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Air source heat pumps

stavros said:
I've done no research myself, but that sounds very low at first glance. I'm sure my new combi cost at least twice that a few years ago, without any new radiators.
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Yeah, I did do a bit of rudimentary research into replacing the gas boiler, and I think that would have cost at least £1200 plus probably the same amount in labour. I guess without the government grant this would all cost £10,000.
 
Leafster said:
I think you can get electric combi boilers which could replace a gas one.
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I had an electric boiler in to provide hot water when the wood burner wasn't lit. When I looked into them anything above about a 12 kWh boiler required a 3 phase electrical supply which you don't get in most houses. :hmm:
 
teuchter said:
This just isn't true. Maybe it was partly true with early heat pump systems but it isn't now.
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Not sure I believe that. Most heat pumps only heat the water to around 40°C and there are still a hell of a lot of older homes around that don't have cavities to insulate and little or no loft insulation. :hmm:
 
WouldBe said:
Not sure I believe that. Most heat pumps only heat the water to around 40°C and there are still a hell of a lot of older homes around that don't have cavities to insulate and little or no loft insulation. :hmm:
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It's just not true that most heat pumps only heat to 40 degrees. Yes, in an ideal world you do run them at low temperatures because it's more efficient but the system is designed to suit the property.

Yes there are a hell of a lot of homes with poor insulation. Which is why there needs to be loads of investment in improving the housing stock.
 
lazythursday said:
It's just not true that most heat pumps only heat to 40 degrees. Yes, in an ideal world you do run them at low temperatures because it's more efficient but the system is designed to suit the property.
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Got a link for that as when I looked into them they would only heat to 40°C.

If central heating normally runs at 60°C you would have to replace all the radiators with ones 50% bigger to get the same heat output. If it normally runs at 80°C you would have to double the size of the radiators. Who has the room to do that? :hmm:
 
The one Octopus is installing in my house will be 50 degrees. This is apparently their usual approach as it minimises the need to oversize radiators. My radiators will be a bit bigger but really not by much at all. Some are the same size but with an additional convection unit.

Either you are completely wrong or I will shortly have a freezing cold house. We shall see.
 
I was looking at an air-to-air multi-drop heat pump with one connection upstairs and one downstairs. The portable heat pump I've got heats my one room upstairs nicely of an evening.
 
lazythursday said:
The one Octopus is installing in my house will be 50 degrees. This is apparently their usual approach as it minimises the need to oversize radiators. My radiators will be a bit bigger but really not by much at all. Some are the same size but with an additional convection unit.

Either you are completely wrong or I will shortly have a freezing cold house. We shall see.
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If you've insulated you'll be fine. My rads run at about 43°C and the house is well toasty but I was referring to the uninsulated houses.
 
The interesting bit will be the effect on your fuel bills.

It was regularly on the news sometime back where people had been persuaded to have a heat pump installed and their fuel bills had tripled as a result, wether that was because they hadn't had the insulation upgraded or not I can't remember.
 
WouldBe said:
Got a link for that as when I looked into them they would only heat to 40°C.
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You could try the internet.

There's a trade off of efficiency vs water temperature. But even the ones that produce water at the same sort of heat as a conventional boiler do it at greater efficiency than a straightforward electric heater.

As you say, if you can increase your radiator sizes, you can make it work with lower temperatures. In some houses it's tricky to increase radiator sizes, and in some it's trivial.

Each house will be different. But lack of insulation doesn't mean heat pumps are ruled out. It just means that the heating will cost more. Just like with any kind of heating.

And at the moment, gas heating will still work out cheaper for many people. But the question is what to do after gas is no longer an option and at present, heat pumps look like the most obvious solution and hydrogen really doesn't.
 
Is there a comparison in effectiveness between water heating and air heating heat pumps? Porsche's statement that all engines are air cooled it's just that some car manufacturers insist in putting water in the way comes to mind (only in reverse).

Won't some of the hot water driving radiators be wasted? One thing about direct air heating is that it's very quick to warm up.
 
two sheds said:
Is there a comparison in effectiveness between water heating and air heating heat pumps? Porsche's statement that all engines are air cooled it's just that some car manufacturers insist in putting water in the way comes to mind (only in reverse).

Won't some of the hot water driving radiators be wasted? One thing about direct air heating is that it's very quick to warm up.
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I guess he never owned a jetski.
 
two sheds said:
Is there a comparison in effectiveness between water heating and air heating heat pumps? Porsche's statement that all engines are air cooled it's just that some car manufacturers insist in putting water in the way comes to mind (only in reverse).

Won't some of the hot water driving radiators be wasted? One thing about direct air heating is that it's very quick to warm up.
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Iirc Water can carry more heat than air so moves it to where it's needed more easily.
 
WouldBe said:
Iirc Water can carry more heat than air so moves it to where it's needed more easily.
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Might be, although the portable heat pump warms up the room really quickly. I'd imagine a water based system would take longer to warm up and longer to cool down.

Some of the heat would be dissipated in the heat pump itself and the pipework (although that would be insulated).
 
two sheds said:
Might be, although the portable heat pump warms up the room really quickly. I'd imagine a water based system would take longer to warm up and longer to cool down.
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You'd need a heat pump in each room though.

(In some countries this is kind of what they have, in the form of AC units)
 
lazythursday said:
I have a radiator in my living room about 120cm x 500. If you increased it to, say, 130 x 750 it would hardly make a difference in terms of space required.
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And if they are single panel you can sometimes change them to double, or from double to triple, without needing to change the W x H at all.
 
teuchter said:
You'd need a heat pump in each room though.

(In some countries this is kind of what they have, in the form of AC units)
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Yes particularly for larger houses. My place is an old miners' cottage so quite small and I think a unit in the central room upstairs and central room downstairs might do it. It seems to be working that way with the dehumidifiers.

There's also only me, and I'm downstairs during the day (although in the conservatory which doesn't need much heating) and upstairs at night. As you say, though, heat pump in each room would be more of a general rule. I was only looking at two units with a multi-drop air heating system, I think four or five units would be quite common.

I did some work for a company that was saying that water-heating heat pumps are better with underfloor heating than radiators, although that's pretty well all going to be new builds.
 
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