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Building thermal insulation.

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Zero999:

--- Quote from: tom66 on July 25, 2022, 07:06:58 am ---You can also get monobloc heat pumps:
https://les.mitsubishielectric.co.uk/products/residential-heating/outdoor/ecodan-puhz-monobloc-air-source-heat-pump

which can be installed by a regular plumber, as all the air con stuff is in one self-contained unit.  These, in theory, just fit in place of the heating loop in your property, though you may require some radiators to be changed to handle the lower delta-T.

These cost ~roughly 2-3x the cost of a gas boiler right now.

Personally I'd keep the gas boiler as a backup and use air source heat pumps for the majority of the time.  For the odd day that goes below 0C where heat pumps roll off in efficiency, I can switch to gas.  It's a shame I'll have to pay a gas connection fee all year round but I guess someone's got to pay for the infrastructure.

--- End quote ---
It's not the cost of the heat pump itself for many people. Heat pumps don't provide instant hot water. I have a combi boiler, which heats the water as it's being used. A heat pump would require a hot water cylinder to be fitted, costing more in pipework, labour and space. At the moment, it wouldn't pay for me to fit a heat pump. I'm better off paying the mortgage off more quickly, or investing the money in stocks and shares.

tom66:
Maybe I'm thinking about this in the longer term but a hot water tank is a benefit, not a cost.

Combi boilers are inefficient for heating hot water because they produce it on demand: they need to burn a tremendous amount of gas to get the heat exchanger up to temperature, if the system hasn't been used for heating recently.  I recall the calculation being that if your system takes 30 seconds before upstairs taps have hot water, then it burned about 200Wh of gas just getting to that point, let alone any actual usage.  It's fine if all you do is take showers (runtime >> startup time), but if you wash your hands with warm water, then it's not going to take many cycles before that pays off.

Whereas a tank, whilst it does use space, consumes relatively little 'lost' energy (our tank is ca. 1kWh/day and better ones do exist) that's made up by the lack of cycling.  And once we have a home with solar, excess power from that can divert into the tank, or cheap electricity can be bought overnight to charge it up. 

You can also get electric instant hot water, usually around 9-12kW.  More expensive than a combi though, and a bit slower admittedly, but an option if you don't want a tank and still wanted heat pumps.

I'm a big fan of 'inflationary hacks' and energy efficiency is one of those.  Paying the mortgage down quicker is also sensible;  it depends on your longer term opinions on energy prices...will they go down or stay where they are, or even go further up?

Zero999:

--- Quote from: tom66 on July 25, 2022, 07:38:34 am ---Maybe I'm thinking about this in the longer term but a hot water tank is a benefit, not a cost.

Combi boilers are inefficient for heating hot water because they produce it on demand: they need to burn a tremendous amount of gas to get the heat exchanger up to temperature, if the system hasn't been used for heating recently.  I recall the calculation being that if your system takes 30 seconds before upstairs taps have hot water, then it burned about 200Wh of gas just getting to that point, let alone any actual usage.  It's fine if all you do is take showers (runtime >> startup time), but if you wash your hands with warm water, then it's not going to take many cycles before that pays off.

Whereas a tank, whilst it does use space, consumes relatively little 'lost' energy (our tank is ca. 1kWh/day and better ones do exist) that's made up by the lack of cycling.  And once we have a home with solar, excess power from that can divert into the tank, or cheap electricity can be bought overnight to charge it up. 

You can also get electric instant hot water, usually around 9-12kW.  More expensive than a combi though, and a bit slower admittedly, but an option if you don't want a tank and still wanted heat pumps.

I'm a big fan of 'inflationary hacks' and energy efficiency is one of those.  Paying the mortgage down quicker is also sensible;  it depends on your longer term opinions on energy prices...will they go down or stay where they are, or even go further up?

--- End quote ---
It depends on your usage.

I hardly ever use hot water, so that would be 1kWh/day up in smoke. I live on my own. I normally shower cold and use cold water to wash my hands, as hot dries my skin. If I need hot water to wash the dishes, I boil a kettle, but I find modern detergents are so good I can use cold if they're not very greasy.  The hot water from the combi boiler is used occasionally, normally when I have guests over who want a hot shower. I have the thermostat set to a cool 15°C and it's only on for 6 hours a day on work days and a bit more when I'm off work, although I'm often out.

I doubt the energy savings of a heat pump would ever pay for its upfront cost, then there's all the inconvenience and hassle of getting it done which is more of a deterrent than the money for me.

tom66:
Yeah, that's fair enough - you're probably a rounding error in terms of savings.

Still, it disappoints me that new properties are being built with combi boilers still.  It's a really bad decision.  These should be super-insulated and use small heat pumps to provide heating and cooling.

themadhippy:

--- Quote ---as most places have huge subsidies for installation, prices skyrocketed, especially with companies licensed to install the "right models" on the list for those subsidies.
--- End quote ---
And strangely the price increase is around  the same amount  as the subsidy.

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