Air source heat pump

BUDFORCE said:
I'd personally have no interest in getting a heat pump, if anything I'll probably look to replace our oil fired boiler before they are phased out to get another 20+ years out of it.

We have solar so we are already doing our bit for the environment.
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This is a bit of an odd take. Space heating, particularly oil, is by far the most significant element of your properties carbon emissions.

A decent oil boiler is putting out 320g of CO2 per delivered kWh of heat.

Last year the U.K. grid average was 151g a heat pump should be running at a SCOP of 350% so that’s more like 43g per delivered kWh of heat.

Typical property is using 10,000kwh of heat a year so over 3 tonnes of CO2 per year. The heat pump will be 430kg and will reduce over time with the grid. It will also be materially cheaper than oil to run given it’s more expensive than gas.

Now I don’t think many would ordinarily advocate to ditch a perfectly good working boiler but to opt for a further oil boiler (particularly when the government is paying for most of the alternative) because you are already doing your bit is a bit with a solar array is definitely up there with interesting takes.
 
bimbleuk said:
toasty :)

There have always been high temp HPs but with Octopus you could ask to be put on the list for a Cosy 6. Uses propane I believe and can run as high as a boiler. Though Octopus design their systems to run at 50C so they don't change so many rads. Makes their overall BOM costs lower.

You'll see many recommendations of 45C flow temp used to get near the 400% efficiency SCOP. If I get near 350% I'll be happy.

I improved my loft insulation to around 370mm recently and it was immediately noticeable. Heat loss calcs during the site survey indicated that the smallest 4KW HP was more than adequate to heat my mid-terrace house.
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You shouldn't be running your boiler at 80C either!
 
bimbleuk said:
I don't, mines set to around 50-55 tops I think. BUT if you were crazy enough to do so there are HP options out there is what I meant.
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There are, but I don't think they're particularly popular for domestic use. If you have a big thermal store, you can have a great dT across your entire system, even if your flow temperature is only 55C. You can basically store a boat-load of energy generated at 80C. In fact, natural refrigerants or hydrocarbons are typically happier running at a slightly higher flow temperature, and their capacity and COP is often dictacted by the system dT.
 
I’d echo b0rn2sk8’s words. If you can afford to, we all need to do our part to reduce CO2 emissions. A heat pump is a great way to achieve that and with the generous grant and Octopus’s mass rollout, not always expensive.
 
Ormy1 said:
This. Gas boilers can put out hot water at 80C no problem. Heat pumps usually only manage 40-50C, which means for the equivalent amount of heating you need to have it working for twice as long as your boiler would have been, and have twice the surface area of radiators in the house. That's just one of the many reasons for modification. Gets very expensive very quickly.

When I looked into it, I realised spending the money on more solar capacity (if you have space) and more battery capacity was a better use of the money.
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Not really, you need to get better rads or even fan assisted ones and it’ll heat up the room quicker and won’t have to work ‘twice’ as hard. No one needs 80ºc water that’s ridiculous for a house.
 
SoliD said:
Depending on tariff still cheaper for gas due to the way electricity price is calculated in the UK...
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It shouldn’t be.

You’ll be lucky if your gas boiler is running an average of 90% efficiency, even for a modern condenser.

The only way to get up into the 90’s is low flow temperatures, bigger radiators, weather compensation and a water cylinder with a big coil just like you’d use in a heat pump and requires a lot of retrofit work (like a heat pump) to get those numbers.

The electricity price is just over 4x the gas price currently but a gas boiler isn’t 100% efficient. At a very generous 90% efficiency, you only need a SCOP of 3.7 to beat it based on Octopus price cap prices.
 
Reuben klang said:
Not really, you need to get better rads or even fan assisted ones and it’ll heat up the room quicker and won’t have to work ‘twice’ as hard. No one needs 80ºc water that’s ridiculous for a house.
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First, you misquoted me, I said twice as long, not twice as hard. Second, this is basic thermodynamics, not an opinion. Also I never said anyone 'needed' 80C flow temp, it was an example for the sake of the comparison I made.
 
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