GSHP: The green tech even carbon sceptics will like Today on the environmental front: some news that ought to please most people, for a change. The government is being urged - by its own researchers - to get behind a home energy technology which could seriously cut into both carbon emissions and (if you don't care about those) energy bills and future gas imports from Russia. We …
£12000-£15000 to have the garden dug up, buy the heat pump and install underfloor pipes - the lower water temperatures produced by GSHP are best suited to underfloor heating.
So those government grants would need to be pretty substantial to beat the typical £3000-4000 cost of installing gas central heating. Start talking about a Combined Heat and Power gas boiler and you have a more achievable solution.
GSHP is currently best suited to new installations or replacing oil-fired boilers which are not in reach of the gas grid.
If we are to use electricity as a means of heating properties, then heat pumps may be essential to improve efficiency. However, quite apart from the cost of installation of the pipework and heat pump to extract heat from the ground, it doesn't end there. Heat pumps are not immune from the laws of thermodynamics, and the stated efficiency levels (3-4 x the energy put into operating the pump) is only achieved at the cost of generating heat at relatively modest temperatures. That's reasonable if you want to generate warm, room-temperature air or, possibly, gentle warming of floors over a very large area, but it is wholly incompatible with the type of system installed in a typical UK household. Those type of hot-water radiator system rely on high temperature water (typically 6-70 degrees centigrade), Try an use a heat pump to produce water at that temperature, and the efficiency would plummet.
What that tells you is a couple of things - firstly, don't expect to couple a ground source heat pump into the pipework previously used by a boiler system. You will require a wholly different type of heating infrastructure. Also don't expect such a system to produce the hot water at a temperature that can be used for baths or showers - or at least not without losing a lot of efficiency or just as a pre-heater (which amounts to the same thing - loss of thermal efficiency).
This is all without the potentially high costs of maintenance of a bulky and mechanically complex heat pump.
I rather suspect that it is much more cost-effective for the average UK household to spend their money on improving insulation. After all, that (generally) has low maintenance costs and is much less disruptive than digging up large areas and replacing all your heating pipework.
Heat pumps have a bigger role in making use of industrial waste heat and, possibly, for new builds than a retro-fit. The apparent something-for-nothing nature of heat pumps might look attractive, but for most folk, there is a more cost effective route, and it's called insulation.
It is. We've had ours over here in Sweden for many years now, but the £10000 to bore the well and install the pump and heat-exchanger hurt. If i hadn't plumbed in the radiators myself it would have hurt a lot more. On the other hand, the value of the house went up and it's -12C outside, but the house is toasty!
A few problems with the report.
1. This type of installation requires drilling to a depth which in the UK is strictly regulated and requires a permit from the UK geological survey. So you have to fight for 6 months+ for a permit (and based on the trouble it takes to get a water well permit you are not likely to get it). After that you have to buy a unit abroad, find an installer (which in the UK again may require special permit, etc), etc.
2. The really cheap types of installation where you drill two boreholes put a stick of dynamite down on the bottom to crack the rock a bit and run water down, water up are unsuitable for the UK. Most of UK is unfortunately limestone or even worse - chalk. Compared to the UK Scandinavia sits on top of a nice granite shelf. There, the water pumped down is not going anywhere but coming up the neighbouring "up" borehole. In the UK the same water will dig a nice cavern where your house will subside or run off instead fo coming up via the other borehole.
However, the UK is still suitable for other types of heat pumps which are used in places around the world which sit on limestone like the mountain part of South of France, US Mid-west, etc):
1. Air-exchange heat pumps. An air exchange heat pump unfortunately is pretty useless under 5C. In the 5-15C (which is most of the year in the UK) it can provide the same efficiency boost as a ground bore (up to 3 times) to electric driven central heating and water. Not perfect, but way better than using "naked leccy". Probably marginally more cost effective than gas even at current prices.
2. Spring water exchange heat pumps. Same principle as the ground bore, but you use water from a nearby stream or river. If regulated properly (after all, we do not want to freeze all of our rivers, do we?) it is a viable option for 50%+ of the UK. So the flooding menace which you hate running through your piece of suburbia can suddenly become a source of heat to all inhabitants.
Groundsource also works with vertical boreholes so the area of land required is actually quite small, if loads of these type of systems were installed then the price of boring would probably fall to less than that of digging lots of trenches on the surface.
There are also airsource heat pumps which work almost exactly like air-conditioning units in reverse, removing heat from the air outside and putting it inside (as hot water). These work even with air temps below 0C but are obviously less efficient than GSHP but much cheaper and easier to install.
These are the kind of decent energy saving thing people should have been persuaded to install years ago - not pathetic wind/solar where 1kW is about as good as they get for residential installations. With GSHP you could put in 6kW of electric and get 18kW of heat out constantly. A 12kW wind turbine would be huge in comparison both physically and cost-wise.
I am considering a geo-sourced heat pump when my 9 year old standard unit finally dies. The downside is I need to decide if I want to put out the $5-7K extra cost over a standard air-sourced heat pump.
Here in Florida the electricity savings can be pretty substantial. But like everything it's a matter of working out the cost/benefit ration and pay back time on the initial investment. At least here in the states most homes have a large enough lot to have room for the required wells to install the piping loop in.
Now that's a 'green' technology I could genuinely live with - I have both back and front gardens that I can dig up if I feel like it.
It would make far more genuine difference to my 'carbon footprint' than switching to an electric car, even if such a thing really existed.
However, I'm not going to replace my gas-guzzling backboiler until I know which technology is actually the right (and most importantly, most reliable) one, and the Government stops playing stupid buggers with the subsidies and taxes.
I really like the idea of having a heater that is up to about 500% efficient. (You put in 1kW of electrical energy, and get out about 5kW of heat!) Interestingly, today's technology appear to include air source heat pumps so you don't need the (expensive) ground exchange loop.
There are grants available under the LCBP programme of, apparently, 900 UKP minimum for an air source heat pump and 1200 minimum for a ground loop (for homeowners). OTOH a random search on t'interweb indicates that a new ground source heat pump costs about 10k UKP, so it's still bloody expensive. An air source heat pump appears to be about 6k.
* GSHP work because the temperature of the ground about 1.5-2m down is pretty constant all year round.
* GSHPs do need a three phase supply to drive the motor as they typically need to pump a huge volume of anti-freeze through the pipes in the ground.
* The CoP for GSHPs is usually quoted as 4 but more typically its probably about 2.5-3 when you take into account the level of quality of the installation.
* If you don't have the land you can dig down, typically a 100m straight down. A bit more expensive to drill down but cheaper than buying the land!
* An alternative to GSHPs is ASHP where the A stands for Air. Basically an air-conditioner that can work in both directions. Not as efficient as GSHPs but useful in the situations where GSHPs can be installed.
* Nice idea about attaching fridges and other heat dumping equipment (air-conditioners) to the system since you could dump excess heat into the ground in summer ready to pull it out in the winter.
Most of the installations are what we call "bedrock heat", or something along those lines. Instead of running pipes horizontally near the surface, you make a single deep hole down to where it's hotter. Takes less space that way.
Illustrations and easy to read Swedish info over at http://www.energimyndigheten.se/sv/Lattlast/Hur-ska-du-varma-upp-ditt-hus/Varmepump/
This isn't new to me, but it's good to see the light of reason dawning in a government-influencing institution like this. Let's see how long it takes our politicians to completely mess it up.
It's a very good fit for the UK as most of our older housing stock is Victorian (terraced) houses with gardens. Said gardens can be easily dug up to fit the necessary bits of piping.
It's not much use in high-rise city centres, but there's an awful lot of parkland dotted around London which could be used to provide shared heating and cooling systems for these areas too.
I can't remember a series of Grand Designs where the majority of the new builds *didn't* use ground source heat pumps. Has somebody somewhere finally noticed?
If I understand the technology right, you can if necessary also use the ground in the summer as a source of cold, ie cut the energy cost of air conditioning.
How's about an honourable mention for air-sourced heat pumps too? We've all seen them, in the "twin pack" air conditioners used in offices and server rooms etc. Now reverse the plumbing to bring heat *in* from outside. Some of them even take heat from the outside air and put it into water for the traditional central heating. OK the air temperature tends to be a bit more variable than the ground, but in most parts of the UK most of the time it's perfectly practical.
Air sourced heat pump technology may not be quite as exciting as the ground source stuff but it is at least applicable to buildings which are already built. There are a lot of those about. No one's going to rebuild specifically so they can get a ground source heat pump, some people *might* invest a few thousand pounds (on the domestic scale, for an existing building) for an air source setup.
You rather breathlessy charge off from mentioning that GSHP is a good means for regulating home temperatures (which is true) into running freezers and ovens (which is not true). The problem is the Second Law of Thermodynamics; while there is a fairly small temperature difference between dwelling space and the heat source/sink underground, there is a much bigger difference between an oven or freezer and that same heat pipe. That means the efficiency of the system will drop off dramatically for these applications since the quality of the thermal energy is low compared to the magnitude of the temperature difference at the 'business end'.
Flames because, well, you know.
Using the earth as a heat sink/source is all very well, but what about some serious heat: geothermal? Its not just for the Icelanders. Just a few kilometers beneath our feet, the fires of hell rage, just waiting for the LHC to... Oh wait, wrong rant.
As pointed out, the up-front costs are prohibitive, but governments and globocorps alike can easily finance such a project.
Cost.
An acquaintance is building his own home from scratch, and was looking at various heating solutions, including GSHP.
Looked like it would cost over £10k to install, which he baulked at - and that was if he hired a digger and dug the trenches himself.
So then HM Govt, offer to cover 50% of the cost of *that*, rather than using stupid stamp duty 'holidays', and you might actually get somewhere.
Steven R
...I had friends that were using this concept, but with their swimming pools as the heat source/sink. Made for a warm pool in the summer, though...
Just get a commercial-grade liquid heat exchanger heat pump (or just A/C if you're that inclined) and connect it in with the pool pump. Much more efficent than air exchange, and doesn't require digging up the yard. Of course, it only works where you have liquid water all year. Or a river you can (il)legally dump heat into.
A farmer who I know built himself a new house on his own land and installed a ground source heat pump system - but it cost a lot and needed quite a bit of land. So maybe we could do with some parameters so that I can work out if my 70ft x 20ft back garden is big enough and if my bank manager can afford it. Over Xmas I'm putting in that £1 a roll extra loft insulation that the govt is subsidising...
The ground is not an unlimited source of heat; one problem that GSHPs have had in the past is the ground around the extraction pipes freezing. Once that happens, efficiency drops dramatically. This is more of a problem in northern latitudes.
Once the freeze occurs, it takes a long time for the ground to thaw, forcing the use of conventional methods of heating, thereby reducing the savings and overall efficiency.
Incidentally, the current level of CO2 in the atmosphere is in the area of 0.0035%. The easiest ways to reduce it is to plant trees and tell environmental activists to shut up.
netgeek
yup - GSHP are a great idea. Until you start trying to find a suitable "govt approved contractor" whose price eats up any subsidy you might be given :(
Also, it's most suited to underfloor heating, as the water is best raised to about 30C rather than 70 for radiators. My own plans fell by the wayside when the cost (not including groundworks) when way over £7K.....and as for having the house converted to be suitable for underfloor - just the 30K!!
Great for a newbuild tho - and I'd recommend underfloor (water) heating, which is all that survived from the GSHP project in the new kitchen.
I was thinking of how my neighbours would react if I dug up my garden and buried stuff in it. Then I had a brilliant idea. I just need to put in an anonymous tip in that there are illegal immigrants in my rose bushes and some bunch of nosey parkers will come round and dig up the lot for me.
I get 2 bonuses then. Labour saved and a warm feeling that some part of our xenophobic system has been fooled into leaving the vulnerable alone for a while...
Unless you already have a deep underground network say the "Tube" or a deep mine for example, the green credentials wander slightly when cost of energy is cast against the cost to drive a Bore hole,deep enough...the cost of the geological survey with some guarantee that the return water just doesn't disappear sideways and a vain hope to get a reasonable return on the investment in ones own lifetime. It would help to ensure that you actually have a closer to the surface geologically active environment to start with, cue, pictures of arctic snows across fields of basalt. Its Economics My Boy Economics!!!!
Every house owner I know here in Sweden has fitted a heat pump - cheap, plentiful hot water & heating, ultra reliable and a very quick ROI. It doesn't require much digging or space either.
Factories & offices in and around Stockholm use the same technology for cheap air conditioning. Also, power stations here use the waste heat from combustion to pump steam around the city through insulated pipes to provide heating to buildings. Incredibly efficient compared to dumping the heat though cooling towers. Plus they can store up to 48 hours worth of superheated steam in large tanks to cover ups and downs in heat production, sudden cold snaps etc.
It's old and proven technology and now would be a good time for Britain to invest in this kind of infrastructure and create some jobs at the same time.
According to without hot air http://www.withouthotair.com/ electric powered heat pumps are even more efficient than gas powered hot water systems. http://www.inference.phy.cam.ac.uk/withouthotair/c21/page_150.shtml
Its a no-brainer really - any new house should have a heat pump system by law.
The one up in Fort Bragg keeps the house between 68F and 72F 24/7, and maintains the water heater at about 120F (We kick on the burner when we are in residence). The one here in Sonoma is is similar, but we need to augment it with an air conditioner when the outside temps climb much higher than the mid-90s. We are off the grid in Fort Bragg, so I don't know how much energy we are saving (I don't monitor it because, frankly, I don't care) ... But total energy costs in Sonoma are a LOT lower than they were before installation, in the neighborhood of 65% lower. The up-to-date and modern insulation I installed at the same time probably helps considerably. Recommended.
Oh, and if you don't have the horizontal space, you can go vertical ...
Sounds lovely and its hard to get a plumber round here whose not busy putting them in. However you here few stories about them being wonderful in practice and too many bad stories of people who find it takes alot more electricity to get the heat than they were expecting, not to mention installation and maintenance. its hard enough keeping our central heating going smoothly.
Back in the late 80's British Gas research labs were looking at using heat pumps for domestic heating, though those were driven by natural gas-powered internal combustion engines (in a very well sound-insulated box!) Never understood why they didn't make it it to customers really - they were a hell of a lot more efficient than using the combustion heat directly. On second thoughts I do get it - British Gas pushing tech to reduce gas consumption?
We looked at this, and it has some very severe disadvantages, enough to make it basically impractical. The first is the cost, we are talking 10-20k for an installation. The second is disruption - they will dig a trench 100 meters+ long in your garden. and lay the pipe in it. This means up one side and down the other. The third is much more serious. If you don't get the dimensions right, what happens is that you produce permafrost in your garden, at which point the whole thing has gone pear shaped. You can no longer cool the ground any more, which is how you get the heat out in the first place.
All in all, this is a hare brained scheme, on any scale. Two much more practical technologies are first, to insulate the house properly. This is cheap, effective. it makes an absolutely huge difference to both cost and comfort for very little outlay and little disruption. If you are comparing it to 10-20k for the ground source heat pump, just spend a quarter of that and you will get an absolutely superb insulation job even in the most difficult circumstances. Roof insulation is one thing, then there's cavity wall and cladding.
The second thing, which is less efficient in theory than the ground source heat pump, is an air source heat pump. Much, much cheaper, and you are not going to produce permafrost. Yes it may be less efficient, but its more cost effective.
There is a reason why ground source heat pumps have not taken off. They are not very sensible.
I can say this is true because I have such a unit. We built a 2000 sqr ft home three years ago in Iowa, USA. Buried a 1500 ft glycol line around the house about five feet deep, connects to unit in basement. In winter, unit brings in latent heat from ground into house, in summer it runs the other way and dumps house heat into ground. Only thing the commercial electricity does is run the pump. Mean Jan temperature is about 20F, summer in July about 85F. I figure portion of electric bill for heating/cooling is never more than $20 per month. Neighbor with roughly similar house has conventional natural gas HVAC unit and pays about $140 per month in Jan and July. It cost about 3x more to install than conventional unit but will pay for itself in next year or so. Yes, it really works.
I realise you need a flippant ending, but you need to be more than just digging up the garden to install these. Mine are about 4m under the surface. Putting one in an existing site is also difficult, running a large diameter pipe into an existing building can be tricky.
Also, note that since I'm in Adelaide and the air temperature is very hot here, that I'm actually using these as "cool pipes", delivering air that is well under the ambient temperature to the input of the evaporative air conditioning and the to back of the fridge, freezer and computer rack. The installation had to be designed when the house was rebuilt, so that it could come up through the foundation slab.
Note that there wasn't any one technology that had a massive payoff. It was the accumulation of the technologies. So the passive design and careful roof, wall and window choices keeps the house cooler to start with, the cool pipes improve the efficiency of the cooling system, allowing the cooling to be evaporative rather than a power-hungry compressor, allowing the evaporative unit (basically fans and a water pump) to be run from solar cells. Water is from underground tank storing rain from roof, thus cool. Result: cool house on 45C days, with no grid or mains water input. Capital cost of the cooling system was about $20K, or roughly twice a ducted airconditioner system, but the running cost is $0 compared to about $1000pa (it's really hot here).
Heating is a hydronic solar system in the slab. For temperature areas like Adelaide (annual minimum -5C) it works well. Cost was about A$15K, running cost is $0.
The near-off-grid design for a 12m x 20m suburbian block cost A$150k, compared to about A$100k for a conventional house. I'd say about $20k of that was construction inefficiencies that a wider use of the technologies would correct. My house is also smaller than a conventional house on the same block, since having eaves and shading implies less interior space. There is a great deal of usable semi-exterior space (the so-called "outdoor room"). I've been told be visitors that my new home is larger than the old one on this block. That's an illusion, it's just that every metre of the new house is a pleasure to be in (good natural lighting, temperature, etc).
Equiping the new house was difficult. About five years before the re-build I started buying appliances with an eye to their efficiency. If I hadn't have done that, then the evening wattage of the house would be about triple what it is. As it is, the house of four near-adults pulls less that 200W of an evening, with higher excursions as the fridge and freezer do their thing (although they do so much less often than a typical installation, since from beyond the doors they are in a sealed, foam-insulated cavity, fed from a cool pipe and exhausting directly outside).
I'd say the additional design -- if it were paid for, rather than done by me -- would be $20k. And that's the real problem. No developer wants to have an 'administrative cost' of 20% of a house's value. They'll always be undercut by Shonky Brothers. This is why regulation is needed. Market forces fail due to a lack of information -- it is only years after the sale when one neighbour pays $2000pa for energy and the other pays $0.
In summary: there is no technology which is a silver bullet. The silver bullet is a *system* -- a cooperating and self-reinforcing set of technologies and techniques, each of which contributes maybe 20% on its own.
I don't know anything about Europe, but there's no excuse for a domestic house in Australia to pull any energy *on average* from the grid. What we need is a regulation saying so, so the building development companies (which build most of the houses here in Australia) construct houses to meet that goal.
"Ground source heating is a rapidly growing technology that has the potential to produce at least 30 per cent of the country’s renewable heat needs"
I smell bullshit here.
1. Most new houses being built simply don't have the land required to stick one in, heck if it has a garden big enough to stick a barbie in, it's classed as a "executive" 5 bedroom house (3 bed in old money)
2. In highly populated areas, again you have issues. Tower blocks, houses that back directly onto public highways, shared ownership land, protected land etc etc....
Still ok for us that live in the sticks, but call me when I can get my money back in less than a few years, sounds selfish, but I'd rather pay £10k of the mortage and actually think about not having to worry if I can afford to go food shopping this week.
With -15 C outside I'm pretty happy to have a ground heat pump installed. At these temperatures it's taking an average of 1 kW to heat the house (200 sq-m) and enough hot water for four people.
The investment was about €17k, including a 150-meter deep vertical drill hole and the necessary plumbing, but not including the underfloor heating pipes (which would be needed regardless of the heat source).
I have recently installed my own GSHP. It is hardwork but easy for a good DIYer.
Cost of mini digger hire, pipes, coolant, heat pump, underfloor heating pipework and manifold but not installation was £5.3k (£6.5k less £1.2k grant from government).
It runs of a single phase supply (not three phase) and heats a 4 bed house for around £300 to £350 per year and there are no maintenance costs if you can read a gauge once a year to check for leaks.
Yes you do need to install underfloor, it doesn't work well (efficiently) with radiators and yes you do need a very well insulated house to go with it.
We are very happy with out system and believe it was only about £1k more expensive than an oil fired system and will pay back within 2 years.
... and it works really nicely. We had three 35m channels dug ~1.5m deep, a few metres apart and buried the coils in the back garden. These connect via a manifold to the heat pump itself in the utility room. That, in turn, is connected to the hot water system, and the underfloor heating system. We get all our space and water heating requirements fulfilled (5 bed semi) for around £100pcm - which compares well to the amount we were paying for LPG.
We could only do it because we already had the workmen in renovating the house, the back boiler had packed up and there's no gas in the village. It made sense to rip the old system out and get this installed.
Finding people who know how to size and plan for this kind of system is tricky, but I recommend the technology highly. It is an expensive retrofit and, as mentioned previously, there are many cheaper ways of saving money and making life more comfortable with insulation, draught-proofing, quality glazing, and attention to appliances.
Write a trivial story about a less than trivial subject and get 30 well informed comments for free. So, who at El Reg Towers has just bought a plot of land and is doing a new build? It's a tactic I use my self and don't mind seeing it here because I'm interested in the same stuff.
I thought Combined Heat and Power CHP was a useful thing to employ in the UK...
score another vote for air-sourced heat pumps here. You've also be well advised to hook in solar hot water, which is much cheaper and more efficient that PV, and produces useful supplementary heat even in gloomy Blighty.
one hitch with both schemes it that they both require you to fasten boxes to the outside of your house; the planning laws need to be amended so you can do it without the nimbys whining.
How much woud the cost of installations fall if the councils co-ordinated the installations?
Would it be worth a councils' while to dig up a their various properties (housing, parks, business properties) and use them to generate heat/electricity?
I assume that a large area such as a park could generate higher temperatures, so it would appear to make sense to make some use of the areas that we do have.
Just a thought - what about car parks and roads? loads of tarmac to absorb heat from ground and sun, since roads in particular get dug up on a regular basis it couldn't be that difficult to incorporate this sort of idea.
ttfn
We've had ours for four years and it is the best heating system we've ever had.
Land area is a consideration, but not as big as we had thought. The biggest part of the installation cost was digging the trenches for the collector coils - but this could be a DIY job, it's not sophisticated work.
You do need to attend to insulating the property, but that goes for any heating system.
An undefloor system is definitely an advantage, but modern heat pumps can run with hot side water temparatures of over 50 centigrade at good efficiency, so it's possible to use a combination of extra insulation and increased radiator size. Have a look at the manufacturers temparature differential vs efficiency curves.
Hot water is not a problem - ours delivers water at 50 centigrade plus, and will comfortably deliver enough of that to run a shower in "real time" - IE it can replace the hot water as fast as the shower uses it.
Add in the ability to use green electricity and the fact that the system is guaranteed for five years, has a rated life of 30 years and no servicing requirements (much better than boilers,because there's no nasty combustion, only a couple of rotary moving parts and all sealed).
You may need a three phase supply, but only for larger units. It's actually quite cheap to get that - somewhat to our surprise.
BTW, the comment about ground loops freezing is irrelevant - that's why they are filled with antifreeze!
Difference between gas and gshp is £190 a year. So say it costs you the least amount for the installation. Assuming no repairs whatsoever, it'd take THIRTY FIVE YEARS to break even compared to running gas. If you're looking at the top end of the installation cost, you are looking at a SEVENTY YEAR period before breaking even. Obviously these are variable depending on the cost of gas. You're still going to need a gas boiler anyway to top up what it can't supply. And as the climate changes, are you actually even going to need it?
Yet another "money saving" idea pumped by the eco-mentalists which doesn't actually save money.
There's a big IKEA store being built near to where I live here in Finland, and they're fitting it with ground source heat pumps for heating and cooling (yes there is an occasional need for that, too). They have something like 300 vertical drill holes, 200 meters each.
I'm not a big fan of IKEA (never bought a piece of furniture from them), but I trust that those guys are pretty good at calculating return on investment.
four of these went in during a house refurbishment. (Mitsubishi heavy industries SRK20ZGX-S.)
They're almost completely silent, and she now does all her cooking, hot water and everything else with electric.
In the six months May 28th to Nov 28th her house used on average 15 units per day, for everything.
I was so amazed, I did some experiments, and it turns out, one of these things could heat the house on its own, if the layout of the rooms had been different.
As a result I bought two more for my own house, this time SRK20ZIX-S. It's a solid wall, five bed, detached 1920s house. One pumps hot air along the upstairs corridor, and the other does the loft room (it was for cooling.) The one on the upstairs heats all five rooms and three bathrooms, because of the air circulation. The corridor acts as a big plenum chamber. It's off for all but three hours a day, and runs at 7 watts on standby, and 1327 watts absolutely flat out. The thermal capacity of the house keeps it going. Also, any heat in the top part of the house has reduced the boiler load. (Newton's law of cooling.)
As a result, I've range rated my vaillant boiler down to zero (10.4 KWs,) and it still heats the house, water etc without any upwards modulation. I'm now waiting for Baxi to end their agreement with British Gas, as I wouldn't piss on them if they were on fire, with their Ecogen. My gas bill's basically halved.
Modern ASHPs are ludicrously amazing. They are in league with lucifer.
Wrong. In highly populated areas, you have opportunities which are not available in low population density areas.
E.g. in a big block of flats you use small scale combined heat and power to provide locally-generated electricity and use the 'waste' heat for heating the hot water and (if necessary) the building. The difficulties in doing this are not technical, they are commercial and political, but other countries (notably in my experience, Germany) make district heating work.
But what is going to happen when the centre of the Earth inevitably gets colder due to people pumping out all the heat stored there?
Will your heat pump suddenly start extracting less heat once your neighbours get one installed?
Or will the Earth's liquid core solidify, rattle around for a bit like a walnut in its shell and eventually burst through the fragile crust?
"Yet another "money saving" idea pumped by the eco-mentalists which doesn't actually save money."
Actually it does, as has been proved in the Scandinavian countries for many years. That must smart somewhat, eh?
On the other hand, the UK energy sector depending on domestic and industrial inefficiency for it's profit isn't that smart at all.
Along with a fully airtight inner and outer chell, tripply glazed windows specifically designed to eliminate thermal leak paths, lots of insulation and filtered and heat exchanged air circulation system.
This is the house that does not *need* a central heating system.
c15k built in Germany.
0 built in UK.
Nuff said.
I looked into this idea as an add on to my existing home.
$25,000 (USD)
that is not economical - especially not as a one time cost.
let do some maths (I know they are hard).
Propane (the fuel for my heating system) is roughly $2.70/gal
Electricity (hot water in my home is heated this way) is $0.07/kwh (delivered and taxed)
I use around 400gal propane a year = $1080
I use around 5000kwh a year (entire house) = $350
total $1430/year
so - *IF* - GCHP zeroed all my utility costs (it wont) it will take roughly 17.5 years to pay back.
if we assume a more reasonable (and more likely) reduction of 50% in utility usage then the above payback becomes 35 years.
Current - govt incentive programs give me $2000 towards such a system. That reduces payback costs to 16 years 1 mon at complete utility replacement, and 32 years 2 months for 50%.
This of course does not take into consideration any interest that accrues during the payoff period for the GCHP (loan from the bank), nor any lost increase in value if instead the $25,000 was invested.
I am afriad the technology for a GSHP is very simple and reliable but because you have to buy a certified system from a certified supplier to get your ~2K government handout, all of this certification effectively doubles the cost.
So ~10K to 15K for a uncertified system or 30-40K for a certified system and supplier and you get 2K back from .gov.uk. not exactly a saving is it?
IMHO Just another nasty money making scheme for some .gov.uk cronies, making what could be a seriously good idea just insanely expensive for the rest of us.
I put in a geo unit in my house as new construction. You're right that the cost adder was about $25-30k, but that's to heat a house with about twice the square footage as my old house and to keep it about 7 degrees warmer in the winter (72F vs. 65F). Your heating costs seem pretty low as does your electric usage (400kWh/month?!). If your energy demands are truly that low you should be able to get by with a much smaller and cheaper system than $25k or go with an air source heat pump and eliminate the expense of the wells.
Search for "MicroCHP" to get a look at a few alternatives. The Whispergen unit from the New Zealand interests me from a grid viewpoint (I'm an E&U analyst with an international SI, not affiliated with Whispertech). It's a Stirling engine with a low floorspace requirement.
There are a number of ways to look at one from an overall energy usage standpoint. Feed it with gas and you'll dump about 5.5kw into your hot water system and about 800 watts into a battery system (you could run your house lights fairly comfortably on 12V with this, more bits with a bit of electrical plumbing).
With a Stirling, it's the difference in heat you're tapping, not just the heat from commercial fuel. With a bit of creative plumbing you could drive the motor from one of these from the difference in ground well vs. the air alone, and drive the generator directly from that.
As-is, it may not be hugely powerful from a size vs. output perspective (relative to say, a petrol engine) but there's a certain attraction to the concept of completely fuel-free operation.
Rather than heat the hot side heat exchanger with gas or diesel, you simply bury the cold side heat exchanger someplace colder than the ambient. The bigger the temp difference, the greater the power.
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