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

Edale

Well I have read it again and I agree it is not clear. I still think it will be calculated as I said previously. I think the document implies they want to subsidise based on a 20 year life but pay it over the first seven years,this is achieved by an increased tariff than would otherwise be paid over 20 years.

If you look at points 133-135 in the document about what the tariff is trying to achieve, they are trying to get the tariff to pay for additional up front costs and 7.5% for financing costs. On my system I probably spent an extra £5k the tariff as you calculate it would give me nearly £5k per annum for 7 years which is far more than the document suggest. If it were calculated as I suggest, the payment will be around £1500-£1700 per annum which will achieve their objectives of paying my additional up front costs and also 7.5% financing costs.

grahamc2003

Edale wrote: »

Well I have read it again and I agree it is not clear. I still think it will be calculated as I said previously. I think the document implies they want to subsidise based on a 20 year life but pay it over the first seven years,this is achieved by an increased tariff than would otherwise be paid over 20 years.

If you look at points 133-135 in the document about what the tariff is trying to achieve, they are trying to get the tariff to pay for additional up front costs and 7.5% for financing costs. On my system I probably spent an extra £5k the tariff as you calculate it would give me nearly £5k per annum for 7 years which is far more than the document suggest. If it were calculated as I suggest, the payment will be around £1500-£1700 per annum which will achieve their objectives of paying my additional up front costs and also 7.5% financing costs.

Agreed - the stated objective of the rhi wouldn't be met if the repayments were as have been calculated on this thread - but the calculations were to the interpretation I made. In fact, if it weren't for the breach of the overall objective, I'd say my, and others, interpretation was correct. It's poorly written imv due to this ambiguity.

I think the thing about the tariffs is that they may (as Edale implies) already include the 'up front' or brought forward or accelerated payments, so the tariffs over 20 years would be 7/20 of the published tariffs, which seem to be (but not explicitly stated) to have been calculated for 7 years (and not 20). It's not clear to me what the real proposal is, and overgenerous payments have been made in the past and, indeed, currently are for the commercial rhi (which is metered, so an incentive there to waste heat!). Also, it may be that to incentivise smaller installatons, bigger installations on the same rate get large payments - I wouldn't rule anything out atm. Also, remember most are on the gas grid, so don't qualify for these payments. Which leads me to a question - I'm not on gas, but there is gas available closeby should I want it. Anyone know if I qualify (i.e. is the rhi (for air to water heatpumps) available only to those not connected to the gas grid, or only those without the possibility of being connected?

The poor guys writing and reviewng these documents are probably only being charged out at 3 grand a day, so we shouldn't expect perfection in their documents, proposals and modelling!

grahamc2003

Here's an extract from an installer's just updated website....

Using the average ASHP tariff of 9.2p/kWh you would receive an annual payment of approximately £2,661 each year for 7 years. .....'s 9kW system can be installed from £6,499 incl. VAT. Not taking into account of the fuel savings this will give a payback period of less than 3 years.*

zeupater

grahamc2003 wrote: »

Agreed - the stated objective of the rhi wouldn't be met if the repayments were as have been calculated on this thread - but the calculations were to the interpretation I made. In fact, if it weren't for the breach of the overall objective, I'd say my, and others, interpretation was correct. It's poorly written imv due to this ambiguity.

I think the thing about the tariffs is that they may (as Edale implies) already include the 'up front' or brought forward or accelerated payments, so the tariffs over 20 years would be 7/20 of the published tariffs, which seem to be (but not explicitly stated) to have been calculated for 7 years (and not 20). It's not clear to me what the real proposal is, and overgenerous payments have been made in the past and, indeed, currently are for the commercial rhi (which is metered, so an incentive there to waste heat!). Also, it may be that to incentivise smaller installatons, bigger installations on the same rate get large payments - I wouldn't rule anything out atm. Also, remember most are on the gas grid, so don't qualify for these payments. Which leads me to a question - I'm not on gas, but there is gas available closeby should I want it. Anyone know if I qualify (i.e. is the rhi (for air to water heatpumps) available only to those not connected to the gas grid, or only those without the possibility of being connected?

The poor guys writing and reviewng these documents are probably only being charged out at 3 grand a day, so we shouldn't expect perfection in their documents, proposals and modelling!

Hi

Applying a calculation based on a solar thermal system costing a nominal £5k which is MCS assessed as supplying around 1000kWh.t/year ...

Deemed 7 year
Option 1 - 1000*0.173*7 = £1211 Total / 7 = £173/year
Option 2 - 1000*0.173*20 = £3460 Total / 7 = £494/year

Looking at it a different way ... the commercial payment is 8.5p/kWh.t for 20years on systems up to 200kW.t simply applying the 8.5p over 7 years would result in a tariff of 24.3p (8.5*20/7) ... it would be logical to suggest that the tariff/kWh.t would be higher for smaller domestic systems when considering additional capital investment allowances etc which would be available to commercial enterprises and economies of scale applicable to larger installations ...

HTH
Z

grahamc2003

zeupater wrote: »

Hi

Applying a calculation based on a solar thermal system costing a nominal £5k which is MCS assessed as supplying around 1000kWh.t/year ...

Deemed 7 year
Option 1 - 1000*0.173*7 = £1211 Total / 7 = £173/year
Option 2 - 1000*0.173*20 = £3460 Total / 7 = £494/year

Looking at it a different way ... the commercial payment is 8.5p/kWh.t for 20years on systems up to 200kW.t simply applying the 8.5p over 7 years would result in a tariff of 24.3p (8.5*20/7) ... it would be logical to suggest that the tariff/kWh.t would be higher for smaller domestic systems when considering additional capital investment allowances etc which would be available to commercial enterprises and economies of scale applicable to larger installations ...

HTH
Z

I'd say that both of those rates are possible and not out of line depending on what the proposal means. Do you think one of them is out of the question for some reason?

As to applying logic- well that's fine for maths and philosophy, but not really applicable to what politicians in general, let alone the dept of climate change, decide, imv. I'd say the more illogical the better as far as decc is concerned (the whole process is about paying higher grants to the most inefficient methods, less to more efficient, and nothing to the most efficient methods!).

zeupater

grahamc2003 wrote: »

I'd say that both of those rates are possible and not out of line depending on what the proposal means. Do you think one of them is out of the question for some reason?

As to applying logic- well that's fine for maths and philosophy, but not really applicable to what politicians in general, let alone the dept of climate change, decide, imv. I'd say the more illogical the better as far as decc is concerned (the whole process is about paying higher grants to the most inefficient methods, less to more efficient, and nothing to the most efficient methods!).

Hi

I think that the issue is really with the BRE (and/or installer) and the calculation for the EAG (Estimated Annual Generation) for various RHI technologies.

As such I was attempting to convey that whichever calculation is used against the MCS EAG it wouldn't cover a typical buy price for a solar thermal system, which brings the generous potential payments for heatpumps which have been mentioned on this thread into question ... I would suggest that the issue will potentially lie more with the installer's calculated/declared EAG than the actual tariff ....

As I see it, the likely reasons would be ....

(i) The BRE & DECC have completely screwed up on their calculations regarding heatpumps.
(ii) The installers have based the EAG on the sizing-calculation (maxdemand) heat output of the system, not the estimated demand of the property ...
(iii) The calculated heating demand of the property is based on a poorly-insulated state.

My best bet ... the BRE have provided DECC with a calculation which describes the displaced carbon-source energy which takes the COP into consideration and DECC in their infinate wisdom have applied the COP multiplier again, thus creating a figure which will payback a multiple of the installed price which equates to the typical COP of that technology .... if so, expect the 20/7 calculation to be the correct option and a correction to the heatpump tariff or calculation ....

All conjecture, but time will tell .... and if not I'll be looking for an installer next year too !! ...

HTH
Z

nande2000

Begrudgingly i'm looking into doing a retrofit (rads) of an ASHP on a 1960s house. It has cavity wall insulation, double glazed and new loft installation was put in 3 years ago (was up to the spec as of then).

I've spoken to a few installers already; everybody is pushing the Ecodan. One installer did advise against me putting ASHP in and advised a new wood pellet boiler instead. All of the installers agree my heat loss requirement is between 8.5 and 9 kw. Most of them are advising a 14kw unit; one installer advises an 8.5 kw unit and topping up heat with log stoves that I already have, he said a 14kw unit would cost more than my oil boiler currently does to run !

It is a minefield, but ASHP must have a part to play in retrofit properties, but what is it ? Should I really go for the small unit; attach it to a thermal store and link in a log stove to get high temps for my rads ?

[Deleted User]

nande2000 wrote: »

Begrudgingly i'm looking into doing a retrofit (rads) of an ASHP on a 1960s house. It has cavity wall insulation, double glazed and new loft installation was put in 3 years ago (was up to the spec as of then).

I've spoken to a few installers already; everybody is pushing the Ecodan. One installer did advise against me putting ASHP in and advised a new wood pellet boiler instead. All of the installers agree my heat loss requirement is between 8.5 and 9 kw. Most of them are advising a 14kw unit; one installer advises an 8.5 kw unit and topping up heat with log stoves that I already have, he said a 14kw unit would cost more than my oil boiler currently does to run !

It is a minefield, but ASHP must have a part to play in retrofit properties, but what is it ? Should I really go for the small unit; attach it to a thermal store and link in a log stove to get high temps for my rads ?

Can only think you may be better off with the 14kw come winter as you are on rads though no doubt the smaller unit will do perfectly well if connected UFH. In saying that you have a lower heat demand than us.

As you have PV why not install the Immersun so your PV will heat your hot water the bulk of the time instead of the EcoDan? That will save loads as unlikely you are utilising the PV investment to it's max.

Just for interest Our 14kw Ecodan consumes roughly 6500 units per year for heating and hot water in a large 100 odd year old house. Thats approx £600 at our leccy rate. Hopefully our pending Immersun install will knock off another £150ish. Considering the Ecodan is never really off as has weather compensation etc I really doubt oil could get anywhere near this figure...

The Ecodan is a stunning piece of kit and probably the best out there. The wife loves it more than me :mad:

The only pellet boilers I've seen are in big country couses where they come into there own.

Had I gone down the rad route i would be looking at those triple rads.

John_Pierpoint

Let me know if /when you reach a conclusion - as I have a similar predicament..

Presumably ripping up the floors and installing insulation and underfloor (wet) heating is a non starter? So you need to go for oversized multi panel radiators and the dreaded immersion supplementary heater, for those sub zero winter nights?

Ground source heat pump has been ruled out on the basis of cost or ground space?

I would think that the log burner is suggested as a method of keeping the living room hot on winter nights as well a giving a cosy focal point. Using it to heat the water up to fossil fuel temperatures rather smacks of having a dog and barking yourself?

How goes your winter orientation for solar gain through those now illegally large 60s "sunshine" picture windows and presumably the thermal mass of the structure is limited to brick cavity clinker block 11" external walls and 4" clinker block internal walls, rather than timber stud work, or dense concrete blocks?

My mother had a house like the above (the blocks were lightened by diamond voids) - The new owner after she died, demolished it.

Anyone know of an on-line site where us consumers can enter the parameters of our properties and get an energy requirement - would be useful for playing "what if" games when evaluating further insulation, the key to these "new" eco technologies.

nande2000

jeepjunkie wrote: »

Can only think you may be better off with the 14kw come winter as you are on rads though no doubt the smaller unit will do perfectly well if connected UFH. In saying that you have a lower heat demand than us.

As you have PV why not install the Immersun so your PV will heat your hot water the bulk of the time instead of the EcoDan? That will save loads as unlikely you are utilising the PV investment to it's max.

Just for interest Our 14kw Ecodan consumes roughly 6500 units per year for heating and hot water in a large 100 odd year old house. Thats approx £600 at our leccy rate. Hopefully our pending Immersun install will knock off another £150ish. Considering the Ecodan is never really off as has weather compensation etc I really doubt oil could get anywhere near this figure...

The Ecodan is a stunning piece of kit and probably the best out there. The wife loves it more than me :mad:

The only pellet boilers I've seen are in big country couses where they come into there own.

Had I gone down the rad route i would be looking at those triple rads.

Hi, when is your heat pump programmed to be on and off to get those figures ?

Wood pellet boilers are far too expensive (if you want one to last longer than 10 years); the only other serious contender i can think of at the moment is a solid fuel / condensing oil boiler / immersun link up.