ASHP or GSHP or Solar panel

albyota

Cardew, these 'VERY POOR' results seem to be getting Poorer and poorer and poorer and even more 'Disastrous', and 'Horrendous' with every one of your posts, please lets put it in to perspective, 29 heat pumps (ASHP's) were tested.......thats all.......29..!!!, over two years ago, the industry has moved on a lot since then, there are 1.2 million boiler replacements every year, with thousands of very poor, disastrous, horrendous, dangerous cowboy installations within the gas industry. There are many many threads on the gas and electricity pages of this forum with frightening stories of ill fitting systems, rip off merchants, undersized combi's in large houses.....boiler breakdowns etc
You have mains gas central heating.....AND.....you are on economy 7... is that moneysaving....?

What are your annual household bills.....?

As soon as someone comes to this forum to inform other readers (not just you) of how their system is performing, they are made to feel as if they have done wrong......

Please understand the villages that do not have mains gas have either LPG (rip-off tie-in contracts), direct electric (NSH) or heating oil (DCC Cartel), and the new regulations surrounding the type and location of oil tanks means that in a lot of cases, the cost of installing a heat pump is not that much different to replacing a boiler and a new repositioned Bunded oil tank and the running costs are lower...... I do, however share your point that it seems like it has been pot luck, if you get a good one or a bad one.....soon to be sorted...I hope, rant over...sorry:eek:

Edale

Cardew, I have to agree with you, too much of what I say is opinion even if it is reached with an element of logic and reason. I also agree with the 'pot luck' element of what you say and this is unacceptable to anyone spending this kind of money.
I am no 'ecomaniac' but believe heat pump technology can and should work, especially off mains gas but runs the risk of being destroyed by incomeptent suppliers who will jump on the bandwagon, you only have to look at the exhaust heat pump threads to realise this.

I appreciate your efforts to temper the illogical claims that are made, indeed Mitsubishi quote on their website that 'For every 1kW of electricity fed into Ecodan, you will get at least 3kW of heating energy.'

You are right in that the risk should be on the suppliers of these systems rather than on the consumers willing to pay double the price of a traditional system.

albyota

Edale wrote: »

claims that are made, indeed Mitsubishi quote on their website that 'For every 1kW of electricity fed into Ecodan, you will get at least 3kW of heating energy.

Generally the quoted COP is a seasonal average.......in the warmer months the COP can be as high as 4.5 - 5.0.....in the coldest weeks of winter minus 7, the COP can be as low as 1.2.

Cardew

albyota wrote: »

Cardew, these 'VERY POOR' results seem to be getting Poorer and poorer and poorer and even more 'Disastrous', and 'Horrendous' with every one of your posts, please lets put it in to perspective, 29 heat pumps (ASHP's) were tested.......thats all.......29..!!!, over two years ago, the industry has moved on a lot since then, there are 1.2 million boiler replacements every year, with thousands of very poor, disastrous, horrendous, dangerous cowboy installations within the gas industry. There are many many threads on the gas and electricity pages of this forum with frightening stories of ill fitting systems, rip off merchants, undersized combi's in large houses.....boiler breakdowns etc
You have mains gas central heating.....AND.....you are on economy 7... is that moneysaving....?

What are your annual household bills.....?

As soon as someone comes to this forum to inform other readers (not just you) of how their system is performing, they are made to feel as if they have done wrong......

Please understand the villages that do not have mais gas have either LPG (rip-off tie-in contracts), direct electric (NSH) or heating oil (DCC Cartel), and the new regulations surrounding the type and location of oil tanks means that in a lot of cases, the cost of installing a heat pump is not that much different to replacing a boiler and a new repositioned Bunded oil tank and the running costs are lower...... I do, however share your point that it seems like it has been pot luck, if you get a good one or a bad one.....soon to be sorted...I hope, rant over...sorry:eek:

Firstly I have Gas CH, but don't have Economy 7. You are possibly confused in that I have Economy 7 meters(they add the two readings)

I also use a huge amount of gas and electricity - but that is my choice of lifestyle.

The post above by Edale sums up my 'philosophy'!

I really can't suscribe to the argument that because there are poor gas/oil/lpg installations, we shouldn't 'pick' on Heat pumps. This thread is about the limitations of heat pumps.

There are too many people on MSE who are either heat pump enthusiasts, or are in the trade and have a vested interest in promoting the technology. You are in the latter category(or perhaps both;)) albeit your posts are well balanced.

I also don't get this 'only 29 ASHPs' in the trial argument. The trial is still ongoing so it is not yesterday's technology.

Surely the whole point is that trial is just about the only objective and quantifiable evidence I have seen and the results surely are poor? You cannot just dismiss such a trial.

We are however in agreement about the pot luck element!

albyota

Cardew, sorry for the rant, I do understand the need for the continued trials, and hope that the results are a whole lot better, and I hope that since MCS have been monitoring and auditing companies and the manufacturers are weeding out the cowboys, heat pumps will be the considered choice......especially in rural locations.....and only when the house it is being installed in, has had all the necessary insulation and D/G and radiators calculated properly.

grahamc2003

Albyota, thanks for your posts, appreciate them, well balanced from an owner which, you must admit, is rare!. I'm interested in how these perform in the harsh winter like last year. Did yours suffer from a pronounced low cop last winter? Any icing problems? I must say, these things are easy to avoid by just turning the system off when, say 0C, and use other heating (probably easier said than done in practice for many). I'd do that to avoid the internal heating some units have turning on).

On a technical point, do you know the low temperture of the refridgerant, or alternatively, the temp gain of it over the 'warming (or cooling in summer) fins' before compression in the outside unit? I ask because if it's much below zero at that point, then there's a danger of deposition of ice on the fins even at highish ambient temps, if you see what I mean. (My dehumidifier sometimers enters defrost mode (i.s. stops dehumidifying) at room temperatures below about 7 or 8C). I wonder if that is coincidence, or whether that's why the cop on a heat pump system is quoted at 7 degrees? (i.e. defrosting may occur below 7).

Anyhow, appreciate your thoughts on your system's performance this harsh winter.

Swipe

Graham, I've never seen defrosting above 3C on my heat pumps. Most defrosting occurs when it's snowing or in freezing fog.

albyota

grahamc2003 wrote: »

Albyota, thanks for your posts, appreciate them, well balanced from an owner which, you must admit, is rare!. I'm interested in how these perform in the harsh winter like last year. Did yours suffer from a pronounced low cop last winter? Any icing problems? I must say, these things are easy to avoid by just turning the system off when, say 0C, and use other heating (probably easier said than done in practice for many). I'd do that to avoid the internal heating some units have turning on).

On a technical point, do you know the low temperture of the refridgerant, or alternatively, the temp gain of it over the 'warming (or cooling in summer) fins' before compression in the outside unit? I ask because if it's much below zero at that point, then there's a danger of deposition of ice on the fins even at highish ambient temps, if you see what I mean. (My dehumidifier sometimers enters defrost mode (i.s. stops dehumidifying) at room temperatures below about 7 or 8C). I wonder if that is coincidence, or whether that's why the cop on a heat pump system is quoted at 7 degrees? (i.e. defrosting may occur below 7).

Anyhow, appreciate your thoughts on your system's performance this harsh winter.

grahamc2003, mine is the 8.5 kW Ecodan, it is running a 210L standard coil 'OSO' DHW cylinder to 55 degrees twice a day and UFH for both floors, so the heating water temp is set at 36 degrees, I have witnessed it going in to defrost cycle (4 mins) twice in the same hour, only a few times when it was unusual very high humidity at minus 6 back in November, generally the defrost cycles were about 90 minutes apart, and no loss of heating was experienced, (not noticed with the thermal mass of UFH), Rads would be more noticable, there is no form of back up, no electric element (apart from the one in the cylinder for thermal disinfection once a week).

The published COP of my heat pump is on a seasonal average, and at air ambient 1 degree humid, water temp at 35 degrees, the COP is 3.17, at air humid at 7 degrees W35 the COP is 4.18, so when it was minus 10 the COP was at 2.09, (incidentally the COP at minus 15 is 1.77) this of course is at 35 degrees water temp, adjust the water temp to between 45 and 55 degrees as you would have for radiators and the COP changes to 1.46 at minus 7 and at about 1.1 at minus 15. Also at minus 7 the performance of the 8.5 kW unit drops to 7.7 kW so as long as the heat loss calcs consider this drop when sizing a system, then the system works happily. by the way your dehumidifier probably operates on R134a gas,
The heat pump uses R410A boiling point of minus 48.5 degrees :eek:

albyota

couldn't help posting this from an elderly couple in a 3 bed detached, Oxfordshire, previously on oil, now using a 5kW system.

Dear Mr *****,

The main piece of information which I can give you on my ASHP
experience over the last year is our total electricity consumption.
We used 6042 KWH from the end of March 2010 - 2011. This includes
normal consumption for heating, lighting, cooking and washing
machines, which I estimate to be about 1200 KWH, based on the previous
year. Hence the ASHP consumption is the difference, i.e. 4842 KWH.
During the very cold periods in the winter we used no supplementary
heating, although the occasional extra jumper was called for. I guess
that we almost always had an indoor living-room temperature of at
least 19 deg,C during daytime and evening, and once the curtains were
drawn, a couple of degrees higher. We are well insulated, with wall
cavity insulation, 300 + mm of loft insulation, and A-rated UPVC
double glazing in most of the house.

There were a couple of matters of concern. Firstly, during very cold
periods, (outside temperatures of -5 to -10 deg. C) the heating
exchanger became iced up, and stayed so - not thawing completely on
defrosting mode. It was necessary to defrost using warm water (after
switching off) on several occasions. Secondly, the outdoor unit proved
to be a bit noisy when working at maximum output. The noise problem
has been improved by the anti-vibration pads fitted by your service
engineer, but I don't know how it will be under very cold winter
conditions. However it is a fairly minor problem.

Taken over all, we are very impressed and pleased with the ASHP system
installed by...................

I would be very willing to talk to Mr ******** on the telephone.

I am happy for you to make use of the information I
have given above.

Regards

**** *****

paceinternet

Is the above reference about an Ecodan which could have been running on the circa 4 minute defrost cycle?
If so, there have been other posts elsewhere about incomplete defrosting in certain weather conditions. Is it adjustable on the Ecodan, or something you live with?