Heat pump / inverter DIY

richardc1983

4.6kw is the rating, what you wll get out of it. The cop is basically a calculation of the energy the unit uses to achieve the 4.6kw. THe final number is your cop value.

paceinternet

Please acknowledge my post #65, or show me some evidence that a COP of 3 is available in all conditions. It isn't. The "Aircon" industry seems to use a value which has some "seasonal" calculation built in so that all equipment can be compared.
There is much more data available from the air to water heat pump brigade who seem prepared to tell more of the story, but they do not have to comply with the "Aircon regs" whatever they are.
In both cases, it is still a good story, but if you are checking your electrical consumption during a week of -5 degC outside, it is unlikely to be the same as when it is +10 degC outside.

For some definitions:
http://www.comfort.uk.com/faq.htm#cop

For a graph that might typically apply, see the eficiency section:
http://www.fosterair.com/heatpumps_and_air.html

Cardew

paceinternet wrote: »

Please acknowledge my post #65, or show me some evidence that a COP of 3 is available in all conditions. It isn't. Mitsubishi and many other "Aircon" specialists just don't explain fully. There is much more data available from the air to water heat pump brigade who seem prepared to tell the whole story. It is still a good story, but:-

For some definitions:
http://www.comfort.uk.com/faq.htm#cop

For a graph that might typically apply, see the eficiency section:
http://www.fosterair.com/heatpumps_and_air.html

It would be interesting if manufacturers published some accurate graphs plotting COP against ambient air temp.

This was on that was published in an earlier thread:

Here is the input/output power of the Triance Activair heat pump, which was my 2nd choice (decided against due to the minimum operating temperature of -5degC compared with the Mitsubishi's of -20degC). This is the 12kW version I think which is probably what you would want for a 3/4 bed house.

The figure in brackets is the input power.

So at 5C the COP is just over 3.

stevehead

anthonykeates wrote: »

I got a question (probably a stupid one!).

If a unit's specs say it's got 4.6kW of heating capacity (for example the link below) is that the maximum it can achieve? Or will it achieve the 4.6kW times the COP (which will vary with outside temp), say 3 times 4.6 = 13.8kW? Or will it always have a capacity of 4.6kW, just that the higher the COP achieved the less electric used to get the rated heating capacity? Hope that makes sense!

http://www.orionairsales.co.uk/mitsubishi-heavy-industrial-srk20zgx-s-28-kw--9000-btu-hyper-inverter-air-conditioning-220-p.asp

Those are my units Anthony; and 4.6Kw is it max rated comtinous output. But like electric motors, they can be run at over their cont rated performance for a short time. These units have a 'Turbo' Mode which bumps it up by about another 1/3rd for 15 mins. It pulls 1350 watts or more in Turbo, and is a really powerful heater.

According to Mitsubishi spec sheet, the Heat output ranges from 0.5kw - 4.6kw.
According to my meter, the input ranges between 330w - 950w of power. It's variable.

I've never seen a COP performance curve for this unit. however, the spec sheet states the COP value of 5.45 at ambient temp of 6 degrees. This is well matched to the UK climate, certainly down south here in Devon.

stevehead

For both air & ground source heat pumps, you can check the Carbon Trust Energy Technology's List. The list shows systems that have gained ECA Accreditation.
This provides an endorsment that should help prospective buyers choose an energy efficient system.

mikedain

richardc1983 wrote: »

4.6kw is the rating, what you wll get out of it. The cop is basically a calculation of the energy the unit uses to achieve the 4.6kw. THe final number is your cop value.

Hi Richard

So for my unit (http://www.mgr-ac.co.uk/productView.asp?productID=5&categoryID=2) which has a COP of 2.76 and is rated at 1450 watts, does that mean it pulls a max of 525 watts?

Cardew

mikedain wrote: »

Hi Richard

So for my unit (http://www.mgr-ac.co.uk/productView.asp?productID=5&categoryID=2) which has a COP of 2.76 and is rated at 1450 watts, does that mean it pulls a max of 525 watts?

1450 watts is the input power on heating.

So with a COP of 2.76 it produces 4kW

Johnhowell

My post at: http://forums.moneysavingexpert.com/showthread.html?t=1328643&highlight=Heat+pump+%2F+inverter has run for a couple of weeks now.

What I would like to know is how to determine which Wattage/BTU unit is required for a conservatory south facing - area approx 25sq m and volume approx 65 cu m.

I initial looked at: LG Air Conditioning S09AW-N40 Wall Mounted Heat Pump 2.6 Kw / 9000 Btu Inverter:

[FONT=Verdana, Arial, sans-serif]http://www.orionairsales.co.uk/lg-ai...rter-585-p.asp [/FONT]

but possibly need a larger 18000BTU unit?

What is the calculation?

Also, has anyone else got the 5% VAT rather than the 15% VAT?

Many thanks,
John

richardc1983

I only paid 5% vat, its a good saving.

Mikedain sorry for late reply but its stopped notifying me of new posts for some reason although am subscribed.

Cardew is correct in what he says.

anthonykeates

5% VAT rate only applies to such products as air source heat pumps when you pay for installation (the rate then applies to the cost of the equipment plus the labour/installation). There also appear to be grants available under this government scheme - http://www.lowcarbonbuildings.org.uk/how/householders/ of 30% of the cost (max £900) providing you've first undertaken 'energy-saving steps'.

Anyone got any experience of the latter - certainly worth a go by the sounds of if!