You may be covering it with your second definition, but I'm not sure - there's also the option available in Ireland (and UK and elsewhere) of a wet heat pump. By that, I mean an air-source (or ground heat extracting) heat pump that connects to the existing wet radiator infrastructure of the house. Replaces a gas boiler, which is normal here.
Interesting. I live in Dublin, we have a terrace house so it's not that large. When we bought it 12 years ago we did a complete renovation (decent insulation, new gas boiler). Since everything works, I don't want to rip everything out and junk it. But I was think about filling the south-facing roof with PV solar and installing two air-source heat pumps. I was hoping to cool the house in summer and heat it from March to October for free. Plus in the sunniest months, divert extra electricity from PV to the hot water tank. But I intended to leave the gas boiler in place as a backup. Maybe I shouldn't. Anyways, if it ever breaks down I'll just have it removed.
One option is to use a ground-source heat pump in that kind of situation, if you have enough land to dig or drill to install the exchanger pipes. Most places in Australia where I live are able to just use air source but I've seen ground source ones in Europe.
This is called a Storage heater (https://en.wikipedia.org/wiki/Storage_heater), usually referred to in the UK as a Night Storage Heater as it took advantage of cheap electricity at night to provide heat for a house.
Fitting Night Storage radiators was a much cheaper way of fitting central heating than the normal boiler and plumbing approach, and when electricity was cheaper it made more sense. Now, it makes no sense and if you buy a house with it the first thing you have to do is put in "proper" central heating. But maybe with excess renewables that will swing back.
How are heat pumps typically installed? Are they integrated into the radiator/hot water system? Or is some sort of forced air system setup installed?
I'd assume a mini split setup wouldn't be too uncommon. (Probably the cheapest route for most homes in the UK).
In the US the vast majority of homes and apartments are setup with forced air heating and cooling which really simplifies transition. I'd assume the UKs setup where everyone uses heated water to heat homes would make transition more expensive and costly.
I was attempting to be srcastic and explain that mounting a radiator on a wall connected to a gas boiler would be an improvement on what we have here. Also, many places in the UK and Ireland have insulation on exterior walls already.
What is it that would make it so expensive? (edit: ah you meant the renovation not the heating system) A good heat pump for a large house is sub €10k. Of course you need some way of distributing the heat in the building too (water radiators or in floor heating). Is it that the houses completely lack radiators? Retrofitting a heat pump to a home that has a water radiator system and with fossil burning boiler is cheap.
I’m replacing my 20 year old heat pump now with a new one and it’s around €8k installed. At the same time I’ll tear out the floors and radiators (replacing the floor anyway) and replace with heated floors. This costs at least another €20k but isn’t really necessary - that’s just a luxury when changing the floors anyway.
Good thing around here really old houses have 200mm insulation and newer ones have 300+ required by the code. Regulation also bans fossil heating or direct electric for any new construction or major rebuild.
In northern Europe where ground source heat pumps are increasingly popular, houses built with those typically heat via coils installed in the floors. As you say, with only lukewarm water radiators by the windows (the traditional solution for oil/wood/etc. heating) aren't enough.
The town I live in is bisected by a MOD railway and, from what I understand, permission was never granted for whatever was needed to supply natural gas on my side of the tracks. This rules out some of the more common traditional heating systems found in these parts.
We bought the house ~two years ago. The building itself was (and still is) quite sound but was a wreck in terms of features (no heating system at all, no flooring at all, and in terms of a kitchen and bathroom facilities it was quite ... minimal).
My partner had long hoped for underfloor heating downstairs as she loves the feel of walking on warm flooring. I have to agree that it is a delightful luxury and we don't otherwise have too many vices.
Direct electric underfloor heating felt like the least hassle in the long term and the easiest for self-installation. The alternative was a wet underfloor heating system (water filled pipework set in screed). The wet system is capable of leaking and eventually failing with expensive repairs, the electric system less so.
We use infrared wall-mounted heaters upstairs. As far as direct electric heaters go they're quite efficient. They heat the objects in the room rather than the air and it feels like the warmth of the sun on your skin.
I agree wholeheartedly that heat pumps are a more efficient option and could indeed be used as a direct replacement for our upstairs wall-mounted heaters. This is something we hope to put in but was not previously affordable when we were re-working the entire of the inside of the house from nothing.
As far as I understand, we would need a wet system for underfloor heating if we were to utilise heat pumps and at this stage that would be a prohibitively expensive re-work of what we already have.
Hopefully roof-mounted solar and a battery of some sort should even out the costs a bit.
For where I live in London, ground heat pumps are infeasible and air heat pumps would produce too much noise and not be permitted under conservation area rules.
What most of the UK needs is an effective drop-in replacement to a combi boiler, ideally one that doesn't need a large water storage cylinder. It could even be a combination of a slow boiler (for radiators) and a fast water heating unit (for bath/shower/taps).
Any retrofit of air or ground heat pumps into Victorian terraces just wouldn't work or be acceptable.
As yet no comparable electric version exists at similar price, size, capability. This is where a govt can incentivise innovation to both create what we need, and then help it be deployed (first with a stick like banning things, and second with a carrot like helping those in poverty get it for cheap/free).
For new homes absolutely. In the UK gas boilers are the norm and every new home should have a heat pump instead.
But retrofitting requires a lot of work - replacing radiators with much larger ones, maybe ripping out pipes, and for ground source digging up the garden / street.
a closed-loop refrigerant system that uses water lines to the indoor coil/air handler
Sounds like an air to water monoblock heat pump. Common in Europe. But you can only get the water up to about 50C efficiently. Not as good as refrigerant. So you need a large radiator to get the heat out into the room. Using wet underfloor heating as a giant emmitter works well. But otherwise it makes them tricky.
Some people are trying for minisplits with propane in the lines which is not a greenhouse gas so they hope anyone will be able to install it without a licence.
Are you referring to an hvac boiler for heat? That can be replaced with efficient air source heat pump. Have a link to one of these example combi boilers?
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