Air Source Heat Pump (ASHP)

[BullDog]

Air to air ASHPs are straightforward installations.
It's specifically the ones which heat water that need specific training.

You need to be licenced to touch anything on the refrigeration circuit of any appliance using refrigerant gas. Much like gas safe registration.

And you still need to be a competent plumber to start off with. And there are few enough of those.

Britain pretty much stopped training technicians (in all trades) in 1997 when Tony Blair decided we “needed” 50% of our population to be (sociology) graduates and turned all the Polytechnics into universities. “Modern apprenticeships” have scratched the surface of this problem, but there aren’t nearly enough of them to dent it.

So what politician is brave enough to reduce the highly profitable privatised university sector, and tell parents their little Tarquin isn’t bright enough?

Gryff

There's a few serious issues here. Firstly, all the better heating system plumbers I have come across are all sole traders and have zero interest in training an apprentice. Secondly, most of the demographic is well into their 50's and 60's and aren't interested in doing anything other than conventional gas heating systems. Thirdly, they're all fed up after a lifetime of work and want to retire and many are only looking after long time regular customers. Fourthly, the companies large enough to employ multiple staff and apprentices are often viewed as expensive and/or untrustworthy and only interestedin selling a new bolier when a slight problem happens. And of course, fifthly, nobody young wants to do anything beyond clicking a mouse, tapping on a keyboard or on a tablet. Not to mention the problem of greatly reduced East European workers.

I am lucky that I have a long time, over 35 years, trustworthy local heating bloke. Not everyone's so fortunate.

[DrFfybes]

There's a few serious issues here. Firstly, all the better heating system plumbers I have come across are all sole traders and have zero interest in training an apprentice. Secondly, most of the demographic is well into their 50's and 60's and aren't interested in doing anything other than conventional gas heating systems. Thirdly, they're all fed up after a lifetime of work and want to retire and many are only looking after long time regular customers. Fourthly, the companies large enough to employ multiple staff and apprentices are often viewed as expensive and/or untrustworthy and only interestedin selling a new bolier when a slight problem happens. And of course, fifthly, nobody young wants to do anything beyond clicking a mouse, tapping on a keyboard or on a tablet.

The consequence of this is the calibre of people gaining 'good' degrees. A modern 2.1 is often the equivalent of a 30 year old 2.2 at best. I had a PhD student come through who really wasn't up to the job, they passed, and I last saw them working in the car park barrier booth at a local bus station. Then a well respected colleagues student, who's thesis I read in an hour on the train feom Exeter to Plymouth, and found so many flaws, assumptions, and poorly substantiated assertions in that I sueegested another few months was required. hey passed a few weeks alter with some suggested amendments.

The thing is, if the quality of people gaining degrees is dropping like that, then the people applying for apprenticeships is dire. The chap who did our boiler had an apprentice, he seemed uncertain, unskilled, and lacking in any common sense or gumption. I asked had he been training long and he replied "18 months". He was sent for TRVs and drainoff valves for 3 new rads. He came back with 3 TRVs and one drain valve.

Paul

[funduffer]

I know this is an old thread, with most of the pros and cons of ASHPs described.

However, I am still left wondering what I would replace my gas boiler with if it broke down.

And now there is an energy crisis.

If I take the Ofgem price cap rates for October, they are 52p per kWh for electricity and 15p per kWh for gas. That is a ratio of about 3.5.

Now a modern ASHP has an SCOP of between 4.5 and 5. So by my reckoning that would make the running cost of heating cheaper with electricity compared to gas.(SCOP is the seasonally adjusted coefficient of performance: kW of heat out divided by electrical kW in). I assume the efficiency of the gas central heating system is pretty high, I have assumed 100%!

If electricity pricing regulations changed to take the much lower cost of renewables into account, then this would favour ASHPs even more. As it is, I have solar panels, so for air conditioning in the summer, or heating on sunny winter days, the cost for electricity would be lower still.

I have water filled radiators all around the house, but I just wonder what a system with wall mounted ASHPs in each room would look like as a new system, such as these from Daikin: https://www.daikin.co.uk/en_gb/product- ... multi.html

Am I barking up the wrong tree?

FD

[staffordian]

I know this is an old thread, with most of the pros and cons of ASHPs described.

However, I am still left wondering what I would replace my gas boiler with if it broke down.

And now there is an energy crisis.

If I take the Ofgem price cap rates for October, they are 52p per kWh for electricity and 15p per kWh for gas. That is a ratio of about 3.5.

Now a modern ASHP has an SCOP of between 4.5 and 5. So by my reckoning that would make the running cost of heating cheaper with electricity compared to gas.(SCOP is the seasonally adjusted coefficient of performance: kW of heat out divided by electrical kW in). I assume the efficiency of the gas central heating system is pretty high, I have assumed 100%!

If electricity pricing regulations changed to take the much lower cost of renewables into account, then this would favour ASHPs even more. As it is, I have solar panels, so for air conditioning in the summer, or heating on sunny winter days, the cost for electricity would be lower still.

I have water filled radiators all around the house, but I just wonder what a system with wall mounted ASHPs in each room would look like as a new system, such as these from Daikin: https://www.daikin.co.uk/en_gb/product- ... multi.html

Am I barking up the wrong tree?

FD

I too would be interested to hear the pros and cons of this type of system.

The ability to cool as well as heat must surely give it some advantage over the much vaunted air source heat pumps, though the need for a separate (and expensive?) provision for domestic hot water is presumably one of the cons.

I know a poster here has a Mitubishi split system with two interior units connected to one external unit and from memory is very happy with it, but I don't think it is a primary heating method, more a spring and autumn heater and a summer cooler.

[Mike4]

I know this is an old thread, with most of the pros and cons of ASHPs described.

However, I am still left wondering what I would replace my gas boiler with if it broke down.

And now there is an energy crisis.

If I take the Ofgem price cap rates for October, they are 52p per kWh for electricity and 15p per kWh for gas. That is a ratio of about 3.5.

Now a modern ASHP has an SCOP of between 4.5 and 5. So by my reckoning that would make the running cost of heating cheaper with electricity compared to gas.(SCOP is the seasonally adjusted coefficient of performance: kW of heat out divided by electrical kW in). I assume the efficiency of the gas central heating system is pretty high, I have assumed 100%!

If electricity pricing regulations changed to take the much lower cost of renewables into account, then this would favour ASHPs even more. As it is, I have solar panels, so for air conditioning in the summer, or heating on sunny winter days, the cost for electricity would be lower still.

I have water filled radiators all around the house, but I just wonder what a system with wall mounted ASHPs in each room would look like as a new system, such as these from Daikin: https://www.daikin.co.uk/en_gb/product- ... multi.html

Am I barking up the wrong tree?

FD

I too would be interested to hear the pros and cons of this type of system.

The ability to cool as well as heat must surely give it some advantage over the much vaunted air source heat pumps, though the need for a separate (and expensive?) provision for domestic hot water is presumably one of the cons.

I know a poster here has a Mitubishi split system with two interior units connected to one external unit and from memory is very happy with it, but I don't think it is a primary heating method, more a spring and autumn heater and a summer cooler.

Well the main thing you both seem to be overlooking is these air-to-air heat pumps don't give you any hot water. So how will you be getting hot water if you commit to these for central heating and scrap the gas boiler? Also, it seems you need planning permission for the outside heat collector and that may not be easy to get, given all the fears over noise pollution.

On the up side I think for heating they work very well but they need servicing, but when they break down there is no spares network available like there is for gas boilers. You'll have to employ the manufacturer's service department and they'll have you over a barrel when it comes to whether they actually fix it or declare "it all needs replacing, mate". so chose your brand VERY carefully.

I am considering getting one myself to find out first hand all the problems, if there are any. But I've yet to feel confident to dip my hand in my pocket....

[staffordian]

I know this is an old thread, with most of the pros and cons of ASHPs described.

However, I am still left wondering what I would replace my gas boiler with if it broke down.

And now there is an energy crisis.

If I take the Ofgem price cap rates for October, they are 52p per kWh for electricity and 15p per kWh for gas. That is a ratio of about 3.5.

Now a modern ASHP has an SCOP of between 4.5 and 5. So by my reckoning that would make the running cost of heating cheaper with electricity compared to gas.(SCOP is the seasonally adjusted coefficient of performance: kW of heat out divided by electrical kW in). I assume the efficiency of the gas central heating system is pretty high, I have assumed 100%!

If electricity pricing regulations changed to take the much lower cost of renewables into account, then this would favour ASHPs even more. As it is, I have solar panels, so for air conditioning in the summer, or heating on sunny winter days, the cost for electricity would be lower still.

I have water filled radiators all around the house, but I just wonder what a system with wall mounted ASHPs in each room would look like as a new system, such as these from Daikin: https://www.daikin.co.uk/en_gb/product- ... multi.html

Am I barking up the wrong tree?

FD

I too would be interested to hear the pros and cons of this type of system.

The ability to cool as well as heat must surely give it some advantage over the much vaunted air source heat pumps, though the need for a separate (and expensive?) provision for domestic hot water is presumably one of the cons.

I know a poster here has a Mitubishi split system with two interior units connected to one external unit and from memory is very happy with it, but I don't think it is a primary heating method, more a spring and autumn heater and a summer cooler.

Well the main thing you both seem to be overlooking is these air-to-air heat pumps don't give you any hot water. So how will you be getting hot water if you commit to these for central heating and scrap the gas boiler? Also, it seems you need planning permission for the outside heat collector and that may not be easy to get, given all the fears over noise pollution.

On the up side I think for heating they work very well but they need servicing, but when they break down there is no spares network available like there is for gas boilers. You'll have to employ the manufacturer's service department and they'll have you over a barrel when it comes to whether they actually fix it or declare "it all needs replacing, mate". so chose your brand VERY carefully.

I am considering getting one myself to find out first hand all the problems, if there are any. But I've yet to feel confident to dip my hand in my pocket....

You must have missed a bit

[funduffer]

On the hot water point, you are correct, that needs a solution. ASHPs don’t provide hot water.

I think I would go with a tank with an an immersion heater that soaks up excess solar power during the day, and cheap overnight electricity at night. As we both shower in the morning and otherwise only use small amounts during the day, I think this would probably be adequate.

I have an Octopus Go tariff, so overnight electricity is only 7.5p per kWh at night ( for 4 hours) currently - half the price of gas.

I just get the feeling that costs are going to swing in favour of electricity compared to gas, and ASHPs will become increasingly attractive, despite their initial high costs.

FD

[richlist]

We use our solar panels to heat our domestic hot water (set at 60 deg') and on average the system takes 2kw a day to maintain temperature. We often have to supplement the free solar water heating by using grid power in the depths of winter but for around 8 months a year hot water is totally free.

[DrFfybes]

We use our solar panels to heat our domestic hot water (set at 60 deg') and on average the system takes 2kw a day to maintain temperature. We often have to supplement the free solar water heating by using grid power in the depths of winter but for around 8 months a year hot water is totally free.

There's another thread going comparing gas and elec costs for heating water...

Is your 2kWh/day summer use, and is that for people or more?

I only ask a I never got an accurate figure for our elec, but I have for the gas at 8kWh/day.

Thanks

Paul

[PhaseThree]

We use our solar panels to heat our domestic hot water (set at 60 deg') and on average the system takes 2kw a day to maintain temperature. We often have to supplement the free solar water heating by using grid power in the depths of winter but for around 8 months a year hot water is totally free.

A good rule of thumb is that a 5 minute standard shower takes around 1kWh of energy.

(Assumptions being that a standard shower requires a water flow of 9 ltrs/min and that the water is raised through 20C)

[richlist]

I just thought it a good idea to give people some idea of what it takes in energy terms to maintain a 60deg tank of hot water every day. Obviously it can vary depending on how you use hot water, how many people etc. There are only 2 adults here. Hot water is mainly used for showers/ baths, we don't wash up, we use a dishwasher and 2kw is summer use but the tank is very well insulated so not much difference in winter.

[funduffer]

The newly published October 2022 price cap rates (in my area, Yorkshire) are 10.3p per kWh for electricity and 33.8p per kWh for gas (ignoring standing charges). That is a ratio of 3.28, and a heat pump should be at least 4 times more efficient than a gas boiler. So as far as I can see, it will be cheaper to produce a kW of heat using a heat pump than a gas boiler for the foreseeable future (at least the next 2 years). If market electricity prices are decoupled from gas prices, as is being proposed, then this gap will only widen with time. As I also have solar panels, this will further widen the difference.

Today I visited a Daikin Sustainable Home Centre (there are nearly 40 around the country) to talk to someone about the various options. (Worth a visit if you are interested in such things. They were very helpful and promote all types of heat pump and gas boilers, so are not biased one way or another.) I have a fairly new combi gas boiler that provides hot water and central heating, but following this summer, my wife wants some air conditioning for the hot summer days. So I am getting a quote for an air-to-air heat pump powering 2 air conditioning units - one for the living room and one for the bedroom. My plan is:

In the summer, I expect to use the units to cool these 2 rooms if required, using any excess solar power, which should make it a very cheap solution. I currently export a lot of excess solar in the summer, so I expect this will provide a lot of the power for the air conditioning.

In the winter, it should be cheaper to provide heat using the the two air conditioning units than the gas central heating, however, I will only get heat in 2 rooms. So I think I would use the central heating early in the morning to heat the whole house, and then use the air conditioning during the day to maintain the temperature in the living room, using any small amount of solar power available. I would probably boost the temperature of the whole house for a short while in the evening as well, and heat up the bedroom a bit with the air conditioning if it is really cold. A case of trial and error to get the optimum balance, I guess.

In Spring and Autumn, I may just heat the living room and bedroom using the air con, but it depends how cold the rest of the house gets!

The thing is, this solution is hedging my bets. I will have electric and gas heating solutions available to me, and hot water from the gas boiler. I think this could provide a medium term (maybe 10 years) solution until the gas boiler gives up, or gas boilers are banned, or the price of gas is no longer economic compared to electricity.

If anyone is interested, I will let you know the quote and whether I go ahead with this in the fullness of time. I will try and do a cost-benefit analysis and get a pay-back period, if I am able!

FD

[scrumpyjack]

The newly published October 2022 price cap rates (in my area, Yorkshire) are 10.3p per kWh for electricity and 33.8p per kWh for gas (ignoring standing charges).

FD

I thought the new price cap for Electricity is about 36p per kwh so am surprised to put it mildly that you say 10.3p!!!!!
My current rate is over 30p before the increase from Oct 1

[AF62]

That is a ratio of 3.28, and a heat pump should be at least 4 times more efficient than a gas boiler. So as far as I can see, it will be cheaper to produce a kW of heat using a heat pump than a gas boiler for the foreseeable future (at least the next 2 years).

Trouble is that ASHP efficiency isn’t 4:1 and the SCOP is frequently lower, particularly if you have them generating hot water over 35c (and that’s before you get to the electricity consumed in the defrost cycles when it is freezing outside).

And if you are heating your home with low temperature hot water then the heating needs to be on 24/7 so you need to take account of the additional heat loss during the unoccupied hours, as well as the cost of all the additional insulation.

ASHP are a good idea for a few new highly insulated homes which are occupied all the time. But as retrofit to existing badly insulated homes, doubtful.

[Itsallaguess]

The thing is, this solution is hedging my bets. I will have electric and gas heating solutions available to me, and hot water from the gas boiler. I think this could provide a medium term (maybe 10 years) solution until the gas boiler gives up, or gas boilers are banned, or the price of gas is no longer economic compared to electricity.

If anyone is interested, I will let you know the quote and whether I go ahead with this in the fullness of time. I will try and do a cost-benefit analysis and get a pay-back period, if I am able!

I think your proposal sounds like a good hedge-betting solution fd, and as someone who has considered a similar set-up, I'd certainly be interested in some more details of your quote such as approximate cost and also some make and model details of the internal and external elements if you'd be good enough to please post them up?

Another board member, Howard, has had a similar installation linked below -

https://www.lemonfool.co.uk/viewtopic.php?f=9&t=34905&p=509659#p509659

He went for the Mitsubishi units, so I'd be interested to compare your own elements with the ones he's been running for a while now and seems very happy with them from the above post.

Out of interest - did they quote for kit and/or installation, or was it a job lot?

Just interested as to what level of granularity they went down to with costing the individual elements, that's all...

Cheers,

Itsallaguess

[Howard]

Still very happy with my aircon. Doesn't use much electricity.

It's much quieter, externally and internally, than our modern gas boiler.

When the boiler is working hard in cold weather its exhaust is noisy. The ASHP fan has a quieter hum.

There are a couple of large new houses near me with massive ASHPs close to footpaths which (out of interest) I've listened to carefully. They too are pretty quiet.

regards

Howard

[Mike4]

The Daikin Sustainable Home Centres appear to be independent installers rather than part of Daikin themselves. Link here giving a list:

https://www.daikin.co.uk/en_gb/energy-f ... ntre.html#!#Book

[BullDog]

Still very happy with my aircon. Doesn't use much electricity.

It's much quieter, externally and internally, than our modern gas boiler.

When the boiler is working hard in cold weather its exhaust is noisy. The ASHP fan has a quieter hum.

There are a couple of large new houses near me with massive ASHPs close to footpaths which (out of interest) I've listened to carefully. They too are pretty quiet.

regards

Howard

Interesting, thanks. I suggest (if you didn't do so last winter) is to walk past those same houses when the weather is close to or below freezing and the heat pumps are running flat out. Be interesting to know in the real world how noisy they are then compared to now. Quite a bit louder I should think when running flat out.

[Mike4]

And there is the Planning Permission issue I have heard mentioned several times now. The outdoor heat pump heat collectors need planning permission apparently, according to the odd newspaper article I've read. But I've yet to discover the true position with any authority. Does anyone here know?

[BullDog]

And there is the Planning Permission issue I have heard mentioned several times now. The outdoor heat pump heat collectors need planning permission apparently, according to the odd newspaper article I've read. But I've yet to discover the true position with any authority. Does anyone here know?

Here's what government policy says on the matter -

https://www.westminster.gov.uk/planning ... heat-pumps