Heating and cooling: How to choose an air source heat pump

61 to 90 of 155

- CommentAuthorDiarmid
- CommentTimeFeb 8th 2021
Thanks for your responses...green issues are in my thoughts obviously but not at any cost.

The house is well insulated <5 years old, a rubble stone converted farm building with additions Single storied. It's south facing and sits about 550ft - very exposed to the SW, in West Central Scotland. We've got triple glazing. This is a second home but we plan to retire here in a year or so's time. My estimation for energy use is a guesstimate based on the consumption now (we're here most weekends). We have a wood burner too. Water is heated by LPG. Shower only no bath. Electric hob.

I am minded to include some PV on the south facing roof, to run an air pump on the sewage system (80W) but runs 24/7 and put the rest to heating water. I've no idea of costs really but ASHP or GSHP + PV might be a good investment of my retirement fund given the poor return on savings/investments etc.
- CommentAuthorowlman
- CommentTimeFeb 8th 2021
I my case when I looked at good quality appropriately large sized A2W heat pumps they were somewhere between
£ 8-10K plus fitting additions etc, and if I'd gone down the split route there's the "F" gas fitter fees. I imagined waving goodbye to £12K +, hence my current number crunching exercise.
- CommentAuthorEd Davies
- CommentTimeFeb 8th 2021
Posted By: Diarmid…PV might be a good investment of my retirement fund given the poor return on savings/investments etc
Indeed, I'd say they're one of the few index-linked pensions most of us can buy.
- CommentAuthordjh
- CommentTimeFeb 8th 2021
Posted By: Ed DaviesIndeed, I'd say they're one of the few index-linked pensions most of us can buy.

The state pension is the bargain of this or last century. Definitely pay that to the max.
- CommentAuthorWillInAberdeen
- CommentTimeFeb 8th 2021 edited
How is PV "index linked"? FITs have long since ended.The price of electricity can go up as well as down.

When I looked it would cost £4k to install panels to generate 4000kWh/a which currently pays 5p/kWh, so £200/a. So it takes 20 years even to recover the cost of the panels and break even, nevermind make any return on the investment, and that's if the inverter lasts that long and you don't move house. If PV were a goldmine then there would be a goldrush of goldminers, but I haven't seen that for last few years...

State pension is a bargain for the generation claiming it, possibly less so for the generation who are paying for it with not much prospect of getting it themselves, but let's not get too political on GBF 🙂

I advise everyone not to take investment advice from my comments on this internet forum, or any other...
- CommentAuthorDiarmid
- CommentTimeFeb 8th 2021
Seems I've opened a can of worms apologies.
- CommentAuthorJeff B
- CommentTimeFeb 8th 2021
Posted By: Ed Davies
Posted By: Diarmid…PV might be a good investment of my retirement fund given the poor return on savings/investments etc
Indeed, I'd say they're one of the few index-linked pensions most of us can buy.

I'd say it WAS one of the few index-linked pensions most of us can buy but not any more for the reason WillinAberdeen has stated. I was one who was lucky enough to have enough savings to invest in PV solar at the very beginning of the FIT scheme (2011). It currently pays 55p per kWh and our system generates approx 3100 kWh p.a. However my system (4.2kWp) cost a hefty £16,000 (21 x 180W panels and 21 x microinverters), so the system has not quite paid for itself yet - another year or so I think. The next 14 years or so will see a return on the investment, assuming I'm still alive and kicking by the end of that period! If we sell up in the meantime and downsize then the next occupant will reap the benefit. Hopefully that may be an additional selling point for the property. As I understand it at the moment it doesn't make a ha'pence of difference to potential house buyers. But then most people are only interested in the size of the kitchen and whether there is a hot tub on the patio!
- CommentAuthorWillInAberdeen
- CommentTimeFeb 8th 2021
No worries Diarmid!

If your house does consume about 16000kWh each year as Ed worked out, and if the price for LPG remains 7p/kWh and for ASHP heat is 5p/kWh (midpoint of figures above) then you can save 2p x 16000kWh over seven years*= £2,000

Plus RHI of 10.85p x 16000kWh for seven years = £12,000

So you could get some quotes and see whether a ASHP costs no more than £14,000 more than a new LPG boiler. Remember to include for a hot water cylinder and bigger radiators or UFH if you need them.

Then factor it against your other investment opportunities! 🙂 Good luck,

*Seven years is the lifetime of the RHI
- CommentAuthorEd Davies
- CommentTimeFeb 9th 2021
Posted By: WillInAberdeenHow is PV "index linked"?
Because you still have energy, even if there's hyper inflation. Nothing to do with the FiTs.
- CommentAuthordereke
- CommentTimeFeb 9th 2021
Posted By: Jeff BIf we sell up in the meantime and downsize then the next occupant will reap the benefit.

I was lucky enough to buy a house that had solar installed on the original FiT. The payments pay for all our electricity usage and that is with an ASHP (non RHI) and electric car. The solar wasn't the selling point but it was definitely appreciated.

ASHPs can be installed quite economically, you just have to forgo the RHI and manage the project.
- CommentAuthorWillInAberdeen
- CommentTimeFeb 9th 2021 edited
Posted By: Ed Davies
Posted By: WillInAberdeenHow is PV "index linked"?
Because you still have energy, even if there's hyper inflation. Nothing to do with the FiTs.
But that's not index linked? If the price of off-peak energy continues to fall in the future or frequently goes negative, then an investment in PV was a big waste of money....?

Whereas if you had FITs, they'd keep on paying in real terms, irrespective of electricity prices or RPI, so your investment is more certain to pay back.

It would be 'index linked' if what you pay for energy varies in proportion to an index, such as RPI/CPI, ideally the same index that your pension is linked to, if you have one. You can do this if energy forms the same proportion of your spending as it does of the inflation 'basket' - so don't own a house or car that imports a lot more energy than everyone else, or a lot less.

Edit to add: we recently sold a house, rented a house and then bought a house, and energy efficiency made not a jot of difference to any of the prices
- CommentAuthorEd Davies
- CommentTimeFeb 9th 2021
Posted By: WillInAberdeenBut that's not index linked? If the price of off-peak energy continues to fall in the future or frequently goes negative, then an investment in PV was a big waste of money....?
My original comment was some tongue in cheek so let's not get too technical but the point is that the value of PV is linked to price of energy. Fair enough, if energy prices go down then their value goes down. How many think that's likely long term and overall (not just for periods of a few hours now and then until the energy system adjusts to the amount of renewables)?
- CommentAuthorphiledge
- CommentTimeFeb 9th 2021
With a significant migration to electric power where that power can be consumed off peak, I cant see the low off peak rates lasting more than a few years. I certainly wouldnt be personally planning any power usage schemes based on cheap off peak rates.
- CommentAuthorWillInAberdeen
- CommentTimeFeb 9th 2021
Yes, it's a bit of a gamble!
If you bet that off-peak prices will get higher, then buy solar PV.
If you bet that off-peak prices will get lower, then buy a big thermal store and an electric car.

If like me you'd rather not gamble with your pension then buy dereke's house with FITs! Or buy an ashp and claim RHI. Both are index linked.

We discussed a few times recently that people will not build enough storage unless off-peak prices stay low, and if not enough storage is built then off-peak prices will get lower. I think they'll get lower, but I wouldn't bet on it.
- CommentAuthortopher
- CommentTimeMar 26th 2021
You may find this interesting. . . .

A neighbour has installed an air/air system using separate units in each room. The two fan units in the garden feed refrigerant to units in nearly all rooms in the house. It can heat or cool. Not applicable for the government grant, and no means of producing domestic hot water.

I think it has these advantages
1. Cheaper to install.
2. Much higher efficiency as the temperature difference from outside (say 5 deg) to inside (say 20 deg) is much lower than radiators which need say 60 deg
3. Will cool or heat
4. Simple to control
5. Existing system can be back up
- CommentAuthorJeff B
- CommentTimeMar 26th 2021
Posted By: topherYou may find this interesting. . . .

A neighbour has installed an air/air system using separate units in each room. The two fan units in the garden feed refrigerant to units in nearly all rooms in the house. It can heat or cool. Not applicable for the government grant, and no means of producing domestic hot water.

I think it has these advantages
1. Cheaper to install.
2. Much higher efficiency as the temperature difference from outside (say 5 deg) to inside (say 20 deg) is much lower than radiators which need say 60 deg
3. Will cool or heat
4. Simple to control
5. Existing system can be back up

Do you know what make he/she went for, how many units and the cost?

I was quoted £4800 for a Panasonic split system with 3 internal units and one external unit. Having seen the cost of the kit on the Internet I think that is hugely expensive so didn't go for it.
- CommentAuthorEd Davies
- CommentTimeMar 27th 2021
Posted By: topherA neighbour has installed an air/air system using separate units in each room.
Yes, good plan. There are quite a few low-energy house in the New England which use mini-splits like this. Typically they have two for the whole house, not because they need that much heating but rather to get better heat distribution (and also redundancy and maybe quicker warm up). That's what I suggested to some friends who wanted to build an on-electricity-grid but off-gas-grid house on a north-facing slope in some woodland.

But …

2. Much higher efficiency as the temperature difference from outside (say 5 deg) to inside (say 20 deg) is much lower than radiators which need say 60 deg
seems like a bit of an overstatement. Typically you run heat-pump systems nearly continuously so a lower temperature even for conventional-sized radiators, let alone UFH, is appropriate.
- CommentAuthorWillInAberdeen
- CommentTimeMar 27th 2021 edited
Need to include the extra temperature differences because the refrigerant must get colder than outside air to absorb heat, and warmer than the CH water to release heat

Eg if outside is 5degC

Air-Water heat pump heats refrigerant from 0degC to 45degC, refrigerant heats CH water to 35 degC, UFH heats house to 20 degC

Whereas Air-Air heat pump heats refrigerant from 0degC to 30degC, refrigerant heats house to 20 degC

So A-W is heating its refrigerant by 45/30 = 1.5x as much as A-A.

The Air-Air indoor units are quite expensive and are based on aircon design for cooling with fan convection. Im looking out for when someone makes a coil of refrigerant pipe that can be set into a floor and used as air-air UFH. Best of both worlds?!

Has anyone experience of an air-air indoor unit in a bedroom? Noisy?
- CommentAuthordjh
- CommentTimeMar 27th 2021
Posted By: WillInAberdeenHas anyone experience of an air-air indoor unit in a bedroom? Noisy?

All our relatives in the far east have them. Bedrooms are the first rooms that get A/C. Not particularly noisy these days (they used to be in the days of through-window monoblocs!) but can be quite difficult to adjust the temperature setting. It's all too common to see people with duvets in a tropical bedroom because it's too hot if switched off, and too cold if it's on. It seems to be difficult to get something that can maintain a draft-free even temperature given a control setting. Maybe if the houses were better insulated so required smaller power heating/cooling it would work better? Dunno.
- CommentAuthorowlman
- CommentTimeMar 27th 2021 edited
@ jeffB
£ 4800; That's £ 4000 net. A Panasonic R32 inverter, 3 multi split could come in at over £2000 net, more if you opt for designer indoor units.
Additional costs could include a separate feed and breaker to the CU plus all the necessary isolators etc at the outdoor unit. Then there's the refrigerant pipework, insulation, and trunking to three indoor units plus condensate drains and mini pumps plus delivery. At cost prices that lot could easily come in at over £600.
Just assuming an overall material bill of £2600, your fitter/s are charging about £1400 for possibly 2 men for 2 days or at least 2-3 visits incl. survey.
That doesn't appear to leave a huge profit margin for the "F" gas qualified fitter with all his overheads.
- CommentAuthorowlman
- CommentTimeMar 27th 2021
<blockquote><cite>Posted By: WillInAberdeen</cite>
Has anyone experience of an air-air indoor unit in a bedroom? Noisy?</blockquote>

I've been running my A2A since Autumn of 2019. I'm over the moon with its reaction time, and efficiency. So much so that I'm now planning a second install this Summer with 2 small 3.5 - 4 kW indoor units both with their own outdoor units. The indoor units are both rated at 19dB on low power, they modulate of their own accord. There is also the condensate pump to consider. That can be remoted but even if located nearby the "silent " rated ones are almost that, plus they don't run all the time, only when the internal reservoir is full.
I'm a total convert to A2A, I think A2W with UFH is an expensive overcomplication for space heating. The perceived additional benefit of DHW is better dealt with by a separate Immersion if you need stored HW, or better still point of use instantaneous if building from scratch.
Were I building new, something less than Passivhaus, I'd incorporate a ducted system, quite easy at the build stage.
The simplicity and cost of A2A, not to mention its efficiency, plus occasional Summer cooling, plus air filtration are winners.
- CommentAuthorJeff B
- CommentTimeMar 27th 2021 edited
Posted By: owlman@ jeffB
£ 4800; That's £ 4000 net. A Panasonic R32 inverter, 3 multi split could come in at over £2000 net, more if you opt for designer indoor units.
Additional costs could include a separate feed and breaker to the CU plus all the necessary isolators etc at the outdoor unit. Then there's the refrigerant pipework, insulation, and trunking to three indoor units plus condensate drains and mini pumps plus delivery. At cost prices that lot could easily come in at over £600.
Just assuming an overall material bill of £2600, your fitter/s are charging about £1400 for possibly 2 men for 2 days or at least 2-3 visits incl. survey.
That doesn't appear to leave a huge profit margin for the "F" gas qualified fitter with all his overheads.

Owlman - thanks for your response. I'd be interested to know what the OP Topher's neighbour paid for his system. The quote I had does not include the electricity supply from the CU, that's down to me to arrange separately so this would be on top of the £4800 but hopefully not too expensive. Is it a case of being held to ransom to some extent because of the need for an F gas qualified fitter? Also the three indoor units would only be a partial solution as they only cover one half of the dormer bungalow, the rear half! (Kitchen/diner, lounge and landing). To supply the other half would be a logistical nightmare. I think I would need a second outdoor unit near the front of the property - this would be unaffordable.

IIRC you have a similar issue with your property effectively split into two. Will you have any issues with permitted development if you have more than one outdoor unit? In Wales I am only allowed one within permitted development, any more will require planning permission.
- CommentAuthorShevek
- CommentTimeMar 28th 2021 edited
Has anybody had any experience with Dimplex's heat pump cylinder Edel?

https://www.dimplex.co.uk/product/edel-hot-water-heat-pump
https://www.dimplex.co.uk/product/edel-hot-water-heat-pump-rf

I'm considering retrofitting one of these into an apartment.
- CommentAuthortopher
- CommentTimeMay 25th 2021
I would be interested in your comments on the following. . . .

* I have found what I believe is a good installer.
*Looking at the SCOP of different manufacturers at 55 degrees, Daikin comes out well
* The Daikin model 3 H HT (split, 70 deg output) looks good, but the lowest output is 14 kW. My gas boiler is tweaked down to 15 kW. This output is well able to achieve the ambient of 19 degrees. What are the problems if the ASHP has too great an output?
- CommentAuthorWillInAberdeen
- CommentTimeMay 26th 2021
Hi Topher, that's a good plan.

My comments on page 1 of this thread about a previous Daikin HT heatpump still apply, including the bit about ours working well despite being deliberately oversized.

The new HT model you identified is a very interesting proposition, it has a very good SCOP at 50+ degC so is perhaps the drop-in replacement for a 'condensing gas boiler' that people have been looking for...!

It seems to have two parallel outputs to run UFH and radiator circuits, and can also heat a DHW cylinder.
- CommentAuthortopher
- CommentTimeJun 1st 2021 edited
Hi Will, I have re-read your 1st post, and I think the current 3 H HT model is different. Basically it has two heat pumps in series and gives an output of of up to 70 degrees. So existing rads should be OK. Everything is in the outside unit except a 'hydro box' which is inside the house.

Edit on 8/9/2021. I was wrong. It is one single compressor using R32 which is able to provide 70 degrees. Apologies.

I am not sure what the hydro box does except electronics.

One new thing I learned is the outside unit has two anti frost valves. If you have power cut and it is cold the anti frost valves open when the internal pipe water is at +3 degrees. This is to protect the heat pump. If the residual pressure is above 1 bar, the pump will start again. If < 1 bar the pressure has to be raised before it will start

Regarding being oversized, my thoughts are that the pump will reach the set temperature faster so the likely problem will be short cycles, but maybe I have got this wrong.
- CommentAuthortopher
- CommentTimeJul 3rd 2021
Too late now if I have made the wrong decision.

I have chosen 12 kW Daikin 3 HHT. It can produce 70 degrees. One primary reason for the choice was my opinion of the installer. I hope the honeymoon lasts.

I am hoping to get about £770 per Q from the Government. If it happens, that will be nice.

Now I have to research different electricity tariffs. I wont have to pay the daily charge for gas either.
- CommentAuthortopher
- CommentTimeAug 25th 2021
Is anyone interested? Shall I keep going?

The installation starts next week
- CommentAuthorPeter_in_Hungary
- CommentTimeAug 25th 2021
Yes please, I'm contemplating ASHP so interested in others experiences.
- CommentAuthordjh
- CommentTimeAug 25th 2021
+1

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Heating and cooling: How to choose an air source heat pump