Can I ask for some advice here, as a rapidly learning novice.

We're buying a house in the north of England, 1000 feet up in the Pennines - a mix of solid stone and cavity insulated walls, about 190 square metres. Currently it's heated by a coal-fired stove powering radiators, and that's going. Question is, how do we heat water and space.

GSHP impossible due to configuration of land. No mains gas, obviously. Planning permission unlikely for solar panels (we're in an AONB). We looked at wood-burning systems, but we don't have anywhere to season wood, and the level of hard labour required makes it impractical. Wood pellet systems are prohibitively expensive to run. So we were thinking that, like everyone else around there, we were going to have to fit an oil tank and have done with.

Then we came across this business of _air_ source heat pumps. What we're thinking of now is the following:

- Panasonic make air-to-air heat pumps, which they claim blow warm air around your house enough to heat it adequately. I've used air-duct heating systems in the US and have no problem as such with them. What makes me nervous is (a) their claim that one or two such units can effectively heat a whole house; (b) are they going to make so much background noise that I go postal; (c) can they really extract enough heat from the northern English air? They claim that they can function without backup as long as it is more than -5 degrees outside, which (if true) covers enough of the year to be able to manage with a wood-burning stove and electric radiators for the rest of the time.

- And the 'Altherma' system which is being marketed in the UK by Daikin claims to be able to use an air-to-water heat pump to be able to provide domestic hot water, with an immersion heater backup for heavy usage / very cold weather. That seems more straightforward, but again I don't really know if it can do what it claims. Nor what it costs (they are very cagey about that).

All this seems very appealing, both in carbon-footprint terms and in reducing running costs. And since I have to shell out to fit a new system of _some_ kind this year, it seems an obvious opportunity. But I am nervous about being an early adopter of something which is obviously very new in Britain.

Can anyone reassure me, or warn me off?

Thank you!

Air source heat pumps are apparently very popular in Scandinavia. Viessmann also do a warm air system. There are systems out there that can be attached to radiator systems, but I would suggest that the radiators are sized to account for the lower heat output - around 40 deg compared to 80 deg in tradiational systems. If you try contacting GSHP companies, you'll eventually find someone who does air source heat pumps for homes. Mitsubishi Electric do a product too.

Regarding the technology - look around at offices. The air conditioning units on the outside are quite often heat pumps. The addition of the capability to produce hot water is only difference between those and what you'll be looking for.

Hi Paul, Why did you dig to 130 metres, clearly the further down you go the hotter it gets, the hotter the water that comes up the more efficient the heat pump would be, so did you stop there?
Are there practical barrriers to going down further, or just cost
any other hints about doing it in Wales

<blockquote><cite>Posted By: chrisslader</cite>Hi Paul, Why did you dig to 130 metres, clearly the further down you go the hotter it gets, the hotter the water that comes up the more efficient the heat pump would be, so did you stop there?
Are there practical barrriers to going down further, or just cost
any other hints about doing it in Wales</blockquote>

Hi Chris, the length of pipe will be worked out by the heat requirement of the house. From this, and knowledge of the underlying geology, you can work out what length of pipe you need on the send and return to pick up enough heat out of the ground to heat your house at min outside temperature. Somewhere around 150 meters is fairly standard. If you need more heat the tendency is to go for more boreholes. What you need to not mix up is a geothermal system - like they'd have in iceland, where is does get proper hot when you start digging deeper. In most part of the UK under the ground is a nice steady temperature, somewhere under 15 degrees (I think about 12!).

To Alec - the original poster, I've heard reports that airsource pumps are horrendously expensive to run, when it's cold outside. I.e the time you need them most. This is because there's less heat in the air and so they run less efficiently. A guy on a training course I did had a full SAP assessment done on his house comparing running costs for an ASHP and a Gas combi. Heat pump was at least double (can't remember the actual costs - it could have been 10 times as in a magnitude higher). But you should consider a bore hole driven GSHP. The hole will cost a lot though. Been trying to find out a cheap way to get this done in an urban environment. The best idea is to get all my neighbours to do it at the same time, so we only need one survey and move the rig down the street as he finishes off the previous job. Just about to move house, so will write back one day if I'm successful!

Simon

Has anybody come across this product:

http://www.genvex.co.uk/genvex-air.asp

I spoke to the gut at Genvex about it and was quite convincing, (I suppose they always are), its priced at about the cost of they're higher end MHRV units (£4k+) and would seem to do away with the need for gas, especially if paired w/ solar thermal and or wood burner. In a AECB Silver+ standard house (for insulation + airtightness).

Has anybody any views / advice... in terms of energy /economics...?

On other attraction was that even if it only limped its way through cold winters the stove/solar could be added post completion to spread the cost of services on the project as long as provision was made.

J

Simon, the best way to future proof would be to design out the heating system all together by installing high enough levels of insulation. With 20 years to play with you can afford to spend now on this even on borrowed money and never have to pay for space heating or maintenance of plant of replacement. Solar hot water is a must and may be pvt too. Look forward to the findings and questions.

Well designed solar will make water warm enough for showers even on many cloudy days. I would suggest a very much larger store and then there would only be a problem for prolonged cloudy periods when a back up heat supply could be used.

400l solar store for HW possibly as a pre heat arrangement with 120l available at 55 most of the time. Evac tubes would be nice but not completely necessary as even a good sized ( 6m^2) diy panel will do.

MHVR is a must and super low air leakage. NOT passive stack. If u insulate really well you should not need a heating system and on the coldest days couple of weeks a year some heat can be added to the building anywhere even inside the MHVR to cope. Then the thermal store idea may be not needed.

'Thing is, if I'm able to design out most of the heating load, so don't need the air to water for heating but I've still got the DHW load (particularly on cloudy winter days) to take care of, the Genvex system seems to be saying that for the same price as the MHRV system I'm paying for anyway I can have a system that ditches the boiler, (and therefore ditches also the need for a mains gas connection? ££ ?)...

...but then again what do we know about things that seem too good to be true... (they useually are!).

J

To say that you will never recover the capital cost is difficult to believe because there must come a point when it will have paid for itself even when lined up against a heat pump. They could try arguing that it would take four times as long and that by that time we might not be here any more but even then there will still come a point when it will have paid for itself.

Elsewhere in this forum someone mentioned suggested the Trianco ASHP. It is worth looking at the Trianco Web site. They are going into ASHPs as oil boilers are a dying breed.