Air Source Heat Pumps

tpresto3

paceinternet wrote: »

tpresto3, can you review what you are saying in post #316
Oil - "the actual cost is around 5p per kWh."
Gas - "and thus you actual cost per kWh of gas is 5p."
Heat pump - "then in reality, currently you are saving 5p per unit compared to gas or oil."

Also rather confusing when you say "will not save as much money as a unit such as the Danfoss AX unit, which boasts up to 1 unit in, and 4.6 units back out".
In your later posts I think you are alluding much more to reality, whereas the Danfoss numbers should be compared with others at the same air and water conditions. And those conditions should be realistic.

THANK YOU.

I agree that it does look confusing.

I tend to run away with myself when I am writing.

What I am trying to say is broadly speaking, you can expect to pay the following.

5p per kWh for conventional fuels (this will vary depending on the efficiency of your equipment and supply prices).

To obtain 3kW of heat energy from a heat conventional system, you would have to pay 15p.

Using a heat pump with an actual CoP of 3.1 you would need to use 1kWh of electricity, which may cost you around 10p.

Thus, for 3kWh of heat energy, you would spend 15p using conventional systems, or 10p using a heat pump.

Some heat pumps do offer higher CoP's. The new model I mentioned before offers a CoP in excess of 450%. This does include hot water, and will provide hot water at 60oC as whilst the air is 0oC or above.

Again, this heat pump as been tested to the same European specifications.

Thus, if you do obtain a CoP in excess of 400%, the savings are greater.

1 unit of electric will give you 4 units of heat energy, thus saving you more money. Obtaining 4 kWh of heat from gas or oil may cost you 20p, whilst using a good heat pump it would cost you 10p. Thus, in this scenario the savings a greater.

I hope I have managed to explain myself a little better this time.

Once again, many thanks

Cardew

tpresto3 wrote: »

THANK YOU.

I agree that it does look confusing.

I tend to run away with myself when I am writing.

What I am trying to say is broadly speaking, you can expect to pay the following.

5p per kWh for conventional fuels (this will vary depending on the efficiency of your equipment and supply prices).

To obtain 3kW of heat energy from a heat conventional system, you would have to pay 15p.

Using a heat pump with an actual CoP of 3.1 you would need to use 1kWh of electricity, which may cost you around 10p.

Thus, for 3kWh of heat energy, you would spend 15p using conventional systems, or 10p using a heat pump.

Some heat pumps do offer higher CoP's. The new model I mentioned before offers a CoP in excess of 450%. This does include hot water, and will provide hot water at 60oC as whilst the air is 0oC or above.

Again, this heat pump as been tested to the same European specifications.

Thus, if you do obtain a CoP in excess of 400%, the savings are greater.

1 unit of electric will give you 4 units of heat energy, thus saving you more money. Obtaining 4 kWh of heat from gas or oil may cost you 20p, whilst using a good heat pump it would cost you 10p. Thus, in this scenario the savings a greater.

I hope I have managed to explain myself a little better this time.

Once again, many thanks

You are still posting confusing information IMO.

There is little point in talking about providing hot water at 60C with ambient temperature at 0C, then quoting a COP in excess of 450%, and later a COP of 400%.

Perhaps you can look up the specification for your system and state what the COP will be when producing water at 60C when the ambient temp is 0C.

If fact in an earlier post you(correctly) say that producing water for radiators at 50C wil 'kill your COP'. Yet you mention 60C and COP of 4.5 in the same paragraph.

A good overall COP for a top system(taking into account defrost cycles etc) will be around 3.0.(I can't think why you say 'forget COP' it is the overall measure of a system) and the generally accepted view(Energy Saving Trust etc) is that running costs for a heat pump system are about the same as gas.

Abacus

Hello, first time on this excellant site.

I have just got planning permission for a ground floor extension to my property. I currently have Economy 7 storage heating system (heat & water) with a large water storage tank. I also have a woodburning stove which we use occasionally in the winter when the heating needs a boost, predominantly in the evenings.

I am considering putting in a new heating system as part of the extension as if there's going to be a mess for 3 months then a little more to put in a new system will not make much of a difference. We have no gas supply to where we live, only electric.

As far as I can make out my options are:

1) Install Oil tank and oil wet heating system
2) Install Air source wet heating system
3) Upgrade storage heaters throughout

I have also considered solar panels but think the cost is still very high for these even though, bar winning the lottery, we do intend staying here for at least the next 10 years if not more.

My initial thoughts are that oil is currently quite pricey (I understand this could change) and that oil isn't a particularly 'clean' fuel so I am leaning towards option 2 or 3 at this moment in time.

I would appreciate any recommendations?

Cardew

Abacus wrote: »

Hello, first time on this excellant site.

I have just got planning permission for a ground floor extension to my property. I currently have Economy 7 storage heating system (heat & water) with a large water storage tank. I also have a woodburning stove which we use occasionally in the winter when the heating needs a boost, predominantly in the evenings.

I am considering putting in a new heating system as part of the extension as if there's going to be a mess for 3 months then a little more to put in a new system will not make much of a difference. We have no gas supply to where we live, only electric.

As far as I can make out my options are:

1) Install Oil tank and oil wet heating system
2) Install Air source wet heating system
3) Upgrade storage heaters throughout

I have also considered solar panels but think the cost is still very high for these even though, bar winning the lottery, we do intend staying here for at least the next 10 years if not more.

My initial thoughts are that oil is currently quite pricey (I understand this could change) and that oil isn't a particularly 'clean' fuel so I am leaning towards option 2 or 3 at this moment in time.

I would appreciate any recommendations?

Welcome to the forum.

Oil is not expensive to run at current prices, it is comparable to gas. A litre of oil is around 35p and 'contains' 10.2kWh. However prices have been volatile in the last couple of years.

It is also expensive to install and you need spsce for a tank.

Another option, depending on the size of your extension, is a simple ASHP with a fan - cheap to install and run - and keep your current CH.

Solar cannot provide CH.

Hermann

Always difficult to comment without knowing all the details/location/budget.

However, generally speaking if budget allowed Id be thinking .....

Insulate! very well and draughtproof too!

Keep Woodburning stove (assuming it has a boiler to heat the water, if not perhaps consider adding flue heat recovery to heat water)

Install Solar Thermal (eg Evacuated Tubes)

Install Heat Pump

Depending on house Install underfloor heating or oversize rads.

Possibly consider a Thermal Store (as you're likely to have excess heat at times from solar thermal and also Woodburner.)

That way when the sun shines you get free heat (mainly DHW although with a thermal store you may get some contribution to Space heating).
When the sun is not shining you can choose between lighting the WBS or using the heatpump.

If it gets too cold for the heatpump light the WBS.

Only trouble is ......

a) This will cost a lot to install.
b) It can be difficult to find an installer capable/experienced of interlinking the three systems.

On the plus side ....

You can get some grants in some areas.
You can also get paid for the thermal Kw your solar produces. (schemes such as GoodEnergys)
In future you may get paid for the thermal Kw your Heatpump (and perhaps WBS as a biomass??) produces via RHI payments.
As has already been said in this thread to recieve future RHI your likely to need an accredited installer which will add a fair bit the cost.

albyota

Welcome Abacus, For what its worth,
I have warm water underfloor heating (and personally would not go back to radiators), this is fed by an ASHP it also supplies all our hot water needs for a family of 5, there is no need for electric boost. (Can supply running costs if required).
If your extension permits, consider UFH along with radiators for the rest of the house.
Don’t be put off by the (OVERSIZE radiators bit) A 600mm x 1000mm radiator can be single panel, P1, single with convector P+, double panel with single convector K1, and a double panel double convector K2…. It’s the same physical size…just a bit thicker but will give out 3 times as much heat as a single panel radiator.

An air to water, air source heat pump, supplying your hot water requirements along with correctly sized radiators and UFH is, IMO going to give you a quicker payback with reduced annual running costs, with the potential, (when green electricity is more widely available and dare I say it cheaper than fossil fuels).
ASHP’s are generally maintenance free, so no annual service charge. Have 3 or 5 yr guarantee, will probably outlast today’s new (Fossil Fuel) boilers, some would disagree though. Worth considering government’s C02 climate levy tax.

Storage heaters are very cheap to install, maintenance free, fairly cheap to run (E7) but difficult to control (unless wired through contactor and weather compensation controller).

Oil boiler still quite cheap to run, quite reliable, annual service cost, volatile, globally political commodity, fluctuating price, less if bought in bulk, if you can store, bigger tank.

Do not bother with solar thermal panels or tubes, I have these too and have calculated that for 50p worth of 'free' hot water on the sunny days (in the UK?) then average cost of installation for 4 square meters is £2400, that’s 4800 days (of 50p’s worth).....13 years payback....spend money on something else.

You will have to satisfy Building Control Officer for building regs anyway so pay particular attention to the insulation, spend your money here along with good double glazing.
BCO may even insist on installing Mechanical Heat Recovery Ventilation for part F. (ventilation air tightness). Part L1B & L1A conservation of fuel & power in new & existing buildings.

Lots of decent folk on this site with our own opinions / advice, however, you have the ultimate decision. Good luck with it all

samtheman1k

tpresto3 wrote: »

2. Different heat pumps offer different efficiencies. Thus, a system that gives you an efficiency of 1 unit in and 3 units out ( a common scenario with most heat pumps ) will not save as much money as a unit such as the Danfoss AX unit, which boasts up to 1 unit in, and 4.6 units back out. To my knowledge, this is the highest on the market, and includes domestic hot water (unlike many of the cheaper units on the market)

That conveniently placed word 'up' sums up all the misleading advertising perfectly!!!:T

samtheman1k

tpresto3 wrote: »

I would estimate that over the next 3 years, energy prices will double.

Can you explain how you came to that conclusion?

Cardew

would estimate that over the next 3 years, energy prices will double.

samtheman1k wrote: »

Can you explain how you came to that conclusion?

It seems to be is a standard ploy for salemen to think of a figure for fuel price inflation, quadruple it and then add some extra.

I get heartily sick of salesmen coming on MSE to peddle their wares with misleading and exagerated claims.

The pity is that Heat pumps(unlike solar) are an excellent product and the salesman's rubbish posted above causes damage.

stevehead

It's not an unreasonable assumption chaps
http://www.wtrg.com/oil_graphs/oilprice1947.gif
it quadrupled 00 - 07
I guess it's the motive behind the statement that's in question.