UPDATED: Air Source Heat Pumps/Air Con - Full Info & Guide, is it cheaper to run than mains gas?

paceinternet

Have you run the domestic hot water at less than 55, or does that help meet your maximum demand from the tank?

rhubarbe

No, we just run it at the setting it was installed at, which was 55C. That temperature works well for us and so far the system is working well, even in the rcurrent cold snap.

albyota

bobmedley wrote: »

Albyota

I have three aircon/heat pumps already used in conjunction with oil CH and am seriously considering canning the oil boiler when this tank runs out (various reasons - cost of oil, we've had a serious leak that cost Norwich Union a lot to clean up, boiler getting noisier through age etc).

I'm not totally convinced by the HT heat pumps, as in the Sanyo won't be big enough at 9kw (and my air-con man says that CO2 systems run at monster pressures so if anything goes pop it could be 'interesting') and I've seen mention that the Daikin has a compressor in the indoor unit that can be overly noisy. That means I would be looking at the 'standard' circa 55c heat pumps.

Anyway, I have a 300 litre unvented tank that is emptied completely every morning as the five of us get showered, and the oil boiler can get the hot water replenished within 10-15 minutes.

So - eventually! - the question is, how good is your Ecodan at heating water when there is a high usage?

Hi bobmedley, there is more than one way to provide a solution for any size house. from biavalent connection using ASHP with oil or gas boiler, multiple units with large thermal store, dedicated systems for hot water only or heating only.

It all depends on the application. it is true that the Daikin Altherma HT (80 degrees) has an internal Hydrobox...not that noisy, not an issue if it can be sited on a ground floor utlity room, basement or garage.

Sanyo at 65 degrees is also very good equipment, the refrigerant....well.... CO2 is hermetically sealed in the outdoor unit, and although higher pressures, these systems have been installed all across europe without a problem.

If your house is well insulated with DG etc... you need to get an up to date heat load calculation done...don't just go by the size of your existing boiler's output.

sized correctly, any of the systems can recover the hot water within 45 minutes.

by the way....the MHI air to air heat pumps you have just purchased will reduce the heat load of the house.

mitchy74

Some of the lads on here may be able to advise with this, as the Energy Saving Trust were useless.

At present I have a 3 bed 1.5 story timber built house supplied by LPG in central Scotland, the ceiling insulation is around 200mm and it has kingspan under the ground floor as there is a large crawlspace there. I have planning permission to add 2 extra bedrooms and 2 public rooms. (can supply the pdf pics if that would help). My Electricity is with EDF on a 8p a unit charge.

I currently have a year old 32kw LPG Worchester Boiler that supplies 10 radiators around the house and no hot water. (there is a 200l tank but I never bother with it and that function is turned off as I have an Electric Shower and Dishwasher). The heating comes on for 3.5 hours a day to take the edge off the house, 1 in the morning, 1 early evening and then the remaining 1.5hrs around 8pm. Last years spend was in the region of £2k on LPG and the house was never warm despite it being backed up with a log fire in the living room. When I bought the house the boiler was 15years old and I was told by the plumber that it was highly unefficient and I would see 70% improvement if I got a new one..... I havent seen any improvement, probably worse off.

The radiators are all fed through the thin copper pipe which looks like spaggetti under the floor (and under the kingspan) and has no insulation round it. As the boiler was bought on the understanding that the extension would happen its probably too big for what its currently supplying and there will be an eliment of loss using it.

On the basis of the above, would an 8.5 ecodan system be sufficient for my needs to heat the house and future extension and also now provide hot water via my existing tank and existing radiators using a wet system? I would replace the current copper pipe under house supplying the downstairs rads with thicker and insulate it but cant access the upstairs ones. I would retain my existing LPG boiler and tank as a backup as no point in getting it taken away and the £1500 boiler being scrapped.

Hopefully by changing I will get some sort of saving but just cant sustain paying £2k a year on LPG and still be cold.

Also the EST couldnt tell me about the Scottish incentives for going with a Air Source but any future payments from the Scottish Exec would be a bonus.

rhubarbe

We had LPG. It's a right b4stard, isn't it? Every time you phone up for some more (we were on 46kg propane bottles) they gleefully told us how much it had gone up.

Last year we ran out in February but there was no way we were buying any more LPG. We too had a log/coal fire. We had alos had electric underfloor heating.

So, last year:

LPG £500 (up to February)
Electricity £900
Coal £600
Wood 3000Kcal per hundredweight

We had an 8.5kW Ecodan installed in April.

So far we haven't managed to use more that 158kWh electricity in a week (and our base is 50kWh without any heating on at all).

No coal, no LPG, no wood, no electric underfloor.

I think that you may have a problem with the microbore heating pipe and I think your house sounds a bit bigger than ours (900ft2 detached bungalow) but our 8,5kW Ecodan heats ours with plenty to spare so I recommend getting a proper heat loss calculation done.

mitchy74

rhubarbe wrote: »

We had LPG. It's a right b4stard, isn't it? Every time you phone up for some more (we were on 46kg propane bottles) they gleefully told us how much it had gone up.

Last year we ran out in February but there was no way we were buying any more LPG. We too had a log/coal fire. We had alos had electric underfloor heating.

So, last year:

LPG £500 (up to February)
Electricity £900
Coal £600
Wood 3000Kcal per hundredweight

We had an 8.5kW Ecodan installed in April.

So far we haven't managed to use more that 158kWh electricity in a week (and our base is 50kWh without any heating on at all).

No coal, no LPG, no wood, no electric underfloor.

I think that you may have a problem with the microbore heating pipe and I think your house sounds a bit bigger than ours (900ft2 detached bungalow) but our 8,5kW Ecodan heats ours with plenty to spare so I recommend getting a proper heat loss calculation done.

Yeah the plumber assured me the pipe was fine but I just cant see where else the problem could be. Im assuming the boiler is heating water but it can only send so much round at a time given the thickness of the pipes....... the furthest away radiatiors are no sooner warm than they go cold again.

With the EST lot they did all these calculations of potential savings etc but, and not wanting to sound harsh, it was a young girl that came out and couldnt tell the difference between feet and meters on her measuring tape so I hold little hope.

So for an Ecodan 8.5 I would be looking at around £7k I assume fitted? provdied I dont need new radiators just pipes?

rhubarbe

Ours was £5500 including commissioning and a new 150L McDonald Engineers Powerflow2000 (I think they now do an EcoFlow for heat pumps). You need to use an MCS Registered installer in order to qualify for the Renewable Heat Intiative Feed in Tariff payments that are supposed to start in 2011 (under review since the Spending Review) and you'll need an MCS registered installer to get hold of any grants going. Our grant came from the Low Carbon Buildings Trust but you'll need to have a look at for yourself in Scotland.

We had quite a few quotes but the ones that were MCS registered all wanted a lot more money than the ones that weren't.

The only one that didn't was these people: http://www.acsrenewables.co.uk/ though they are based in the Midlands I don't know if the cover Scotland - worth a call though. They were excllent in every way.

mitchy74

Just had my quote through, apparently I need 2 * 8.5kw Ecodans with the total cost of materials/comissioning but excluding fitting around the £14k mark from IceEnergy! Bit of a surprise.

Annoyingly though just spoke to another installer who is saying that he thinks I would need 20kw and that he wouldnt recommend Air Pumps due to having the microbore piping.

Cardew

mitchy74 wrote: »

Just had my quote through, apparently I need 2 * 8.5kw Ecodans with the total cost of materials/comissioning but excluding fitting around the £14k mark from IceEnergy! Bit of a surprise.

Annoyingly though just spoke to another installer who is saying that he thinks I would need 20kw and that he wouldnt recommend Air Pumps due to having the microbore piping.

Wow - the RHI will need to be huge to justify that sort of expenditure.

mitchy74

Apparently £2k per year on that and the saving of £1100 per year on the LPG less the increased Electricity.

No idea how they calculate it, dont have enought knowledge on these things so could completely get led up the garden path.

Looking online at the Airconwarehouse website the 8.5kw package there seems to come in at £5100, which still works out cheaper if you double up despite probably not needing double of everything.

Probably easier just to sell the house.