is not that easy to decide.
You get fast heating and it is instantly there, but also only there.
But fast heating comes along with noise.
You need to mount it really high to avoid hit someone.
Multi Split AC are crap if not all rooms connected run at the same temperature.
But the Mitsubishi do not perform as promised and far away from cop, they hide these data and it took years to find the full specs.
You do not achieve the savings promised.
But it can be a chep way to start with a heatpump to get an impression how it works and that it works, but avoid to get 2 at once as we did. Get one installed and make your experience for example with a cheap one in the bath room where it will perform quite well cause you will get instant heat. For elderly this might be a key moment how warm it can get, but then it becomes expensive cause you heat a rather small room only.
It is also a cheap way with 1 unit to use solar power surplus energy effectively during 2/3 of the year as heat and 1/6 maybe as an ac. Again those will be really appreciated by elderly but only in the living room.
When we found out that the chinese air 2 water heatpumps of 8 or 10 kW would only be 1800€ or 1500 GBP.
The air 2 water has come now on top of the oil condensed heating system + split ac + oven incl. heat exchanger.
Why?
a2a can only heat 1 room really good and that depends also on the shape: small rectangles with the indoor unit on the long side might not work that well
The control of such heatpump needs an energy meter for each heatpump with power monitoring for example in Home Assistant. Only there you can see the current consumption over the past few hours and how often the heatpump has made a break cause then the efficiency is poor. Then it runs for 10 minutes and stops for 1 and you get 5 or 6 cycles per hour which will end in bad cop and the compressor will age much faster. Compare it to a fridge by adding such energy meter: that turns on only 1 or 2 times in an hour when the door has not been opened.
You can improve the performance by reducing these breaks by openening doors which means to increase the heat load, but that is limited, rather very limited.
Therefore you need to size it properly which can make it quite expensive. And it is not as easy to install as many think cause a lot of things have to be done or have to be prepared like a more or less dedicated power line. 5 kW heatpump takes up to 2 kW input power which here is limited to 16A or 3,8 kW. So do not connect the heatpump to a socket where you might usually use an heating iron for the shirts and so on cause the breaker will kick in if it is cold. During autum running at 250 W nothing will happen.
Then you need to drill a big whole through a thick wall where things can go wrong like hitting a cable you were not aware of or a wooden column.
Do not forget that they need a water pipe to get rid of the moisture from the inside unit. Do not forget that each of these units outside and inside need to be cleaned carefully and I need for that 3 hours per Split AC - inside and outside all the heatexchanger have to be cleaned carefully where I used for the outside unit (you have to remove all the metal sheets and then you will see a lot of dirt and the exchange unit can be covered with finest particles that water alone will not move away - therefore I clean the whole area with a toothbrush).
Many rooms and this a2a becomes quite expensive even if you can diy cause 2 of the Mitsubishi are more expensive then a chinese heatpump which has been used for years in Norway where we found out that this manufacturer must have a good quality and it is so good that the german government gives you a subsidy of 35 to 70% cause it fullfills all the criteria and has a TÜV certficate, spare parts are available too, supports RS485 protocoll for Home Assistant and has an app and nice display.
So we ordered it from the manufacturer and it will be added into the rear of the condensed oil heater .. below -2 °C we will not use the heatpump and oil only to which is an automatic switch to use 300 L of oil instead of 2500 L for 200 m² but that reduces also the amount of kWh needed to heat during cold days.
If you have many rooms forget AC - I would never buy more than 2 AC again cause the bigger COP and SCOP is more or less a thing from a laboratory which you will not achieve and can be really hard to measure: you would need to days with the same temperature curve outside and similiar temperature before to run the heating 1 day with oil and then with those Split AC where you also have to make sure that in our case you use the same amount of hot water . We did that in a different house with a gas condensed heater too and same results. COP 5 promised at 5°C and roughly 3,3 achieved. Assuming the SCOP 4,3 promised was right we should have seen a lot lower oil consumption cause 1200 kWh used would mean that both would have produced 5200 kWh which equals roughly 550 Liter oil we should have saved, but it was rather 350 to 400 Liter and quite disappointing. Now we get a hybrid system to save a lot due to the hot water topic cause that will be produced far more efficient. How can we now ?
Well, we had 1,25 L daily oil consumption which equals 12,3 kWh but we should use with a heatpump roughly 4 kWh during the summer or roughly mid may till end of september. And the difference is huge if you look at 8 kWh savings cause oil heating becomes inefficient.
So start with 1 ac only and maybe choose the living room where you might want a short time till it is heated up and where you can save a lot. If you have surplus energy from solar power system then it is also a good choice too. The savings in a big room quite often used are higher than in a smaller bathroom. You also have the chance to most likely open 2 doors and heat more rooms too than just 1 small room only . Before you invest in a second Split AC consider the water heatpump and start with those from china cause they are affordable and easy to mount, multiple languages are available and english is quite good translated, but german not so well.
Quality ?
Why should the chinese be bad if they do produce heatpumps for german manufacturers ?
Therefore their heatpumps fullfill all the regulations like SG ready and the german BAFA requirements which are mandatory if the customer wants grants from the government.
So be carefull to invest too much into A2A heatpumps cause in the long run the a2w will pay of faster and better . Do not forget that you need space inside (which is easy) but also for the outside unit like the wallmount and what not plus the whole cleanding topic at least 1 time a year, inside the filters need to be cleaned every 6 - 12 weeks. If you tend to forget that the COP will be getting worser and worser and then it should not be your choice.
If you're expecting a good cop from using it intermittently then you're running it wrong.
I have a single unit on my upstairs landing, it keeps all 6 rooms upstairs comfortably warm, and it's by no means an open plan layout.
Thanks for commenting!
I would put planning permission down as a particular con of A2A. Permitted development is for heating purposes only; "the air source heat pump is used solely for heating purposes" (although someone could argue that during hot spells they are using it to heat the garden). Getting permission for something which could be used as air conditioning is far tougher as some councils check the noise level at property boundaries.
Thanks for commenting!
I am getting A2A installed soon. I was told you only need planning permission if the units are less than 1 metre from your boundary.
@@dennisbean5569 Search for "heat pump permitted development" and find the link to "The Town and Country Planning" legislation. This Class G development only applies for heating. Note that I think you are liable if planning permission has not been obtained, not the installer!
I disagree. There is no planning permission for Air to Air required unless in certain circumstances.
@@lawman1965 If the heat pump is used for cooling purposes then it is not permitted under permitted development class G. See conditions G.3.a) "the air source heat pump is used solely for heating purposes". Is there another class of permitted development that air-to-air falls under?
No VAT on A2A both the purchase and installation
Good point. Thanks for commenting!
It’s fair to say that when the A2W grant ends, prices won’t suddenly jump by £7500. Grants skew the market and artificially inflate labour costs.
Look at what happened when the grant to install an EV charger ended; installed prices were pretty much the same afterwards 😅
We'll see. I suspect you're wrong on that. Unfortunately tradesmen day rates are insanely high and demand is there to keep them high.
Channel members have already seen my thoughts on this in another video that will be coming to the general public next week 👍
Long may the grant continue, but it will be interesting to see what happens when it ends. I haven’t tracked anything closely, but when it increased from £5k to £7.5k I don’t remember noticing that prices dropped by £2,500, based on quotes received by friends and colleagues.
@@HowardBurgess hey, I may be completely wrong and my research is based on the limited publicly available data, so I'm sure to be missing the full picture.
@UpsideDownFork who knows, it’ll be interesting to see. It’s funny - ten years ago if someone told me that one of my interests/hobbies/passions would be heat pumps, insulation and green energy, I’d never have believed them. I sure know how to bore people at parties now ;)
COP measurement details seem to be available on ALL the datasheets from the manufacturers I've looked at. My only gripe is the lack of support for installation of these units (A2A) given they are EXACTLY what the Government want us to do.
Thanks for commenting!
Unfortunately the lab testing for both A2W and A2A bears little resemblance to real world use.
I dont know if it was intentional or you've just missed it, but you didn't include one very important fact, at least for uk homes. The A2A also dehumidifies the air, so anybody with a mould isue should consider that.
That only happens when in cooling (or "dry" mode, which is just a nerfed cooling mode) - for heating it doesn't do any dehumidification.
What Ben said.
Also, in my own isolated (so anecdotal) experience. Our A2W heat pump has reduced our humidity level in the house as well as reducing condensation on windows and mould growth.
The constant heating ensures we have no cold spots and less opportunity for moisture to condense on cold surfaces but I can't entirely explain how the moisture level has reduced. Perhaps it's something to do with less convection currents and less opportunity to draw cold moist air into the house from outside. I really don't know but we have dropped humidity level by nearly 10% as an average by switching from our old gas boiler with on/off controls to a weather compensated heat pump.
The energy capacity of ground, water is much, much higher than the energy capacity of air.
The best one, the only heat-pump that I can recommend buying is the 3th option: groundwater or ocean-water to water.
They cost a lot more, you need to dig into the ground, or lay pipes into the ocean, but they have a reliable heat-source in the cold winter months.
Thanks for commenting.
A significant capital difference for a small efficiency benefit.
A2A is nice, but often runs into the problem, that the internal Temp sensor is inside the unit. That means it will often turn itself off very quickly and do a lot of on/off cycles without properly heating the room.
If you want it to actually work as a heating system then you need to get an A2A that has a sensibly placed temp probe or you need to modify it.
Additionally, if you aren't going with a ducted system, then you will need several units if you want any kind of evenly heated home and that can get expensive, especially if you have to have all those units serviced regularly as well.
For cooling, I have one centrally mounted A2A unit that manages to keep the entire house at bearable levels in summer. For heating I went with an A2W System since we have underfloor heating and that is a much more comfortable and natural way of staying warm in Winter.
I've not run into that issue with any of the units I've had. My Toshibas seem to manage just fine with the probe in the unit. With my Hitachi, the temperature sensor is in the remote. So I've started to place the remote further away to use the temperature of the adjacent room to the unit rather than the room the unit is in.
Thanks for commenting!
Would of thought Air 2 air is more beneficial to people living in flats and maisonette type of property
It can be in some cases.
I've had an ASHP for 14 years and solar for 13 years. I have a 5 bedroom house. The unit is 12kw. I have some underfloor heating and large radiators. I have tried running it continuously but it does seem to cycle frequently and cost more to run. I think the attitude then was that you needed a large unit to ensure that it will be adequate. There is no way to get any data about its efficiency. I have only had one service in all that time and realise that I really need to sort that out. Overall I have been happy with the system but have thought about replacing it for a more modern unit. Obviously there would be no grant so the cost of just replacing the heatpump would be high. I have decided to install ATA in 4 rooms. This is going to cost a similar amount. I like the idea of cooling in the summer, especially in those hot nights when sleeping. I am not sure if this makes real financial sense but this that isn't really an issue. For most people cost is the important factor and if there was no grant on ASHP I suspect most people would go for ATA as I believe they do in a large part of the world. I hope I can use the systems to compliment each other.
Thanks for commenting!
Hopefully VRF systems will get cheaper and smaller, then you can do air to air and air to water via the same outdoor unit.
That way you could cool your rooms and use that heat to heat your hot water.
We have air to air as we removed storage heaters and had no existing plumbing.
But I think the best combination is underfloor heating and ducted air to air.
That way you can do the ground floor with a big underfloor heating setup, and then do the upstairs via air.
I think it’s unlikely that systems capable of simultaneously cooling and heating (e.g., heating water using the heat extracted from cooling) will become common in residential heat pumps. The added complexity often outweighs the benefits for small-scale applications. However, it makes a lot of sense in larger setups like hotels, where there’s a constant demand for both hot water and air conditioning.
For my A2A system, it also provides DHW. When the system switches to heating water, the cooling function temporarily pauses. Once the hot water cycle is complete, the cooling resumes.
There’s already some heat reuse happening in these systems. For example, when cooling, the outside coil heats up. Some of this heat is diverted to assist in heating water. Similarly, after heating water, the system starts cooling from a slightly lower baseline temperature, which can make cooling more efficient.
Thanks for commenting!
A2A is far more efficient and has a longer life than A2W. Historically, A2W has required a multi-stage solution, or two or more compressors and heat exchangers to achieve the required temperature increase for hydronic heating. This provides a useful indication of how much harder a heat pump has to work when used to heat water compared with conventional A2A heat pumps. This means that the compressor, which is the most expensive component, will need to be replaced much sooner and therefore significantly increases the long-term running costs of the heat pump.
It would be very interesting to see a video comparing the reliability and repair costs of the different heating technologies even if it was, for example, a comparison of present day costs for key components for each system, the availability and likely cost of the actual repair. Such an insight would be very eye-opening and in some cases eye-watering.
Personally, my own choice would be air-to-air as I like rapid response and the efficiency is much better. On the other hand, there is already gas central heating installed so air-to-water is potentially a simpler option. Considering the property, a multi-drop mini-split system would likely be an easier install than a fully ducted system.
The fancoils of A2A systems actively moving air eliminates stratification in the room which ensures an even temperature and adds to the overall comfort. This stratification, makes A2W systems even even less efficient unless something is done to mitigate this such as a ceiling fan or using hot water fancoils rather than passive radiators.
As far as noise is concerned, a fancoil unit can be very quiet on low speed and can be quieter than even an electric fan heater. Also the sense of a gentle air movement can be very pleasant.
On a personal note, I am autistic and have sensitivities to sound and light amongst a whole host of other issues. In my own experience I have found it a lot easier to tolerate the sound of a fan and moving air from even commercial heat pump systems, presumably as it is a smooth and continuous sound. I find the noises from hydronic heating to be less tolerable and the random sounds quite disturbing, especially first thing in the morning when I am generally most sensitive.
This is not true. Historical or industrial comparisons bear no relation to a domestic A2W heat pump in 2024.
Most A2W systems run a flow temp between 25-45 degrees with weather compensation.
It's currently 6 degrees outside and my A2W system is running a flow temp of 33 degrees.
A single stage compressor with R290 refrigerant can achieve flow temps of up to 75 degrees.
A weather compensated system runs so low and slow. It produces a very gentle constant heat that builds up thermal mass.
Convection is not as comfortable as thermal mass.
I have just had a quote for a2w from a heat geek which was £13k with a grant included. Circa £21k for a heating system!
@@kevindruce8915 wowsers! Have you had any other quotes yet?
@ not yet. I am still on the floor. I know the gas boiler is wrong but it’s working well for my 5 bedroom house. So I’m struggling to justify it going. The quoted for 10 kw valiant.
Sorry I want to be positive as I know ethically it is the right thing to do.
I do enjoy the content they put out on their channel, and it seems they know their stuff and can get the best out of what heat pumps can offer, but you're far from the first that has been quoted exhorbitant prices from a Heat Geek installer. Given that all installers doing work for the BUS have to be accredited anyway, there's something going wrong somewhere; to get the MCS accreditation installers should have to guarantee a SCOP in the same way that Heat Geeks do.
The prices quoted for any installation, when you look at the purchase price of the parts, is high enough already; like any government scheme that offers free money as long as work is done by an "accredited company" (whether this is double glazing, insulation, heat pumps, solar etc), the grant simply inflates the prices the "accredited companies" charge and there's little benefit to consumer and simply an increased profit for the installer.
I appreciate that the current BUS grant is actually very generous, but can't help feeling that it's still (in part at least) inflating the cost of installations especially as it's still insisting on work being carried out by a limited number of approved installers who still don't offer the guarantees that the exhorbitantly priced Heat Geeks do.
For us we’re mixing the two, air to water downstairs (underfloor heating) and hot water, upstairs air to air, as we will get cooling as well, and we can get rid of every radiator in the house.
However part of the decision was based on the fact the grant doesn’t cover air to air systems because it cools too and often doesn’t do hot water and saving £7500 seems like a no brainer.
If it wasn’t for the grant we’d probably not bother with a2w, as it’s heating only and extremely expensive.
Thanks for commenting!
The fact there is no grant available for air 2 air raises big questions about what is actually trying to be achieved with regards to moving away from gas.
Much like why people can have cheaper electricity to charge an EV with off-peak electricity, than people heating their homes and water with off-peak electricity.
Something isn't quite right about all this, and government thrive in division!
Thanks for commenting!
@BROOMEngineeringTMIET I have wondered that myself. Don't know if it's baseless but as A2A is so cheap to run maybe like solar there's the "whats in it for me?" equation. Reducing the power you use reduces the profits. Why else did they stop any aid for solar?
You can get nice looking units or if your having a new build then, then the ducting is ran in ceiling cavity and no room units are required.
The units them selves are not audible, unless you have them on really high fan speed and its not really required if you use them correctly.
Air conditioning on the other hand does dry you out in summer.
You can just get a hot water cylinder with immersion heater if required and heat the water in off peak and boost it if required in peak, it's not really expensive unless you have a massive hot water demand and the price difference between a hot water cylinder immersion vs heat pump cylinder is quite significant and would take a rather long time to recoup the price difference and also will require larger wholes with the heat pump version in walls.
If it was a new build air to air, if retro fitting where you already have the pipe work and rads then air to water makes more sense. ( Unless you want air-conditioning or are in a small home where one or two units can easily heat the whole home)
Thanks for commenting!
@UpsideDownFork thank you for the video
Very good. Oil is a bit worse than gas, not by much and it is less convenient, storage, non-combi, emissions,.... We need to campaign and rise up against any form of on demand electrical heating!
Thanks for commenting!
Air to air can be more efficient with on average +1 on COP as air to air works around 30-35C while air to water is usually run at 55C. This means the heat gradient for the pump is less for air to air allowing COP of >5 where a air to water is around 4.
This is not true. Most A2W systems run a flow temp between 25-45 degrees with weather compensation. It's currently 6 degrees outside and my A2W system is running a flow temp of 33 degrees.
@UpsideDownFork ok
@UpsideDownFork so the water in your radiators is only about 30c
@tomooo2637 plenty enough to warm a room to 21 degrees 👍
water to air. water source like lake or pond will provide a more stable and effective heat cooling sink.
Thanks for commenting!
If your home isn't connected to gas and you already use electric heating then air to air is an easier choice to make.
If you don't have much room it could be the only choice unless you want to stick with resistive electric heating.
Thanks for commenting
So many heat pump advocates suggest heating the whole house for lots of the time, ive never understood how this can be cheaper than heating just the rooms that are used.
@@South3600 a house has a heat loss. Over a 24hr period it will lose a certain amount of energy.
It doesn't really matter if you put that heat energy back into the property gently over 24 hours or intensely over 4 hours. You are still replacing the same amount of heat energy that is lost.
The main difference being that appliances don't work as hard when this do this job slow and gently.
This is true for gas boiler and heat pumps alike.
Why not combine them?
@@manzourahmed3383 fine if you have the capital to invest.
@@UpsideDownFork No, I mean in the heat pump, i.e. two heat-exchangers, one for water and one for air.
I've an A2W system in my house, and it works great. I agree about the tribalism, and we should be focusing on just moving off gas boilers. However, electric boilers and IR panels have their place too. They are still electric at the end of the day and lower carbon than gas boilers.
I've an electric boiler in a flat that I rent out as the gas boiler was leaking water from the flue and dripping through the ceiling. Rather than trying to fix the flue by ripping the ceiling out, an electric boiler made the flue redundant. Hanging a heat pump off the balcony or external wall is not really an option. The building management company would have something to say about that!
Thanks for commenting!
we switched from an oil burner to air to air and i am more then happy. the wormth is better the air does not feel so dry, with the radiators i always had to run a fan to move the air ~ literally to stop having a hot head, wished for temerature at the butt and cold feet. if you have in floor heating this is not a probleme but most older homes don't have that. i am not going back to radiators. in the past with the really old oil heating it worked but the temerature of the radiators was more in line of 75°c to 85°c then they radiate heat not only warm air. but you have to explain a child not to touch these burning hot peaces of metal conviniently accesseble for small hands...
one thing you can't do is turning your air to air system off. this will bite you. just let it run like you would with normal heating then everything is nice.
@@SteffenF thanks for commenting 👍
Your presentation assumes the listener knows how these two systems basically function. A brief explanation at the start would be really helpful.
Thanks for the feedback!
You forgot to mention that A2A costs less, but on the longer run, A2W wins as it can work during the night when the electricity is 4x cheaper. Besides, I cant sleep while AC is heating, its noisy and dries out the air. A2W is much convenient. I know some people who made A2W from A2A AC units. Thats the perfection of both worlds and it works great. For 1500$ investment you can heat the whole house 100m2 or more.
For us in the UK, A2W quite often works out cheaper because of a government subsidy that is currently in place.
There is so many factors missing… maintenance and cleaning(especially a2a), defrost algorithms and their effectiveness… if you recently insulated the house and had radiator heating, they got oversized for current lower heat loss. This is perfect for a2w ad it allows you to heat with lower temp (lower temp difference increases cop). Additionally a2a are primarily designed for cooling, heating is just an addon. A2w the opposite, therefore built in cop stats and mostly a huge number of efficient defrost algorithms! At low outside temp a2w clearly wins.
Thanks for commenting
Air to air is more efficient than air to water. Air to air temperature it has to produce is lower than air to water by a lot.
Not strictly true. A2W systems, especially with large radiators or underfloor heating, have a much larger surface area for distributing heat, allowing them to run at lower temperatures - even compared to A2A units.
Thanks for commenting!
Heating with water and especially in floor heating is more efficient on the heating side. Also people tend to ramp up the temperature in air heated rooms because it’s less comfortable and that in turn gives a higher need for energy as well.
We went down from 20c to 18,5c when we had the water temperature go down from 60c to 30c just because the lower temperature of the radiators moved less air. At work I need 21c to feel just as nice as 18,5c at home and at work we have air to air. And the noise of the airconditioning unit keeps being annoying to me.
Difficult to say if it's always more efficient in-situ as the data and monitoring isn't there...
@@BenIsInSweden ac set to hest a home to 20C can shoot warm air at 22-23C.
If you wanna do it with water unless your whole wall is a giant radiator, it will be at least high 30s.
It is simple. If you can afford it, get air-to-water. If not, get air-to-air. Simple as that.
Thanks for commenting.
If only life was that simple!
A2W worked out considerably cheaper for us in our house 👍
Is dehumidify with A2A a missing benefit? E.G. for a damp flat (fix the source too of course).
I have...
A2A in my garden office, which is brilliant: 40°C air almost instantly, cools in summer, daytime use is free with spare solar (400w even on a cloudy day on a standard 4kWhp E/S panels setup). The Mitsubishi wall unit is right by my head, but no noisier than the laptop fan.
A2W (Octopus installed) for the 4 bed detached mid-90s home. £3k after grant. Even warmth throughout; no drafts.
Fridge & and freezer: A2W presumably?
Nissan Leaf: A2A cabin heater
Pool heater: £500 portable A2W, free on spare solar, zero install costs.
My point is it's horses for courses! 💨💦🎠🐎
Great points!
Just installed a A2W heat pump and I am so happy to turn off the A2A pump! Why? Because I absolutely hate the sound of that fan blowing, the overheating on some area to get the heat to areas far away and also the uneven heat as the pump de-frosts. And yes, my ”old” A2A pump was from 2021 and of a good brand (Fujitsu KM12 slim) so Im not comparing A2W with a lousy A2A pump. Will still use it in the summer and if I need extra heat (so far not needed even though we have had -10c).
Thanks for sharing your experience!
We should to fitting water source heat pumps, we live a island for god sake
I am surprised we don't see more of them in the UK. Apparently more common in continental Europe.
But what about water to water?
Too niche for me to cover in this video.
Thanks for commenting!
I don't just like hot air being blown around for heating, makes the breathing of it yucky
If you run it constantly you do get a little bit of that, but it runs in a very similar way to a2w, it just constantly circulates the air, we have 2 rooms we’ve installed air con into and the temperature in both is within a degree of the desired temperature constantly. If you treat it like a boiler you do get the hot air being pushed around, if you leave it on it just trickles heat in and only occasionally ramps up, if say someone lets a load of cooler air in or you change the set temperature.
You can adjust the louvers so it doesn't blow on you. The air is also filtered and some have air purification systems to remove things like allergens and viruses
Thanks for commenting!
Curious when you mentioned about coming in the future hot water with ATA ? is a video pending with explanation? I know there’s no grant with ATA but if any governments priority is to get rid of gas boilers hopefully someone with common sense will take a different approach, I know there’s targets within the industry in regards to heat pump uptake by customers set by government , pity there wasn’t some kind of survey done in regards to ATA so the industry can prove too any government that if you were to include ATA within the grant scheme this would increase the uptake on getting rid of gas boilers hopefully, are you aware that there are also wall mounted radiator type ATA units so they are not all that are near the ceiling type keeping the top of your head warm but warm air from the ground up which are much better in my opinion, maybe the best video I have ever seen in regards too ATA which I saw last week and it was a year old video I think anyone who would watch it would never get ATW , I would get rid of my gas boiler tomorrow if a grant was available for ATA .
The reason ATA isn’t supported by government is the UK power network does the majority of planned maintenance during summer and therefore they are opposed to the increase cooling load during summer
@@ruperttodd8639 I’ve heard this so called argument before , it’s a very weak argument , really come on we are talking about here in the UK not Florida, how many days if any would we need the cooling element of ATA system one day maybe two if we’re lucky , sorry that doesn’t add up at all , if anyone in any government were given the statistics of getting rid of gas boilers with the inclusion of ATA within the grant scheme as with ATW then the use of gas boilers would probably be obtained within three years and not twenty years plus with only ATW on the scheme , it’s so obvious even my cat understands, the system at the moment makes no sense at all , it would be easier trying to explain Norway to a dog .
Thanks for commenting!
@@UpsideDownFork are you sure ?
Excuse me but what’s wrong with Infrared heating? I hear Herschel panels are good 🤣😋
(That’s a dig at them not you!)
😂😜😁
Air-to-air is fine but the systems have a limited lifespan, try replacing just an indoor cassette in 10 years time, you’ll end up having to rip it all out in many cases. This is why it shouldn’t have government money going into it beyond the VAT relief.
Thanks for commenting.
Every one is different every situation is different 👍👍👍
Thanks for commenting!
woodburners win the war
🙂😜😁
Wood burning stove in each room is best.
@@cloudyskies1323 best for generating PM2.5 inside the home and best for increasing your risk of carbon monoxide poisoning due to dirty flues. 👍
Air to air is like a dry heat that might make people cough and be a dry heat. And the fact it doesn't do water. That's a biggggg reason, and needed 12 months a year
Thanks for commenting!
A2A systems don’t produce 'dry heat'; they simply provide heat, much like a central wet system. The dryness people notice often comes from the ambient conditions in winter, not the heating system itself. For example, Tim and Nigel (EV Puzzle) both use A2A systems and still run dehumidifiers in winter, highlighting that A2A isn't inherently drying.
Personally, I use a humidifier to maintain comfortable humidity levels, which is something you'd need regardless of the heating system. Also, some A2A systems can handle water heating (I have one - a Hitachi Yutampo Twin), they are slow to enter the UK market though, but I believe the Daikin Multi+ one is available.
BTW no heat pump is better than a correctly fitted and already-working gas heater system (in terms of cost and convenience).
Actually it's the reverse, a gas boiler will beat a heat pump in poorly set up systems.
The closer you get to running a boiler at maximum efficiency the more a heat pump will run away in terms of efficiency so it will always be cheaper to run.
Convenience also comes at a cost, i.e. "instant" hot water will always be more costly for daily showers/baths compared to having a hot water cylinder heated by a heat pump.
We could debate this all day.
Recently in the UK there were large parts that experienced power cuts. Many of these people were left with no hot water. Those with hot water storage cylinders (all A2W heat pump owners) did not experience the inconvenience in the same way as those with combi boilers did.
Also...most gas boilers are not "correctly fitted" by my definition. Flow temp too high, no consideration of modulation or any compensation controls. 10-15% thrown away by poor setup.
@@BenIsInSweden Here in the UK the cost differential between gas and electricity is such that there is little advantage (economically) in favour of running a heat pump. When you factor in the astronomical cost for many (most) properties in the UK that require upgrading in terms of insulation etc and the larger radiators etc that cost is often unrecoverable over the stated lifetime of the A2W heat pump system. As it stands, electricity cost is only headed in one direction - upwards. Gas/oil is not increasing by the same proportion.
@@UpsideDownFork Sad that people are being constricted economically by poor installation practices. That said, I can point to a local A2W installation where the client was taken advantage of (elderly lady trying to 'do the right thing' and sold a pup). Disgraceful practice and certainly not helping change minds.
@@kellyeye7224 yep, that I can definitely agree on.
ECO4 is leading the charge when it comes to heat pumps getting a bad reputation. 😭