Heat pump / inverter DIY

Cardew

richardc1983 wrote: »

@ cardew, fair enuf but a boiler might drop its output but it still switches off once the flow temp has been reached. Inverters can lower output even further to hold the room temp without having to cycle off, reduced wear and tear.

"Fair enuf" ??

Hardly the most gracious admission that you were completely wrong;) -

Trying to qualify your mistake doesn't help - when in a hole, stop digging etc - that is nothing to do with the point you were making.

Whilst I understand all your enthusiasm for ASHPs, I do wish your posts, and those of fellow posters on MSE were a little more balanced.

Without repeating earlier comments of my appreciation of the merits of ASHPs, everything posted now paints too rosy a picture.

The COP of 5 is almost accepted as a given. Well Mitsubishi in all their latest case studies talk of an overall COP of 3 as far as I can see. Yes I appreciate there is a theoretical COP of 5+ but they don't claim that for their systems. Read their latest 264 page brochures and look at their website. I can also not find any graph of COP plotted against ambient temperature.

The Energy Saving Trust, and several other up to date independent sources, all talk of figures around a COP of 3.

Also heat distribution is a problem - not everyone wants doors to bedrooms open to get heat etc. My system abroad was incorporated into the design and is ducted with 10 outlet grills.

I honestly think that you would be doing a service to MSE readers if you gave frank appraisals of the systems - warts and all! After all a COP of 3 is excellent!

rothers8080

I've just spent a while playing with it, the lights definitely represent the power use, it seems that heat only mode is much less accurate than auto mode, it does eventually ramp it down just not in a neat way like auto mode does as it has no control over the fan, it just turns the fan on or off as it ramps the power use up and down. It seems to be about 2 degrees too high when it decides the temp is what you want (at that point the unit turns off) compared with what the auto mode thinks.

Heat mode with auto fan control would be nice.

It's 2.3 meters up the wall as recommended in the manual, so it's really high up (actually the manual demands it's at a minimum of 2.3, might have some trouble there with some houses, can't see the reason it can't be lower).

I'm trying to find a better manual for it online, I've found who really makes them (a Chinese company) and I'm looking though their distributors websites in the USA and Aus. The UK distributor just seems to have done a google translation of maybe a European manual and it does not cover the remote control at all.

Fun times

richardc1983

@ Cardew, would you like a medal??? I was agreeing with you. I dont know the ins and outs of how a combi boiler works, and im sure not all the new ones have the latest features. THe last boiler I saw and it was in my parents house didnt have modulation control and just went 100% each time.

I dont think im digging a hole either. My point about reduced wear and tear is also another benefit.

You also have to realise that this is a money saving forum, if people can get good heat distribution from leaving their bedroom doors open to allow air to circulate and only have 2 units such as Stevehead, then this is also great. For instance I have 2 units in my flat, 1 in the lounge and 1 in the bedroom. If I leave the bedroom door open and the lounge door open the heat circulates into the hall, kitchen, bathroom and bedroom thats with just one unit switched on. When I go to bed I close my door (partly to stop my cat going on the prowl round the flat) but also for privacy and I wouldnt want my bedroom warm anyway. The unit in the bedroom is used on a morning at the same time as getting up so for me it works well. A ducted unit also involves a lot of adaptation to an already built building and as you say it was incorporated into the design of the building. Costs would be far to high for me to do this so I have individual units, its a lot cheaper and looks smarter than an ugly radiator on the wall taking up space behind the sofa which also blocks the heat from it!

richardc1983

craigix wrote: »

I've just spent a while playing with it, the lights definitely represent the power use, it seems that heat only mode is much less accurate than auto mode, it does eventually ramp it down just not in a neat way like auto mode does as it has no control over the fan, it just turns the fan on or off as it ramps the power use up and down. It seems to be about 2 degrees too high when it decides the temp is what you want (at that point the unit turns off) compared with what the auto mode thinks.

Heat mode with auto fan control would be nice.

It's 2.3 meters up the wall as recommended in the manual, so it's really high up (actually the manual demands it's at a minimum of 2.3, might have some trouble there with some houses, can't see the reason it can't be lower).

I'm trying to find a better manual for it online, I've found who really makes them (a Chinese company) and I'm looking though their distributors websites in the USA and Aus. The UK distributor just seems to have done a google translation of maybe a European manual and it does not cover the remote control at all.

Fun times

If the fan is off it means the unit has either gone over set point and the outdoor unit swithces off or the unit is in preheat mode or defrost.

SO ur saying when its on auto mode the fan never goes off just slows up or down and there is always warm air blowing from the unit even when reached set point.

Cardew

[quote=richardc1983;17308503
You also have to realise that this is a money saving forum, if people can get good heat distribution from leaving their bedroom doors open to allow air to circulate and only have 2 units such as Stevehead, then this is also great. For instance I have 2 units in my flat, 1 in the lounge and 1 in the bedroom. If I leave the bedroom door open and the lounge door open the heat circulates into the hall, kitchen, bathroom and bedroom thats with just one unit switched on. When I go to bed I close my door (partly to stop my cat going on the prowl round the flat) but also for privacy and I wouldnt want my bedroom warm anyway. The unit in the bedroom is used on a morning at the same time as getting up so for me it works well. A ducted unit also involves a lot of adaptation to an already built building and as you say it was incorporated into the design of the building. Costs would be far to high for me to do this so I have individual units, its a lot cheaper and looks smarter than an ugly radiator on the wall taking up space behind the sofa which also blocks the heat from it![/quote]

Richard,
With respect you are illustrating exactly the overall point I was making.

Radiators behind sofas do not block heat!

Ugly radiators? Surely they are a lot less ugly than a blo0dy great box stuck on a wall.

Heat distribution is a problem. You may be happy with doors open etc but others won't - it ain't an advantage, it is a disadvantage. A discrete heat source in each room is obviously the best solution.

Your solution is an understandable compromise but you paint it as if it has nothing but adavantages.

All I am suggesting is to get some balance.

richardc1983

I understand what ur saying about balance, but I know in most my friends houses and familys, that only the lounge door is closed to keep the heat in? I want the heat to get out, when I go out of friends lounges into the hallway its always much cooler than the lounge, I have got a steady temp all the way through the flat. Theres a box outside but its hidden away and cannot be seen unless u walk round the back. The units inside are smaller than the radiators! Everything has its disadvantages. but ASHP's are better for enivornment than GCH so this is surely is more important. I am getting a further unit installed in my flat mates bedroom as he likes to have his door closed. The cost of getting another unit installed and hooked upto the existing outdoor unit is less than having a radiator installed!

stevehead

Cardew wrote: »

The COP of 5 is almost accepted as a given. Well Mitsubishi in all their latest case studies talk of an overall COP of 3 as far as I can see. Yes I appreciate there is a theoretical COP of 5+ but they don't claim that for their systems. Read their latest 264 page brochures and look at their website. I can also not find any graph of COP plotted against ambient temperature.

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!"

Cardew wrote: »

I honestly think that you would be doing a service to MSE readers if you gave frank appraisals of the systems - warts and all! After all a COP of 3 is excellent!

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

richardc1983

Well said Steve, tell me you didnt just get out of bed to write that!?

paceinternet

stevehead, do you have any more details or links to the actual standards?
I just spent some time Googling for them and cannot find the actual specification for the standard.
www.iso.org does not match anything for ISO-T1

I too consider heat pumps systems are potentially excellent solutions. I commend your enthusiasm for your system, and the very useful facts you have recorded, but it is also right to make people aware of how the systems will operate in different temeprature conditions. They need to know what their running costs and room temperatures will be at different external temperatures, but the simple COP you quote is inadeqate and misleading.

Edit: Whilst I haven't seen the document before, on page 9 of the Technical manual there are factors for lower external temperatures and defrosting cycles.
Example at -5 deg C external air temperature there is a frosting adjustment coefficient of 0.91 and - 5 deg outdoor to 20 deg indoor has a capacity coefficient of about 75 %.
Example at -10 deg outside to 25 deg inside could be around 50%.
Still very good, but not 5.45 continuously in all conditions.
If you understand this to be different, please let us know.

rothers8080

I was reading over Christmas there is a new unit in Japan which is claiming a COP of 6.1, even if that was only in favorable conditions it's still going to be well over 3 in every day use.

I wonder what the theoretical maximum is for this technology?