Electric wet central heating options?

dekh

paceinternet wrote: »

Yes, your maths is terrible (or mine is).
2 kw for those hrs = 8736 kwh

That's what I missed

OK full heating system...

I talked to the Energy Saving Trust. I couldn't tell you which way they were biased but they wouldn't give a straight answer to the question "Is it worth swapping?"

There website figures are different to the ones they quoted. Here's what they quoted:

To install a 6KW ASHP which will provide 100% of your heating and 50% of your hot water it will cost from £7,000 to £10,000

It will cost approximately £320 pa to run.

No answer on warranty. So I can only assume 1 year.

Their site claims saving of £700 over electric heating.
£50 gas, £20 oil £460 solid fuel.

Their figures don't quite add up for me as if I were to replace my gas CH I would save a lot more the £50 if my total heating bill was only £320 per annum never mind the hot water boost and the homecare cover as well.

But even saving £700 per annum it will take 10 years to break even assuming no maintenance costs. No lost interest on £7,000 tapering off over 10 years. That on the cheapest install.

There is good news. You can get a grant for 30% up to a maximum of £900. Brings break even down to 8.7 years.

On the green side, no savings on Gas and Oil in CO2 emissions.

Does this make it only worth considering if you have no central heating system at all?

Cardew

dekh wrote: »

That's what I missed

OK full heating system...

I talked to the Energy Saving Trust. I couldn't tell you which way they were biased but they wouldn't give a straight answer to the question "Is it worth swapping?"

There website figures are different to the ones they quoted. Here's what they quoted:

To install a 6KW ASHP which will provide 100% of your heating and 50% of your hot water it will cost from £7,000 to £10,000

It will cost approximately £320 pa to run.

No answer on warranty. So I can only assume 1 year.

Their site claims saving of £700 over electric heating.
£50 gas, £20 oil £460 solid fuel.

Their figures don't quite add up for me as if I were to replace my gas CH I would save a lot more the £50 if my total heating bill was only £320 per annum never mind the hot water boost and the homecare cover as well.

But even saving £700 per annum it will take 10 years to break even assuming no maintenance costs. No lost interest on £7,000 tapering off over 10 years. That on the cheapest install.

There is good news. You can get a grant for 30% up to a maximum of £900. Brings break even down to 8.7 years.

On the green side, no savings on Gas and Oil in CO2 emissions.

Does this make it only worth considering if you have no central heating system at all?

There must be some misunderstanding on running costs here.

It is not possible to give a cost for running any form of CH/HW.

What I assume they are saying is you take a baseline of £1,000 for 'straight' electrical heating - say 10,000kWh @10p/kWh.

Therefore to produce that 10,000kWh of heating would take £320 with an ASHP(a COP of approx 3) £370 for gas, £340 for oil and £780 for solid fuel.

If you use 20,000kWh gas(about the UK average) then double all the figures above.

As I said earlier, at current prices IMO it would never be a paying proposition to replace gas or oil CH with an ASHP

Certainly in areas without access to gas, - particularly new builds - ASHPs are well worth considering. They are particularly suited to underfloor heating where the big disadvantage of heat pumps - namely low water temperatures - is not a drawback.

albyota

Cardew, as you are the resident proffessor of all and sundrie, and have gained respect from many, please have a look at the Sanyo CO2 ECO system, it might be useful to others readers if you could give a more informed opinion, these systems are being improved on almost by the week, there is no need to upgrade radiators, the EST website is totally out of date and, we in the industry get the feeling, they are under pressure to 'downsell', because if everybody had these installed the power grid would collapse, ............its not ready for this yet!! if my system has now saved me over £700 in almost a year, the OP is right to be confused by the conflicting figures.

Cardew

albyota wrote: »

Cardew, as the resident proffessor of all and sundrie, and have gained respect from many, please have a look at the Sanyo CO2 ECO system, it might be useful to others readers if you could give a more informed opinion, these systems are being improved on almost by the week, there is no need to upgrade radiators, the EST website is totally out of date and, we in the industry get the feeling, they are under pressure to 'downsell', because if everybody had these installed the power grid would collapse, ............its not ready for this yet!! if my system has now saved me over £700 in almost a year, the OP is right to be confused by the conflicting figures.

Thanks for the compliment. However I think paceinternet is far more of an authority on ASHP's than I and his posts always make a good deal of sense - ditto samtheman1.

Actually the Sanyo was discussed in the 'sticky' thread on heat pumps and this is what I wrote:

Had a quick glance at the SANYO CO2 and it makes a big play of getting the domestic Hot Water(for taps etc) to 65C but doesn't say what the CH water temp will be???? admittedly with your new installation with underfloor heating that won't be an issue.

It also(unless I missed it) doesn't give in detail the COP at various outside ambient temperatures.

There surely must be a 'downside' in enabling it to produce water at 65C??
Could that be in the form of a lower COP?

As I understand heat pumps, they are at their most efficient when raising large quantities of water a few degrees, and the efficiency drops off the higher you raise water temperature. Which is why ASHPs are so suited to swimming pool heating where thousands of gallons are raised a few degrees.

The trouble with all manufacturer's brochures is that it is difficult to get an overall COP for their systems.

I really would like to see some more performance data from the manufacturer.

albyota

From Microgeneration Certification Scheme Website

Air Source Heat Pump

Air source heat pumps (ASHP) absorb heat from the outside to heat buildings. It is even possible for air source heat pumps to extract useful heat from air at temperatures as low as minus 15°C.

For every unit of electricity used to power the pump, 3-4 units of heat are produced, making it an efficient way of heating a building.

How much will you save?
Fuel Displaced £ Saving per year CO2 saving per year
Gas £300 830 kg
Electricity £870 6 tonnes
Oil £580 1.3 tonnes
Solid £280 5 tonnes


How does it work?


In the same way that a fridge uses refrigerant to extract heat from the inside, keeping your food cool, an air source heat pump extracts heat from the outside air, and uses it to heat your home and hot water. An air-source heat pump has three main parts:

• The evaporator coil absorbs heat from the outside air;
• The compressor pumps the refrigerant through the heat pump and compresses the gaseous refrigerant to the temperature needed for the heat distribution circuit;
• The heat exchanger transfers the heat from the refrigerant to air or water.

In an air-to-water system the heat produced is used to heat water, which can be used to pre-heat water in a storage tank or circulate through underfloor heating or radiators. Heat pumps produce hot water that is a lower temperature (typically 35-45°C) than standard boiler systems, which makes underfloor heating the most effective option. In an air-to-air system this heat is used to produce warm air, which is circulated by fans to heat a building.

What options are available?

There are two types of air-source heating systems. Air-to-air systems provide warm air, which is circulated to heat the building. Air-to-water systems heat water to provide heating to a building through radiators or an underfloor system.

How much does it cost?

A typical 5kW domestic system, suitable for a well insulated detached property, costs in the range of £6,000 to £8,000 installed (ex VAT).

Is it suitable for my home?


What to keep in mind when considering an air source heat pump.

• You will need space on an external wall outside your house to fit the evaporator coil.
• An air source heat pump should cover the heating requirements of a well insulated property. Due to the lower temperature compared with traditional boilers, it is essential that your home is insulated and draught proofed. These measures will lower your heat demand and make the system more effective.
• Consider what fuel is being replaced: if it's electricity, oil, Liquid Petroleum Gas (LPG) or coal, the payback will be more favourable than gas. Heat pumps are a good option where gas is unavailable.
• The type of heat distribution system. Air source heat pumps can be used to heat water that is circulated through radiators but under floor heating is more effective due to the lower temperature of the air/water produced. Air-to-air systems require a ventilation system with fans to circulate the warm air.
• Is the system for a new building development? Combining the installation with other building works can reduce costs.
• If you want to further reduce your home's CO2 emissions you can purchase a green electricity tariff or install solar PV or some other form of renewable electricity generating system to power the compressor and pump.

dekh

albyota wrote: »

For every unit of electricity used to power the pump, 3-4 units of heat are produced, making it an efficient way of heating a building.

I think that's optimistic during winter when the system is most heavily used.

albyota wrote: »

How much will you save?
Fuel Displaced £ Saving per year CO2 saving per year
Gas £300 830 kg
Electricity £870 6 tonnes
Oil £580 1.3 tonnes
Solid £280 5 tonnes

This is much higher savings than the government figures which put gas at a saving of £50 pa. and no saving on CO2. This is a money saving forum not the green money saving forum.

albyota wrote: »

A typical 5kW domestic system, suitable for a well insulated detached property, costs in the range of £6,000 to £8,000 installed (ex VAT).

In real terms... £6900 to 9200 just puttting ex VAT doesn't mean you don't have to pay it.


So absolute best case for their figures is electric replacement:

£6900 / £870pa = 7.9 YEARS

Figures do not include interest on the £6900 if taken as a loan or loss of interest if the money had been invested instead and does not include energy price rises (which would help with break even).

Another rip off system. 1 year parts and labour warranty or 10?

Cardew

dekh

Firstly VAT is 5% on Central Heating intallation(not 17.5% or 15%)

You rightly make the point that in fitting any form of improvement to your property - e.g. Any type of Cental heating, insulation, solar, etc etc - it is a valid argument to consider the return on investment.

Not only do you have to consider capital installation costs, but loss of interest on that money(or cost of borrowing) maintenance, and future replacement of the CH system.

Central to that argument is the annual saving in running costs you might make.

The generally accepted year round COP figure for an ASHP system is around 3.

A small flat, with people at work all day might spend say £600pa on all electric heating. So with an ASHP savings might be in the order of £400.

A larger property with people home all day might spend £2000 and thus could save £1300 a year.

dekh

VAT at 5%

£6300 / £870pa = 7.24 years

The lower rate of VAT "doesn't apply if you're having them installed as part of a larger project such as a new roof or building an extension." - hmrc.gov.uk

So be aware.

And yes, you need to do the calculation as related to your own circumstances. I'm only going off the figures supplied.

Do any of the companies selling the systems guarantee the savings?
Still haven't had a word on warranties either.

6300 / £400 = 15.75 years
6300 / £1300 = 4.8 years

ROI is far too long as a replacement for an existing system.

Cardew

dekh wrote: »

VAT at 5%

£6300 / £870pa = 7.24 years

The lower rate of VAT "doesn't apply if you're having them installed as part of a larger project such as a new roof or building an extension." - hmrc.gov.uk

So be aware.

And yes, you need to do the calculation as related to your own circumstances. I'm only going off the figures supplied.

Do any of the companies selling the systems guarantee the savings?
Still haven't had a word on warranties either.

6300 / £400 = 15.75 years
6300 / £1300 = 4.8 years

ROI is far too long as a replacement for an existing system.

In fact the ROI is far longer than you quote.

£6300 invested at 4%(after tax) compounded produces £250 initially.

I think that ASHP systems have warranties from 1 to 3 years.

The Ecodan for example is 3 years if installed by an approved supplier. It also needs an annual check by that supplier - I suspect that the warranty is invalid unless you fork out for the inspection.

Your valid argument on ROI applies of course to any form of CH installation.

IMO it would be unwise to even consider an ASHP if you had gas or even oil at current prices as the savings do not justify the capital expenditure.

samtheman1k

I don't think you can really compare the CO2 benefits of an ASHP, as it is completely dependent on how you generate the electricity! If you only use renewable electricity, e.g. wind farms, then sure, you'll save CO2 compared to gas/oil, but not compared to a straight electric system, as that will also be zero (excluding wind farm building costs etc of course ). If your electricity comes from an old style dirty coal station, then, even with a COP of 3, you may still generate more CO2 than gas. IIRC, most electricity in the UK is generated from gas anyway, so there's a challenge to see if you save CO2!!!