Off gas, ASHP or GSHP?

rpeckham

Hi

Can anyone help? I'm building a new house in an area with no mains gas. This will be a house for my family and I to live in for the long term.

Oil heating isn't really viable and I'm keen to use either GSHP or ASHP with solar hot water. The house will be timber framed with 90 mm Celotex (or could increase to 140 mm- please advise if you think worthwhile) but will only contain standard 4/16/4 mm glazing. There will also be 2 double-sided woodburners which offer the potential to heat 2 rooms each on the ground floor with flue ductings to upstairs to heat upper rooms.

We will have ufh on the ground floor and radiators on the first floor. Ideally I'd like the system to operate to provide continuous ambient heat of around 17 degrees and then be topped using the wood burners.

The house will be quite large, approx 350 m2.

Can anyone advise on the way to go? I'm advised that ASHP can be troublesome and ineffective when it is very cold. Alternatively if we use GSHP we will need bore holes. I'd also be interested in an estimate of the likely cost of a GSHP system (which would be my preference).

It strikes me that the entire system (including the house insulation) needs designing from a clean sheet of paper- if anyone knows of a company or individual or person with this capability that they could recommend I'd be very grateful.

Many thanks

Reuben Peckham.

sashman

4.16.4 glazing may not reach the new standards. If you have build reg approval then you may be able to comply to the regs at the time they were approved (uv2) but today replacements need 1.6uv or C rated. I would urge you to fit A rated, it is energy neutral. check out www.bfrc.org.uk for companies

sashman

muckybutt

Speaking from having had an ASHP...I wouldnt touch one with a barge pole !

We had one fitted the other year and it cost a bl**dy fortune to run, summer months with the average temp above 2 deg it worked a treat but who wants the heating on in the summer ?, winter months it left a lot to be desired. Last winter it cost £800 for 70 days use, now got rid of the blasted thing and got a multi fuel stove instead.

Hintza

We are getting GSHP fitted with ground loops, the company we are using is Anderson Floor Warming in Glasgow. We are having trouble getting the loops in the ground (doesn't stop raining). The cost for 150m2 house is £21,000 plus the loops which I am doing expected cost £3-£4k. To drill is about £40/meter (ie about £8,000).

Breakdown
£13,500 for heat pump (Nibe) + ancilliaries
£6,700 for UFH and radiators etc
£700 for odds and sods.


We ditched the solar hot water (£6,000) as project was going over budget (possibly regretting that now)

MX5huggy

Insulate insulate then insulate some more. Then you wont need heating. Apart form a wet dog and a 50 inch plasma.

Aim for a wall u-value below 0.2, roof 0.1, floor 0.1, windows 1.0.

rpeckham

Thanks for all your comments. I'm a little frightened by the cost of the GSHP system referred to in Scotland but it's obviously an investment for the long term (incidentally Nibe have been recommended to me as a Scandinavian make who are very experienced). Agree with the insulation too.

As for ASHP... many manufacturers claim good efficiency at -20 deg C and they have been used in Scandinavia where it is -10 every Winter for 3-4 months... can't understand this.

muckybutt

rpeckham wrote: »

As for ASHP... many manufacturers claim good efficiency at -20 deg C and they have been used in Scandinavia where it is -10 every Winter for 3-4 months... can't understand this.

The one we had, had good effiency ratings and still managed to kick out 54 deg last winter when -13 outside but it'll cost ya a fortune to run, not only does the ashp run flat out but the supplementary heater will be on constantly too.

If we were to do it again then we'd go for the gshp where its constant temp all year round.

henchard

I'm at a similar stage and have decided to go th GSHP route. But how do you find someone who knows what they are talking about? I'm relatively practical and aware of many of the issues but the more I look and ask questions the more confused I get with the answers. I don't mind paying for expert advice, but I do mind paying for poor advice from the cowboys who seem to have sprung up out there. At times it seems like the wild west.

So as I say how do I find someone (I'm based in south wales) who really knows what they are talking about (and doesn't have vested interests) when it comes to designing my Heating System?

deepindersomal

I think you have hit the nail on the head. how do you find someone who actually knows what they are talking about.
we have bought a new build house which was completed about 2009, but the oil fired boiler was in the basement and got wrecked because of flooding.
we are now looking at using GSHP for our heating and hot water.
We have had one quote to use a 18Kw pump with 2, 300 litre tanks and another to use a 25Kw pump. these were from suppliers/installers
we also got a specialist company of design engineers recommended by our architect to come up with their design , they came with a recommendation of a 45Kw pump which was going to cost over £70,000.
My feeling is they have way over specced the design to cover all eventualities and then some but any thoughts on what might be the size of heat pump needed for a large 450sq m house with 4 bathrooms.
the 1st 2 companies used heat loss figures of between 25 and 35w/m2 but the design company were using 60-70w/m2 for their heat loss calculations.
there is underfloor heating on ground floor with rads on 1st floor and basement
Any comments would be useful

Hintza

45kW pump...........:eek: Sounds a bit of overkill.

What was interesting is our architect got an engineer in to spec ours and I got my prefered installer to a meeting. After a bit of professional sparring they seemed to get on quite well and all was agreed.

Your problem is likley to be UFH or radiators (oversized)?


We are still having huge problems getting the ground collectors in the ground (never stops raining for long enough) and it is really holding the whole project up.

You really really need to find someone you can trust.

piggielady

We refurbished an old farm house in an area with no gas. We eventually decided upon a combination of a multi fuel burner which heats 7 radiators and hot water and modern efficient storage heaters. Large 3 ded detached house - elec bill £55 per month. Plus wood for burner, which to date has cost us nothing. You do need to be organised though to have a woodburner!!