Heat Pumps

[User]

 

[slowmotion]

If you want to save money, you will be better off using a modern gas boiler, assuming you have a mains gas supply. DECC commissioned a 700 dwelling field study to ascertain the efficiency of heat pumps installed in "the real world" rather than a laboratory.. The reports came out recently. Google DECC, Heat Pumps and Energy Saving Trust.
I worked on the contract but I'm probably bound by a secrecy clause so I won't say any more.

 

[KnackeredBike]

The hospital building I work in had ground source heat pumps installed in 2012, environmentally friendly heating and cooling promised.

Five years later the heating is provided by new gas boilers and the cooling doesn't work at all.

Not to say that one installation proves anything, but if ground source was easy to get right people would be using it on an industrial scale too.

 

[Levo-Lon]

The average water temp of cold water in the UK is around 12°C ,so that's from burried water mains.
Recently the cold water entering my work place has exceeded 20°C which is over our allowed legionella safe max temp. Water board can supply upto 25°C on cold water.
So I'd think its never a great way to heat a building..but id love to see it work well.

 

[green1]

I've just started digging the trenching for the heat pump on our new build. I'm digging 2x300 metre loops using a 9" bucket rather than doing wider trenches and putting the pipes down either side. Space isn't an issue for me so I can spread the pipes out over a wider area.

 

[green1]

That would be ready for backfill.

I doing 2 separate loops 300 long going into a manifold. I'm trying to get them as deep as possible. That means 6-7ft with the machine I've got, the sub soil is basically hardcore so difficult to go deeper with the size of bucket I'm using.

 

[Drago]

@green1 interesting stuff! We need pics and details!

 

[Globalti]

That looks like a small scheme for a smallish house. My pal has just done one for a large barn conversion; he dug five trenches 100 metres long and put two pipes like that out and back in each, total 1000m of pipe. A neighbour did one a few years ago with 850m of pipe laid in coils in two much wider trenches but with closely coiled pipe there's actually a danger of freezing the ground, this is after all a giant fridge you are installing with the house as the radiator at the back. The danger of freezing explains the need for separation.

We heat our house with a gas boiler and an Aga but I installed a 20 tube array on the roof, which gives us all our hot water in summer and cost me £700 as a DIY project.

 

[threebikesmcginty]

The average water temp of cold water in the UK is around 12°C ,so that's from burried water mains.
Recently the cold water entering my work place has exceeded 20°C which is over our allowed legionella safe max temp. Water board can supply upto 25°C on cold water.
So I'd think its never a great way to heat a building..but id love to see it work well.

Heat pumps extract residual heat that you wouldn't be aware of. We have an air to water heat pump that heats our underfloor system even when it's freezing. I think it works by magic or something. Expensive to buy, cheap to run and we get a rebate, I think it'll stack up in the end.

 

[Yellow Saddle]

The average water temp of cold water in the UK is around 12°C ,so that's from burried water mains.
Recently the cold water entering my work place has exceeded 20°C which is over our allowed legionella safe max temp. Water board can supply upto 25°C on cold water.
So I'd think its never a great way to heat a building..but id love to see it work well.

It doesn't quite work like that. Just like the room's ambient temperature has no bearing on the temperature inside your fridge or freezer, so the ambient temperature of ground water or indeed the ground, has little to do with the temperature delivered inside the house. Don't assume you get what's underground.

 

[Yellow Fang]

It can be quite difficult to say how much heat those ground loops collect. It depends how deep the trenches are, thermal conductivity of the soil, the height of the water table, the collector design, how long the trenches are, average surface temperature. Small domestic heat pumps have about a 6 kW thermal output but about 2 kW of that would be electricity.

 

[Levo-Lon]

They are a big spend...



A rough guide would be £1,000 for each kW of power required to heat your home. Costs vary depending on the size of your home, how well insulated it is and how long ago it was built. For a 3 bedroom house built since 1960 it would probably cost around £5,000 for an air source heat pump and £7,000 for a ground source heat pump plus around £2,500 for the installation. Then you need a special hot water tank and perhaps additional radiators, possibly another £3,000. If you chose a ground source heat pump it will cost extra to bury the pipes outside, say another £5,000 to £15,000. Although this is expensive compared to a traditional boiler a well designed heat pump installation can save up to 50% on your heating bills and the government will be paying you via the Renewable Heat Incentive for 7 years for domestic installs and 20 years for non domestic installations. The payment for the Domestic Renewable Heat Incentive is designed to compensate you for the additional cost of installing this carbon saving technology. The Non Domestic Renewable Heat Incentive is designed to provide a 10% return on your investment.

 

[green1]

@green1 interesting stuff! We need pics and details!

Between 6 and 7ft deep. 140m done only another 460 to do.

 

[biggs682]

My pumps are warm and smelly if it helps

 

[Milzy]

Buy a Kingspan heat pump, they’re really great.