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dipper
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  #2347150 1-Nov-2019 12:32
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Yes its the 390w compressor.

 

It runs after each major use i.e. having a shower and if we all have showers it can run for close to three hours.

 

We live in Christchurch so it gets cold over winter. Here is the installed system

 

Click to see full size

 

I note that Lion installed the system in a brewery that they opened here in Christchurch

 

 

 

 




gchiu
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  #2347152 1-Nov-2019 12:43
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I saw the news about the Lion Brewery installation.

 

Yours looks like it's also hooked up to hydronic heating.  How big is your concrete slab and is it just the one unit that does slab and HWC heating?


dipper
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  #2347153 1-Nov-2019 12:47
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No its actually hooked up to a water manifold to help balance the distribution of water over the house i.e. we can have two showers running at once with next to no change in water pressure and no change in temperature 




gchiu
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  #2347794 3-Nov-2019 13:25
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So, the cost of the system and potential pay back period seems reasonable.  I wonder why more people aren't doing this?

 

It's essentially refrigeration technology which is well understood.  So, it does seem a bit expensive for the technology, and presumably you could halve the cost by sourcing the components from overseas yourself...


gchiu
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  #2350760 9-Nov-2019 15:55
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Looks like my question has been answered.  One company is putting the panel in the ceiling cavity but there's now the extra cost of a fan to pull the hot air across the collector.

 

https://www.heatco.co.nz/products-info/2018/11/23/green-e-pack

 

Of course how do you get the panel into the ceiling cavity if it's a retrofit?


gchiu
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  #2352761 13-Nov-2019 13:42
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Some more interesting data

 

 

 

http://www.buildmagazine.org.nz/assets/PDF/Build120-56-Water-Heating-Options.pdf?

 

 

 

says that an average electric HWC has a COP of 0.7 which if highly insulated can go up to 0.9.  11 heat pump HWC were surveyed by BRANZ and found COPs up to 2 could be achieved.  A COP of 3 was easily achieved using a solar hot water system (presumably evacuated tube or flat plate).

 

One would think a solar assisted heat pump like the thermodynamic panels should be above 2 but they seem to have a problem demonstrating that.


 
 
 

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MartinGZ
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  #2352843 13-Nov-2019 16:52
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gchiu:

 

One would think a solar assisted heat pump like the thermodynamic panels should be above 2 but they seem to have a problem demonstrating that.

 

 

Exactly! Over a year ago I asked Geoff Read of The Alternative Energy Company to provide data that the system is viable in NZ. We are still waiting. My advice is if companies cannot prove their systems, move on. There is plenty of stuff out there that does work.

 

@gchiu stated a while ago that there are some more case studies available. In the first instance, there is a world of difference between a case study and proven testing. I looked at the Nelson one which I had seen before. Something I note:

 

“Being a new house, they’re unable to compare before and after electricity costs, but Fraser has tracked their energy usage over two years and compared it with their last house. He believes strongly that they’re about $100 per month better off, thanks to their Energie Eco system.”

 

I’m sorry, but this is really, really bad. This is the owner guesstimating one house with a different house. You cannot compare two completely different houses with completely different systems – well, not without a lot of monitoring gear. Besides, anyone that can “save” $100 on water heating is using an awful lot of electricity and could easily save a truck load moving to a better house. As a comparison, my total average monthly electricity bill is $120. OK, log burner for the winter, but full home office with heat pump computers and laser printer, electric cooking, and winter hot water top-up on the solar hot water panels. Oh, and electric lights 😀





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gchiu
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  #2352861 13-Nov-2019 18:09
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The technology is almost the same as used in heat pumps for water heating.  Yet you can purchase a heat pump HWC for about $4.5 - $7.8k.  So, it's unclear to me as to why the thermodynamic panel systems are so much more expensive.

 

One thought occurred to me is that you could greatly improve the efficiency of these things by building a solar air heater yourself, and pumping the hot air produced over the thermodynamic panel.  The fan power can be provided by a very small PV panel.


SomeoneSomewhere
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  #2354545 16-Nov-2019 01:18
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gchiu:

 

The technology is almost the same as used in heat pumps for water heating.  Yet you can purchase a heat pump HWC for about $4.5 - $7.8k.  So, it's unclear to me as to why the thermodynamic panel systems are so much more expensive.

 

One thought occurred to me is that you could greatly improve the efficiency of these things by building a solar air heater yourself, and pumping the hot air produced over the thermodynamic panel.  The fan power can be provided by a very small PV panel.

 

 

A standard hot water heat pump is an integrated unit, built and commissioned in a factory.

 

 

 

One of these is a split system, so you have to run & purge refrigerant linesets, plus you have to deal with roof access.

 

 

 

Even $5k sounds kind of high for a HWHP - you can get a couple-of-kW split AC unit installed for ~$3k.


gchiu
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  #2354572 16-Nov-2019 10:42
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https://www.hotwatercylinders.nz/heat-pumps/heat-pump-hot-water-cylinders.html

 

 

 

That seems to be the ball park figures for heat pump hot water cylinders.

 

BTW, those panels don't have to go onto the roof, they can be wall mounted preferably facing north.


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