[Greenbuilding] Nyle heat pump water heater update

[kaze0010 at umn.edu]

On May 23 2013, Reuben Deumling wrote:

>On Thu, May 23, 2013 at 6:25 PM, Nick Pyner <npyner at tig.com.au> wrote:
>
>>
>> Resistance heater 4.9
>> heat exchanger     2.1
>>
>
>Oh, I thought those thingies worked without external input of energy. Must
>be Carmine's device that does that.
>
>>
   I submit you will never know how well anything works unless you compare 
it
>> to the usage.
>>
>
>But I'm less interested in the device all by itself; I'm interested in the
>real world performance with all the particulars. If someone manages to get
>by on 1/14th of a gallon of propane/day to heat his water in a sidearm
>water heater I want to know about it. I care far less that the 8 gallons of
>hot water he uses isn't normed. Besides if we know both the water and
>energy usage the differences in use rates can be zeroed out.
>
   An electric resistance heater has such a low installed cost it can be 
made
>> to beat a solar system any time. All one has to do is shower once a week.
   An electric resistance heater is an anethema to me but, right now, I am 
in
   the process of installing a new one. One of the reasons for this is that 
I
>> could well be dead before a solar system is amortised.
>>
>
>It seems you are ranking these according to first cost or at least a money
>scale. I would think a different (energy) scale might be more appropriate.

The concepts Martin Holladay outlines in this article give an additional 
perspective on electrical resistance heating that is sure to raise some 
eyebrows. "It’s now cheaper to use a photovoltaic system to heat domestic 
hot water" (at least in some situations).
http://www.greenbuildingadvisor.com/blogs/dept/musings/solar-thermal-dead

I think a similar argument can be made regarding certain home insulation 
retrofits vs applying the same funds to an low temperature capable air 
source heat pump and more solar PV.

Low module prices, even for quality modules from Kyocera or SolarWorld, 
really make a difference in what makes sense. Probably the most ironic 
piece in the whole water heating thing is the disconnect in using a piece 
of high tech electronics (solar module) and an inverter to run a low tech 
resistance element. (The inverter might be cut out of the picture, but then 
you may run into the power control issues related to switching high voltage 
DC.)