Heat pump / inverter DIY

stevehead

paceinternet wrote: »

stevehead, do you have any more details or links to the actual standards?

Yeah, got a good one here

This document explains what JIS - C9612 is all about. Test conditions are explained.
JIS = Japanese Industrial Standard
C9612 is identical to ISO 5151-94, the one you'll find for non ducted aircon at https://www.iso.org

paceinternet wrote: »

Still very good, but not 5.45 continuously in all conditions.
If you understand this to be different, please let us know.

I do understand that it is defying physics for the COP to remain constant as the load increases, same as I don't expect my car to always do 56mpg. A sebuk type rating would be better as the COP value would be UK seasonally adjusted. Mind you sebuck band A has a range of 10% so it's not that accurate anyway.

mech_2

We need proper seasonal energy consumption data rather than instantaneous figures. This would implicitly include the defrost cycle, cycling losses, off-cycle consumption by the electronics and any tail-off caused by frost build-up prior to a defrost.

Then figures for the same building (with the same insulation levels) with a SEDBUK A rated boiler (with electrical usage of the boiler added in too).

Hot water figures would be useful too for comparison with a combi.

Until then it's just a lot of hot air (excuse the pun, couldn't resist).

Electric air source heat pumps are certainly the way to go for electric-only properties, but I'm not yet convinced it can compete with a modern gas boiler. Yes the technology may improve, but so may gas-fired technologies.

Cardew

stevehead wrote: »

Cardew please.... broaden your mind a bit here. I don't understand why you can't accept a performance above some arbitary value you've drawn in your own head.
Mitsubishi DO specify a COP of 5.45 for their system. They claim it right here in the Technical Manual for the product all in their own words. Look on page 2... under Specifications. It says right there in Black & White it delivers a COP of 5.45 in Heating. This is achieved at an outdoor temp of 6/7C and an Indoor temp of 20C. The standard is called ISO-T1, JIS C9612.
This is where you put on your best Victor Meldrew voice and exclaim "I simply don't believe it!"



I'm actually a bit stunned that when I post genuine energy usage stats for these systems it gets written off as 'Pure Fantasy'. I think the very best thing I can do in these Forums is present ashp as a very very good thing and back it up as best as I can with kwh usage stats and environmental conditions. A COP of 3 is acceptable, same as a cat Gas Fire. A COP of 5 just out there in a class of it's own - unbeatably cheap heating costs by a big margin.

You tell me then Cardew, is there anything I can do.... any measurement regime or method... whatever you like.... that could demonstrate to you that the huge moneysaving / carbonsaving potentials I have claimed for my ashp are true?
Respectfully Yours

Yes there is something you can do!

Get Mitsubishi to write what COP they expect a ASHP system to achieve in a typical UK winter. You know what I mean by system? - all units fans, defrost cycle etc etc incl low temperatures.

The technical director of Mitsubishi talks about his latest systems having a COP of 3.

The internet is full of forums where people say they are getting a COP overall of 2 or so(and are pretty happy with that)

The latest Energy Saving Trust and several other independant sources(up to date) talk of a a COP of up to 3 for a system.

To quote the theoretical COP at 7C and 20C is meaningless in real life.(and Mitsubishi to their credit don't use that). It is like my car on an indoor rolling road at a steady 30mph giving 60mpg and I quoting that as my car does 60mpg.

And yes! your figures in the other thread were absolute fantasy.

You claimed that for £30 a month you were producing heat that cost you £120 a month with Gas CH. Gas mind you!!!

I did some investigation in the USA on Heat Pumps - where I have my system.

It was a very easy project as there are some brilliant US Government websites - see:

http://apps1.eere.energy.gov/consumer/your_home/space_heating_cooling/index.cfm/mytopic=12620

Actually the best figure I have ever seen was an overall COP of 4 for a Deep Bore GSHP.

I really don't want to get into an argument with you or any other contributor to this forum because, as said previously, I am a fan of heat pumps.

I would add that I am a Director of an organisation in the USA and I wrote a report(I am a Chartered Electrical Engineer) which resulted in us fitting a very expensivie Heat pump system to a large swimming pool.

However, you really cannot pluck a COP figure from a tech spec and quote it out of context. Your contributions here lead people to believe that they are going to get 5 units of heat for 1 unit of electricity all winter - and they aint.

P.S.
I did read somewhere that a boffin had calculated the theoretical highest COP is 11(eleven) but he was talking about getting down to absolute Zero Kelvin to extract the heat.

richardc1983

Point is though Mech, in the near future gas supplies are going to run out, people should be looking for heat pumps to install really as the more properties that have boilers fitted the gas is going to run out.

richardc1983

Cardew I must admit the equipment I got is not Mitsubishi, its LG (a lot cheaper) and I think it has a cop of about 2 although with it being a pick and mix system, (you pick the combination of indoor to outdoor units) so they dont test every system combination but there is a cop of either 2 or 3 at the 20C indoors 7C outdoors. I am not going to do a big test as I am happy that I am saving money as normally when my central heating goes off (landlord is tight) so we have no control over it we would usually have to get electric heaters out. I leave units on 24/7 if im in and the house is always warm and im using about £4/£5 a day based on 17.85p per unit of electric (coin meter ripoff job). Previously when we plugged in electric heaters to heat one room (the lounge) we would be feeding in upto £12 a day and struggle to heat the lounge so I am happy with the progress I have made. But if I got my own house I would prob have higher range equip installed over central heating as I prefer the way the heat is distributed, prefer warm air heating.

I have an energy meter for my meter but cant measure the individual cost of the system as it is Hard wired into the house and not a plug so I have to take into allowance my other electric usage as well which guaranteed at night is not much as everything including set top boxes etc is swithced off at the wall.

mech_2

richardc1983 wrote: »

Point is though Mech, in the near future gas supplies are going to run out, people should be looking for heat pumps to install really as the more properties that have boilers fitted the gas is going to run out.

Too late. Most of us already have boilers fitted. But if we can halve the average household gas consumption over the next decade or two, that will have a big impact on demand.

There's no immediate panic. There's enough gas available to Europe for at least the probable lifetime of heating systems installed now and probably for the heating systems that will replace those too.

On the basis that electricity is generally produced from fossil fuels, switching to electricity doesn't seem like a solution to me. Unless you think the UK's heating requirements can be entirely powered with windmills and photovoltaics in the next 15-20 years, electricity isn't a better option than a similarly efficient use of gas (except that with electricity you have to fund the building of power stations too).

richardc1983

Heating appliances that use electricity that also use it efficiently may help though do you not agree.

rothers8080

I'm all for nuclear power myself, it irritates me how far ahead France are in that respect.

stevehead

There is no way of measuring the COP of a system - not for the end user anyway. All you can measure is the amount of energy used to keep yourself comfortable and everything else is a variable.

I thought I would be able to get accurate usage statistics on how much electricity my ASHP was using by plugging each unit into the mains via a Maplin Energy Monitor. These obviously don't work properly as the KWh result they gave me at the end of 1 month are aa Complete Fantasy.... much lower than it 'should' be.
I'm just off to phone the electricity board to get my meter checked - it's going round much too slowly and it must be busted!

stevehead

craigix wrote: »

I'm all for nuclear power myself, it irritates me how far ahead France are in that respect.

It irritates me too; James May would have us believe we're still a nation of engineers and we could be knocking up nuclear generators in our garden sheds. We don't have the skills to do this on a grand scale and will have to buy in the technology from the French - who are busy building nuclear power plants for other countries when they have the time or inclination.

Perhaps Mr. G . Brown ought to consider throwing some of his economic stimulus package millions at the UK ASHP industry so we can become world leaders in the field.