Ground Source or Air Source Heat Pump
Discussion
Having lived in the Midlands for many years, and now running a heat pump business in NZ I can assist.
For space heating of one room an air sourced unit is the best value - just get a named brand one (personally I prefer Mitsubish Heavy Industry). Even at very low temperatures they will still operate, although at reduced efficiency.
A new build is a totally different thing - air source is best value for NZ- some properties in the UK may be best with ground source - but it isn't cheap to install.
More details if you want more information.
For space heating of one room an air sourced unit is the best value - just get a named brand one (personally I prefer Mitsubish Heavy Industry). Even at very low temperatures they will still operate, although at reduced efficiency.
A new build is a totally different thing - air source is best value for NZ- some properties in the UK may be best with ground source - but it isn't cheap to install.
More details if you want more information.
Just bought a house with GSHP. First electric bill, even before it got this cold, was £280 for the month... and even then the house wasn't really warm. To be fair, it is a reasonably sized stone-built farmhouse with sandstone mullioned window frames and steel single-glazed windows - so not exactly thermally efficient.
Have now got the GSHP on its "winter mode", and it is keeping the house warm, but not looking forward to this month's bill.
Have now got the GSHP on its "winter mode", and it is keeping the house warm, but not looking forward to this month's bill.
We have two air source heat pumps. They are rated to give the equivalent of 1.5 kilowatt heating, so struggle to heat our 16 square metre living and bed rooms anyway. It was minus four last night, inside and out, and it took around 15 minutes for the room to feel in any way warm. I put one on to take the chill off the room while I lit the log-burner, they would not be near powerful enough to maintain 18 degrees on their own. During very cold weather, below minus six or so, they cycle through a 'defrost' phase every ten minutes or so, during which they deliver no heat at all, but sound like an old 'Teasmade' hissing away.
They are fine for 'push button' heat on a chilly autumn evening, but for winter heating, forget it.
They're ace air coolers when it's forty degrees outside though.
They are fine for 'push button' heat on a chilly autumn evening, but for winter heating, forget it.
They're ace air coolers when it's forty degrees outside though.
tokyo_mb said:
Just bought a house with GSHP. First electric bill, even before it got this cold, was £280 for the month... and even then the house wasn't really warm. To be fair, it is a reasonably sized stone-built farmhouse with sandstone mullioned window frames and steel single-glazed windows - so not exactly thermally efficient.
Have now got the GSHP on its "winter mode", and it is keeping the house warm, but not looking forward to this month's bill.
OP is in the UK and you are in Japan ?Have now got the GSHP on its "winter mode", and it is keeping the house warm, but not looking forward to this month's bill.
Steve Carter (on here) had A GSHP put in http://www.stevecarter.com/otherstuff.htm
Hi,
I have a ground source heat pump, have has it running for ~12 months now. The condensor does seem to be running more in this cold snap, but it's to be expected, because the difference in temperature between outside, and inside is greater. In the summer my bills were around 18units a day, now it is nearer 25, but still not bad compared to oil.
I live in a stone built chapel conversion in the hills, so it's not got the easiest life - although my place is very well insulated.
Running UFH throughout.
Tom
I have a ground source heat pump, have has it running for ~12 months now. The condensor does seem to be running more in this cold snap, but it's to be expected, because the difference in temperature between outside, and inside is greater. In the summer my bills were around 18units a day, now it is nearer 25, but still not bad compared to oil.
I live in a stone built chapel conversion in the hills, so it's not got the easiest life - although my place is very well insulated.
Running UFH throughout.
Tom
thing with gshp & ashp are to get the best out of them you need to have a complete system.
I'm a building services design engineer (electrical) though, and i was up at a site today we've just handed over. The patients move in next week.
This particular site has 200kW of gshp, and 200kw of gas boilers.
The gshp is running through 12 boreholes.
It's sole purpose is to feed the underfloor heating.
Today the underfloor heating was calling for 40d C. It was taking all 200kW of heat pump to provide that and a few times the BMS was dropping it in favour of the gas as it was taking too long to achieve it's temp. The Glycol was 9dC.
It's quite impressive to see 40dC coming out of it though.
If you haven't got underfloor htg though, it's far harder to get a higher temp out of it for radiators or fcu/ahu's
Mate of mine is building is own house and has underfloor htg and plenty of room to run the gshp pipework up and down his orchard.
Meant to add:
In a month we will be handing over another unit in Rochdale that we've put ashp's in, so will be interesting to see how that performs. It was -13 up there the other morning so anything's going to struggle with that. That site also has a pellet Biomass boiler and gas boilers.
I'm a building services design engineer (electrical) though, and i was up at a site today we've just handed over. The patients move in next week.
This particular site has 200kW of gshp, and 200kw of gas boilers.
The gshp is running through 12 boreholes.
It's sole purpose is to feed the underfloor heating.
Today the underfloor heating was calling for 40d C. It was taking all 200kW of heat pump to provide that and a few times the BMS was dropping it in favour of the gas as it was taking too long to achieve it's temp. The Glycol was 9dC.
It's quite impressive to see 40dC coming out of it though.
If you haven't got underfloor htg though, it's far harder to get a higher temp out of it for radiators or fcu/ahu's
Mate of mine is building is own house and has underfloor htg and plenty of room to run the gshp pipework up and down his orchard.
Meant to add:
In a month we will be handing over another unit in Rochdale that we've put ashp's in, so will be interesting to see how that performs. It was -13 up there the other morning so anything's going to struggle with that. That site also has a pellet Biomass boiler and gas boilers.
Edited by davethebunny on Wednesday 8th December 21:15
I work for a building mechant,and one of our customers has built a modern eco home.he is running two air source pumps,which heat his fair size home,the house has huge amount of insulation throughout.asked him about the air source system,they were not cheap, pumps were 4k alone,heat output is reasonable but he was dissapointed with the running costs.now he's {with government grant}put solar panels on the roof to generate electric ,which he sells back to national grid,but he says it's a pityfull amount compared to the electric those pumps use.
For colder climates I would suggest GSHP with boreholes is better due to more consistent ground temps and therefore higher input temp into system. If the air is -10C then any ASHP will struggle. GSHP with ground at say 10C at 50M depth is quids in but expensive to install!
I remember a farmer friend many years ago had a huge steaming mountain of manure on site, he laid 200m of flexible pvc pipe through it with a tap on the end, when he wanted hot water he simply turned on the tap and it supplied pretty warm water.
I remember a farmer friend many years ago had a huge steaming mountain of manure on site, he laid 200m of flexible pvc pipe through it with a tap on the end, when he wanted hot water he simply turned on the tap and it supplied pretty warm water.
peterperkins said:
For colder climates I would suggest GSHP with boreholes is better due to more consistent ground temps and therefore higher input temp into system. If the air is -10C then any ASHP will struggle. GSHP with ground at say 10C at 50M depth is quids in but expensive to install!
I remember a farmer friend many years ago had a huge steaming mountain of manure on site, he laid 200m of flexible pvc pipe through it with a tap on the end, when he wanted hot water he simply turned on the tap and it supplied pretty warm water.
i know someone who did a similar diy scheme for the swimming pool. Piped the filter pipework through a hose that was sandwiched between a piece of black plywood and an old patio door. Nicely warmed the water, and you could turn it to face the sun.I remember a farmer friend many years ago had a huge steaming mountain of manure on site, he laid 200m of flexible pvc pipe through it with a tap on the end, when he wanted hot water he simply turned on the tap and it supplied pretty warm water.
Have a big old place with radiators to heat here in France. Have recently replaced a huge 30 yr old fuel oil boiler with a Mitsubushi Zubadan air source heat pump with a small oil boiler as back up for the cold weather. Previously the boiler had to stay on all year to supply hot water - now that is handled by the heat pump.
Below around 5 degrees the heat pump is straining to get the rads properly hot - once the oil burner cuts in at 0 degrees things get better! I think ultimately we'll save alot of money on running costs, but the system wasn't cheap - heat pump alone was around 12 k€.
Ground source heat pump would have been better for the higher temperatures required for rads, but you need flat land without big trees that you can turn into a permafrost tundra. I'm on a hill, with bloody great oaks all around me....As I recall, your underground network needs to cover around 1.5 times the surface area that you want to heat.
Below around 5 degrees the heat pump is straining to get the rads properly hot - once the oil burner cuts in at 0 degrees things get better! I think ultimately we'll save alot of money on running costs, but the system wasn't cheap - heat pump alone was around 12 k€.
Ground source heat pump would have been better for the higher temperatures required for rads, but you need flat land without big trees that you can turn into a permafrost tundra. I'm on a hill, with bloody great oaks all around me....As I recall, your underground network needs to cover around 1.5 times the surface area that you want to heat.
GuinnessMK said:
Has anyone got a house with either an air source or ground source heatpump?
Just wondering how they were fairing during this period of inclement weather?
I was working on an air source unit last week, it was -0.5 deg C air temp, the unit was consuming just over 2Kw of electricity and producing 7 Kw of heat, the radiators were easily up to 45 DegC in the hour or so I was there. (from about 17 deg)Just wondering how they were fairing during this period of inclement weather?
A heat pump will need to run longer than a boiler (gas or oil) to achieve full operating temperature, and won't reach as high a temperature but will/could be more cost effictive depending on the price of gas/oil. And as described above is way more efficient than staright electric heating.
One problem I am finding with underfloor systems is that they units aren't being run for long enough to build up sufficient heat in the slab.
Heat pumps are both very simple and extremely complicated at the same time, and great care should be taken concerning specifications before installation.
To heat an existing house that doesn't have UFH it's important to realize the limitations. A high wall heat pump will only heat one area - with standard height ceilings 1Kw of output per 10sqm is a rough sizing guide - when it's really cold outside it probably won't get the area hot enough. Going for a named brand inverter drive will help - Mitsubishi Heavy Industry, Mitsubishi Electric, Panasonic, Fujitsu, Toshiba, Daikin, Hitachi are all good.
Existing underfloor heating may be a problem with an air sourced hot water heat pump in the UK. AFAIK the pipes in the slab are usually in a thin screed which means there is minimal heat storage ie it's a fairly quick response system. Hence you have to heat when it's cold outside which is not favourable for an air sourced unit.
A standard New Zealand house has a four inch concrete floor slab. When water pipes are buried in this there is enough stored energy to last overnight, hence an air sourced unit can be run in the day....and the coldest mid day temperatures for much of New Zealand is at least 7 or 8 degrees, just above the temperature where an air sourced unit needs to defrost.
With efficiencies of say 5:1, and relatively cheap renewable electricity - and air sourced unit with UFH is ideal for NZ - but it doesn't necessarily work for the UK.
Ground source operates at any time of the day with the same efficiency, and of course is fine for a thin screed floor slab with little storage.
Personally I would try and fit water pipes into a well insulated four inch floor slab with a new build in the UK - and decide on the heating method dependant on location, finances available, etc etc.
Just remember with the floor pipes, maximum of 200mm spacing. This means you only need warm water (ours run at a maximum of 35 degrees) which makes a heat pump even more efficient.
Note: there are two types of heat pump. Traditional high wall units that blow warm air around, and ones that heat water where the water then transfers energy by being pumped round. Both types can be air sourced or ground source. High wall air sourced are cheapest (from about one thousand installed), ground sourced hot water systems the most expensive. Follow the Carter link above.
To heat an existing house that doesn't have UFH it's important to realize the limitations. A high wall heat pump will only heat one area - with standard height ceilings 1Kw of output per 10sqm is a rough sizing guide - when it's really cold outside it probably won't get the area hot enough. Going for a named brand inverter drive will help - Mitsubishi Heavy Industry, Mitsubishi Electric, Panasonic, Fujitsu, Toshiba, Daikin, Hitachi are all good.
Existing underfloor heating may be a problem with an air sourced hot water heat pump in the UK. AFAIK the pipes in the slab are usually in a thin screed which means there is minimal heat storage ie it's a fairly quick response system. Hence you have to heat when it's cold outside which is not favourable for an air sourced unit.
A standard New Zealand house has a four inch concrete floor slab. When water pipes are buried in this there is enough stored energy to last overnight, hence an air sourced unit can be run in the day....and the coldest mid day temperatures for much of New Zealand is at least 7 or 8 degrees, just above the temperature where an air sourced unit needs to defrost.
With efficiencies of say 5:1, and relatively cheap renewable electricity - and air sourced unit with UFH is ideal for NZ - but it doesn't necessarily work for the UK.
Ground source operates at any time of the day with the same efficiency, and of course is fine for a thin screed floor slab with little storage.
Personally I would try and fit water pipes into a well insulated four inch floor slab with a new build in the UK - and decide on the heating method dependant on location, finances available, etc etc.
Just remember with the floor pipes, maximum of 200mm spacing. This means you only need warm water (ours run at a maximum of 35 degrees) which makes a heat pump even more efficient.
Note: there are two types of heat pump. Traditional high wall units that blow warm air around, and ones that heat water where the water then transfers energy by being pumped round. Both types can be air sourced or ground source. High wall air sourced are cheapest (from about one thousand installed), ground sourced hot water systems the most expensive. Follow the Carter link above.
caziques said:
Existing underfloor heating may be a problem with an air sourced hot water heat pump in the UK. AFAIK the pipes in the slab are usually in a thin screed which means there is minimal heat storage ie it's a fairly quick response system. Hence you have to heat when it's cold outside which is not favourable for an air sourced unit.
That is why we are going for a thermal store along with our air source heat pump.Gassing Station | Homes, Gardens and DIY | Top of Page | What's New | My Stuff