We're about to embark on updating a 1970s bungalow, which currently has storage heaters and a hot water cylinder plus immersion heater, all assumed to have been there since it was built. One thing is certain: we want to change this. Options we've been pondering:

1. Air source heat pump plus wet underfloor heating (plus solar thermal possibly, but might have to be later for financial reasons). Pros seem widely known, but cons for us are: it's in a conservation area and AONB, so planning might be refused (also, planning will add 2 months before we can get started, which isn't ideal); also, we're concerned about the noise as the village is very peaceful, and neighbours aren't far away as it's a small plot.

Ideas/questions: is it feasible to put an ASHP (eg Mitsubishi Ecodan) in the garage (adjacent to property and near the kitchen)? I've read such conflicting accounts: some people say they have them running in a loft or garage fine; others say there's not enough airflow and the unit will freeze too quickly (plus creating a cold room will suck heat out of the main house anyway).

Also: is there something that can be installed (electric boiler? or just use immersion heaters?) in place of an ASHP while planning permission was pursued, and then swap one in later? Still worried about noise and neighbours though.

A problem with wet UHF here is that it may add too much height to the (concrete) floor.

2. Bog standard gas combi and rads (or wet UHF). Presumably cheap to run and reasonable to install. Cons: property not connected to gas (am seeking quotes for the price), and needs flue etc. I'm not keen on gas and am fairly convinced prices will rise a great deal in years to come; and it's a finite and dwindling resource anyway.

3. Wood burning stove with back boiler (plus rads or wet UHF). Nice, but: property has no chimney, so needs a flue put in (planning permission probably needed in this area). Price of stove and flue work quoted is north of 4 grand. Also, would need to give up valuable storage space for wood. I assume wood pellet boiler would be too expensive for us.)

4. Modernised electric system: dry underfloor heating, and a heat bank with immersion heaters plus (now or as soon as we can afford it) solar thermal to help with DHW. Now, yes, I do realise electricity is expensive and not thought of as green, but we use a 100% green tariff so in fact we'd have a tiny carbon footprint. But, er, maybe a huge electricity bill? Obviously we'd need to optimise our production/use of DHW.

Obviously whatever we do (esp. 4) we'd insulate to the max - walls, floors, pipes, tanks, double glazing. Sorry for the long ramble - just very interested to hear people's thoughts and advice. Have we missed another solution? (Perpetual motion machine?) Thanks!

Insulate first -- if you do it really well then no formal heating system will be needed

Solar hot water is a good idea.

perpetual motion wouldn't help as removing energy from it would slow it down till it eventually stopped

my boreholes were only 9.5m deep but cost £240 each!!! they werent for heat pump thogh, are you sure that you need to go 100m deep?

Insulate first, then do some calculations on how much energy you can save that way, and then insulate some more. When you have done that keep adding some.

You could embed some renewables, thinking mainly solar, PV and Thermal if your budget runs to it. I worry about pellet boilers because of the volatility of pellet prices.

Tony.
GSHP bore holes are deep to get enough surface area of pipe in contact with the ground more than anything magical happening down there, why horizontal slinkies are only a couple of meters deep but still about 200m long per loop (probably teaching grandmother to suck eggs here as you have more experience than me on these things).

Perpetual Motion, surely crystals spinning inside some magnets will work with a side benefit of some kind of quantum effect (or is it affect) cleaning the air of nasties and getting rid of limescale. Make sure the housing is a pyramid otherwise it will never work.

Posted By: gustyturbineIf your ground temp drops then COP drops and system fails.

It's not so much that the COP drops with temperature, it's more that the capacity drops. There's only a small difference in COP between ground at 0C and ground at 8C but a much larger capacity change. It's always worth doing some calculations though as having a borehole deeper than necessary is a sunk (pardon the pun) capital cost that will never pay back. Of course, going too shallow will have a cost in backup heat - you have to factor this versus the cost of the extra drilling.

Paul in Montreal.

What about a ground-water-source heat pump? This requires two boreholes, but they only need to be deep enough to reach the water table, so the cost depends on how close to the surface the water table is.

Water is pumped up from borehole 1, has heat extracted from it (at a better CoP than ground source), then is pumped back down to the water table through bore hole 2.

Not all makes of heat pump support this option. Viessman do, but they're not cheap. I know there's at least one cheaper brand, but can't remember what it is.

Posted By: markdeardenWater is pumped up from borehole 1, has heat extracted from it (at a better CoP than ground source), then is pumped back down to the water table through bore hole 2.

In theory, the COP is higher (due to bigger effective collector area and no dip in borehole temperature) but, in practice the COP and operating cost are often lower. The COP is lower due to the power the pumps that are required to extract the water consume - this is way more than circulating water in a closed loop. Second, the operating costs are higher due to the need to de-mineralize the heat exchanger in the GSHP every so often. Of course, if you have an artesian well, it's easier - but in many places it's impossible to get permission to "dump" the water that's been extracted.

Paul in Montreal.