Heat pumps? Not so convinced now.

[Vortex2]

We thought that fitting an air source heat pump to our new eco house 3 years ago was a wizzo idea.

Clean, tidy, provides both warm air and hot water, needs just a fridge sized box in a room corner.

Looking back it WAS a good idea - mainly because it kept the local Planners happy .. and I like 'high tech'!

It was expensive 'tho ... £13k+.

Today I am having second thoughts :
* We need new filters regularly - at £200 a year.
* it runs (cheaply) on mains electricty ... a single point of failure for the whole house.
* We have an air-tight house so we did not design in any form of alternative heating.
* The machine was built in Denmark so spares could take days/weeks to arrive
* Professional engineers will be needed to do any repairs.

Overall it now seems like an unexploded bomb about to go off at some random time in the future.

Until thess gadgets are in use everywhere, with local parts stores and plenty of skilled service staff, they are a bit of a risky choice ...

[adam2]

I agree. Heat pumps show some promise but are not in my view a mature technology.
Whilst availability of spare parts and experienced service companies will no doubt improve, they are INHERENTLY expensive and complex machines, with most faults not user repairable.
Totally reliant on electricity.

And it is only a matter of time until TPTB require that persons repairing or servicing heat pumps hold some special and expensive certification, a bit like CORGI/Gasafe but more expensive.

And as for £200 a year for replacement filters, you can buy a significant amount of electricity for simple resistance heating for £200.

For EXISTING buildings of poor thermal efficiency my favoured options would be either a wood burning stove, or gas central heating. This later is not a long term option, but a gas boiler installed this year should be serviceable for at least 10 years. A lot can happen in 10 years.

For NEW CONSTRUCTION I would favour extreme insulation and mechanical ventilation with heat recovery. This will need very little heating, and this modest demand can be met affordably from simple direct acting electric resistance heating. Although still reliant on electricity, such a home will remain comfortable for some hours, and tolerable for some days without electricity.

Cost of heat pump=£8,000, or say £800 a year if it lasts 10 years which might be optimistic.
Filter replacements=£200 a year.
Annual service and repairs, my estimate, £300 average over 10 years.

About £1,300 a year, and of course the electricity to run it. This might amount to another £500 a year.

£1,800 a year will buy a a lot of electricity for resistance heating. Argos have electric heaters for £10 !

[BritDownUnder]

I can only bring my Australian experience but here is my tuppence worth.

I have three air source split systems (so an inside and outside unit) basically heating, and very importantly for Australia cooling, a room each.

A fairly mature technology in Australia with a lot of local knowledge in fixing.
Maximum power draw per unit is 1 to 2 kW at full load. I think cooling uses slightly more power than heating as with heating you get COP + 1 efficiency so about 4x rather than COP efficiency for cooling, assume COP (coefficient of performance) is about 3. SO you get three times the heating or cooling out as the compressor puts in as work.
Totally reliant on electricity as you say. I probably could run them on an inverter and they are branded as "inverter" heat pumps but meaning something slightly different.
If I had my own way and the money I would build a massive earth sheltered house to take advantage of the ambient soil temperature here of about 20 degC and not needing heating or cooling.
Heat pumps generate a small amount of distilled water each day ( I would guess about 1 litre per hour of operation) which is of some use for gardening.
Filters on mine can be cleaned by a vacuum cleaner and reused as mentioned before.
I try to run my heat pumps when solar is being generated by my rooftop system.

If I just had to heat a place and I had concrete floors I would seriously consider underfloor heating either by resistive heating or by water pipes. I have had one break in five years that was a 'failed card' and was replaced under warranty.
If just heating I would probably go for storage heaters and not heat pumps unless I had the money to go for ground source heating and underfloor pipes.

A lot of refrigerants are also significant greenhouse gases.

I hear that a company in the UK called Kenza sell a heat pump unit (ground source) for about 3000 pounds.

[kenneal - lagger]

I always recommend to clients that they have an alternative method of heating, in the countryside usually a woodburning stove. There are quite a few room sealed ones available so they won't compromise the air tightness of the house nor cause draughts in the room they serve. With optimum siting they can heat most of a house and all of a very well insulated house with maybe some help from a bimetallic heat powered fan.

It is a lesson that I learned in the early 1980s when we had a week of heavy snow and my elder daughter was born and had just come home from hospital to an eight day power cut. The central heating went off so we were reliant on our wood burning stove plus a small amount of heat from our radiators which were arranged on a pump assisted gravity feed from the wood burning cooker. Our neighbour, a carpenter, was very upset because I had advised him to put in a wood burning stove rather than the open fire which he had installed in his newly built house and they were just about warm in the draughty living room and cold elsewhere. We were warm as toast! We had hot air going out the top of the door from the living room where the log burner was to the rest of the house at 36C and coming back in at floor level at 16C. As long as we kept out of the way of the return draught we were comfortable.

I was outside cutting logs and saw the overhead supply wires cross in the wind under a heavy weight of snow and short two phases. I phoned the electricity supplier and told them what had happened and about my new born daughter but they were very unsympathetic as there were only eight houses affected and were busy elsewhere. Eight days later they got round to us and took about five minutes to locate and change a fuse just as the weather warmed up again!

I learned then never to rely 100% on the mains supply.

[adam2]

The recent energy price increases and expected further increases might shift the balance away from heat pumps.

Electricity is about 30 pence and gas about 10 pence a unit.
Presuming a heat pump COP of three, that shows no direct saving by use of an expensive and complicated heat pump.

3 kwh of gas burnt in power station will produce about 1 kwh of electricity.
1 kwh of electricity in a heat pump will produce about 3 kwh of heat.

Alternatively, burn the gas directly and get about 3 kwh of heat, saving the capital cost of the power station and of the heat pump.

If renewably generated electricity becomes cheaper, or gas becomes even more expensive then heat pumps may become more attractive, but at present the economics are doubtful.

[clv101]

The whole point of heat pumps is to facilitate non-fossil fuel heating, wind, nuclear, solar etc. Sure, today a lot of electricity is generated from gas, and using this to power a heat pump instead of simply using the gas directly is rather pointless - that isn't the aim of heat pumps.

[PS_RalphW]

I just had an energy efficiency survey done on a new(ish) house I am buying. It reported that fitting a heat pump would cost £15,000 and cost more to run than the existing new(ish) gas boiler. There is no way I will get those economics past my better half, especially as she feels the cold more as she is getting older, and needs the flexibility to crank up the heat when the arthritis is bad.

That said, solar panels are an obvious win as is more insulation.

[BritDownUnder]

I have thought a lot about a heat pump hot water heater but the costs are off putting compared with a simple immersion heater. Even if the efficiency is better the cost and ongoing maintenance might not prove economic.

Also I think the COP is quoted at +7C and heating may be required at lower air temperatures than that.

[kenneal - lagger]

The human race has been making economic decisions about the best way to heat our homes, i.e. the cheapest way to heat our homes for well over a hundred years now since fossil fuels became available for home heating and look where economic decisions have got us: into a climate crisis! Why? Because economics takes no notice of environmental costs. On this forum we all know this but are, like everyone else, still constrained by the money in our pockets to what we can afford.

The government knows this but is unwilling to take the right action to counter this economic idiocy because they are constrained by the banking system which is addicted to growth. The only way they will solve this problem in the longer term is to change the banking system to a zero interest system so that growth is no longer an imperative. In the meanwhile the government could institute a National Scheme to insulate our houses to save the 80% that their own Climate Change Committee has mandated and they have agreed. Will they do this? I doubt it because it would hit the growth that they are so addicted to.

Insulating our houses would bring the cost of installing a heat pump down drastically because the heat pump required would be much smaller and the existing central heating system would be large enough to distribute the much smaller amount of heat required at the lower circulation temperature around the house. There would also be savings to be made on upgrading the already creaking electricity distribution system not to mention the saving on building a nuclear power station or two with the lower generation required to power the smaller heat pumps.

Now if we were to mandate smaller EVs as well just think of the savings to be made there as well!

[adam2]

The whole point of heat pumps is to facilitate non-fossil fuel heating, wind, nuclear, solar etc. Sure, today a lot of electricity is generated from gas, and using this to power a heat pump instead of simply using the gas directly is rather pointless - that isn't the aim of heat pumps.

I agree, but it will be hard to persuade Mr average to pay say £10,000 for a heat pump if it costs more to run than a gas boiler.
Heat pumps will only become attractive when they offer a significant saving in total heating costs over gas or oil.

Whilst the electricity price remains "pegged" to about three or four times the gas price, then heat pumps are most unlikely to make sense.

[kenneal - lagger]

That is why the government have banned the sale of gas boilers from a date, which I can't remember, far enough into the future to make it the responsibility of another government to enforce with the hope that something will happen before implementation to make it more palatable to the voters. If a Tory government is in charge at the time and there are no mitigating circumstances they can always find an excuse to delay the implementation.

Am I getting cynical in my old age?

[Mark]

How can the UK turn from Europe's heat pump laggard to leader ?
https://www.linkedin.com/pulse/how-can- ... n-rosenow/

[Mark]

but on the positive.....

Waitrose adds in-store Heat Pumps to tackle energy price rises:
https://www.grocerygazette.co.uk/2022/1 ... eat-pumps/

[Ralphw2]

Government delays introduction of heat pump quotas by a year, which would have forced gas boiler companies to install an increasing fraction of the heat pumps in place of gas boilers, from April 2024. Now the timetable will start in April 2025

Yet another back down by the government on its environmental commitments.

[northernmonkey]

Anything that is highly dependent on complex technologies and long supply chains, especially if it is something important like home energy systems or personal transportation, is a bad idea in my opinion.

The simpler the better. I now apply this principle to all aspects of my life. Even when it may appear, in the short run, to be "less efficient" than the more technologically advanced alternatives.