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Comment by monkeynotes | Hacker News Reader

Is that £10k for a mini split system? I'm not sure how many homes would need to spend that much. The UK is full of small flats and 2 up/down places that could rely on maybe one or two splits, Google shows that a decent setup would be about £2k plus installation (two splits each at £1k inc tax).

Given the hot summers and energy costs in the UK I think many homes would find that investment a net gain.

> There's also the consideration of additional costs due to lower running temperature which often necessitate larger radiators.

I don't know what that means. There are no radiators for mini splits or air source heat pumps, maybe you are talking about ground source hot-water systems? They are still stupidly expensive, for good reason, huge install consideration.

Today's low upfront cost of mini split heat pumps makes for a highly favourable option for new builds, and indeed even the average home.

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> Is that £10k for a mini split system?

It was 2021 when I last last looked into it but I recall that 10k was the list price of the cheapest air source heat pump that wouldn't result in a net increase in energy bills. I don't believe it included installation or any other associated costs.

> Given the hot summers and energy costs in the UK I think many homes would find that investment a net gain.

It's almost unheard of for UK homes to have any sort of cooling installed.

> I don't know what that means. There are no radiators for mini splits or air source heat pumps, maybe you are talking about ground source hot-water systems? They are still stupidly expensive, for good reason, huge install consideration.

UK homes are mainly heated with hot water radiators in each room; typically by an on demand gas combi-boiler that also handles hot water. Heat pump installations in the UK typically heat a hot water tank[0] that provides domestic hot water and heats the radiators.

Due to poor insulation the gas central heating systems typically run at around 60-80c. Heat pumps here usually heat the water to around 40c. This will often require replacing existing radiators that were installed expecting ~70c flow temperature with oner that can disperse more heat into the room. It can also involve additional insulation.

> Today's low upfront cost of mini split heat pumps makes for a highly favourable option for new builds, and indeed even the average home.

Indeed, heat pumps are a sensible choice for most new build homes in the UK as well. They typically have much better insulation and are therefore less affected by the low flow temperature. The costs involved in retrofitting anything older than 10, maybe 20 years old were.

[0] https://solarthermuk.co.uk/wp-content/uploads/2020/12/air_so...

If you are looking at air to water heat pumps you will certainly be looking at much more expensive installs. Mini splits are way cheaper and don't require hooking up to the gas hot water system which can simply be retired to backup heat source.

And yeah, cooling is not a thing in the UK, my point is folks are definitely going to be looking toward that given the summers people have been having, increase heating costs will make mini splits a double win. No brainer to me and I bet mini splits will be in limited supply this summer in Europe.

I'm not sure how they'd work to be honest. The doubts I have about them:

* How would the heat be moved around the house?

* Obtaining permission to modify the exterior of a multi-occupancy dwelling is extremely difficult.

* You'd still require a source of hot water, reducing the already small savings over an efficient combi-boiler.

Based on the estimated savings of the Energy Saving Trust, it'd take around 26 years to pay off a £3k install that replaces a modern combi-boiler[0] and that's without the cost of using electricity to provide heated water. As recently as March of this year Which claimed most houses would have paid an extra £80/year if running a heat pump[1].

They could be a good choice for completely new installs and people stuck on resistive electric heating if they can find a way to disperse the heat evenly. I'd bet a lot of money that the majority of properties with electric heating are rentals, good luck convincing a landlord to pay for anything.

[0] https://energysavingtrust.org.uk/advice/air-source-heat-pump...

[1] https://www.which.co.uk/reviews/ground-and-air-source-heat-p...

Goes to show the huge differences in different countries for energy costs. Our electricity is $0.11kw/h and natural gas is $0.08 so with 300% efficiency vs. gas air furnace which is probably 50% efficient (so much heat gets lost in leaky ducting). Our heat pumps will have paid for themselves in ~5 years conservatively, and we also get to cool the house which we could not do before.

Moving the heat around the house requires doors to be open and thoughtful placement of the head units which have fans in them to push the air around. It is certainly not ideal but we are comfortable.

There was an article the other week:

https://news.ycombinator.com/item?id=34233719

Obviously it depends on ability to scale, but UK rad heating systems are usually rated for 50 or 60C, thus this seems to fit the bill.

Cool! I hope I didn't come across as hating the technology. In a perfect world I hope we'd be using geothermal district heating but while we're still installing units in individual homes I think heat pumps are currently the best way forward. The economics of retrofitting many standard homes simply don't really line up in many cases. Prior to the current energy crisis they were generally more costly than using gas and even after they only really make economic sense for the relatively small number of people stuck on electric heating[0].

Home renewables help but require even more capital investment, often taking 10 or more years to pay off. It doesn't help that where I am solar has extremely limited output in the winter. Domestic wind turbines are difficult to situate and get planning approval for. My cursory impression is that they're also less economical than many solar installs.

I've got some roof repairs coming up soon and I'm hoping the economics of replacing the existing roof with some nice looking solar slate tiles work out favourably!

[0] https://www.statista.com/statistics/426988/united-kingdom-uk...

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