Heat Pumps, One for the engineers

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Paul-R
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Re: Heat Pumps, One for the engineers

Post by Paul-R »

If one decides to go for the type that buries pipes in the ground, what sort of minimum depth do they have to be put laid?

The reason is that our gaff in France doesn't lend itself to placing the heat exchange radiators on the outside wall. This is the north side of the house and as you can see it's virtually on the road.
BILD0925a.jpg
It's not good practice to put them on the south facing walls as they get really hot in summer which leaves ground burial. And here we come to the next problem. The water table is only about a metre underground and this makes digging deeper difficult - our next-door neighbour had many ground pumps running when they installed a sunken swimming pool. What sort of area needs to be available per room or square metre?

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NewcastleFalcon
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Re: Heat Pumps, One for the engineers

Post by NewcastleFalcon »

Paul-R wrote:
30 Apr 2021, 18:38
If one decides to go for the type that buries pipes in the ground, what sort of minimum depth do they have to be put laid?
No personal knowledge Paul but this lot say this
https://www.homebuilding.co.uk/advice/g ... heat-pumps

"There are two main elements of a ground source heat pump system: The ground array, which can be either a horizontal grid of pipes, which should be 1.2m below ground level, or two or three vertical boreholes, which are likely to be more than 70m deep."
Regards Neil

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Paul-R
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Re: Heat Pumps, One for the engineers

Post by Paul-R »

"There are two main elements of a ground source heat pump system: The ground array, which can be either a horizontal grid of pipes, which should be 1.2m below ground level..."
Well that could be a problem
"... or two or three vertical boreholes, which are likely to be more than 70m deep."
:shock:

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NewcastleFalcon
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Re: Heat Pumps, One for the engineers

Post by NewcastleFalcon »

NewcastleFalcon wrote:
30 Apr 2021, 09:47
Gas Boilers are soon to become persona non grata, and go the way of the internal combustion engine. The only alternative purported is either direct electric heating or heat pumps ground and air source, together with better insulation.

I could go away and do a bit more research and I probably will, but give me an armchair ride with your own thoughts to get us started.
How do they work :?:
Why are they currently so expensive :?:
DIY could you make one in your shed what components would you need :?:

Words are good, pictures, pen and pencil drawings better :-D
I will regard the thread as a success with a single response, a page or two would be brilliant.
Brilliant so far, but now that page 2 has been reached I will exit my armchair temporarily and bring into the fold a renowned authority about air sourced heat pumps, local north-east lad George Clarke possibly earning a crust or two from Mitsubishi. Where do Mitsubishi Electric have their Factory....good news...Livingston Scotland.



Regards Neil

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Re: Heat Pumps, One for the engineers

Post by Gibbo2286 »

Interesting George but you left out the price. :-D Let's take a look at another of George's comments in another video.

First, remember you still need to fund the full capital cost of the kit and installation and not everyone has a spare £7,000-£10,000 (or more) lying around!

Secondly, (and this is what drives me mad about government red tape!) not everyone that installs an air-source heat pump will qualify for the RHI.
Last edited by Gibbo2286 on 01 May 2021, 10:10, edited 1 time in total.

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Re: Heat Pumps, One for the engineers

Post by NewcastleFalcon »

Gibbo2286 wrote:
01 May 2021, 09:58
Interesting George but you left out the price. :-D
He did say with the grants etc it pays for itself over 7 years :-D ... but I would agree that prices for the gubbins and installations are high. Are those units any more complex than a gas boiler :?: They should be able to churn them out at a comparable price, and if there needs to be a transition period of scaling up, target the assistance at making the things rather than the installations. Again the installation for the air source variety is the type of thing plumbers have been doing for years, hot water tank and an output from a "boiler".

Here's the factory tour at Livingston. I like George I he's a good presenter, pleasant, enthusiastic, informative.



Regards Neil
Last edited by NewcastleFalcon on 01 May 2021, 10:17, edited 1 time in total.

Gibbo2286
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Re: Heat Pumps, One for the engineers

Post by Gibbo2286 »

When I had my new gas boiler fitted some thirteen years ago it was a Combi as recommended by the greenies at the time which meant that the tank in the loft was removed, the added cost of a new tank to go with the Ecodan system seems to be around another £2 to 3K.

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Re: Heat Pumps, One for the engineers

Post by Dormouse »

A new 14kw Ecodan heat pump plus cylinder - £9600. Fitting is from £1000 in the Midlands/South Yorkshire area

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Re: Heat Pumps, One for the engineers

Post by Peter.N. »

Up to 300% efficiency - what's its efficiency at near freezing temperatures?

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Re: Heat Pumps, One for the engineers

Post by Dormouse »

There is a good article on air heat pumps on Wikipedia. No efficiency figures are quoted but in every article I have ever read it says they work at their most efficient in mild climates. They will work at low temperatures but efficiency tails off. How much? No one was ever prepared to say - always a bad sign I think.

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Re: Heat Pumps, One for the engineers

Post by Dormouse »

The quoted 300% efficiency ( COP ) is almost certainly against electric resistant heaters - ie electric power consumption of the air pump against direct electric heaters. What it doesn't include is the immersion heaters in the storage cylinder.

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Re: Heat Pumps, One for the engineers

Post by Peter.N. »

Yep, we used one to heat our bedroom for many years and yes, we did get a good heat output at normal winter temperatures but once it dropped below freezing the efficiency ratio was about 1 to 1, in other words a 1kw convector heater would have given the same output. You are then talking about 18p per kwh, electricity being by far the most expensive form of heating. As previously mentioned our oil fired boiler provides it at about 5p per kw. We couldn't afford to heat our home with one, its expensive enough now.

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Re: Heat Pumps, One for the engineers

Post by Dormouse »

Interestingly, no one so far has mentioned extracting heat from running stream water.

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Re: Heat Pumps, One for the engineers

Post by myglaren »

I wonder if it would be cost-effective if I were to breach the wall to next door and suck the heat out of their house?
Do you think they would notice?

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Re: Heat Pumps, One for the engineers

Post by mickthemaverick »

If you're going to breach the wall Steve it might be simpler just to tap into their radiator circuit with your rads :-D