[Greenbuilding] Commercial Water Heaters

[Paul Eldridge]

Thanks, Richard. I'm greatly impressed by what you've been able to 
achieve thus far. Congratulations ! I find myself on a somewhat similar 
mission; namely: 1) to reduce our home's energy use to the greatest 
extent possible (but without giving up our dryer); 2) to minimize 
concurrent demand; and 3) to shift as much of our discretionary 
consumption to off-peak hours.

Our 2,500 sq. ft., circa 1968 Cape Cod is now, for all intents and 
purposes, all-electric and we've cut our total household requirements to 
just over 9,000 kWh per annum (the previous owners in the year prior to 
our purchase consumed some 5,700 litres of heating oil and 14,500 kWh of 
electricity). Initially, I thought I'd "quit" once we dropped below 
12,000 kWh a year, then 10,000, but now I'm determined to break through 
the 9,000 mark.

As you may recall, we have two Sanyo high efficiency ductless heat pumps 
and they supply 100 per cent of our space heating needs. These units are 
plugged into power monitors (so too our electric water heater) and this 
information is recorded in a spreadsheet. During the heating season, I 
also log hourly outdoor temperatures so that I can see how temperature 
influences demand.

You can view a breakout of our 2011-2012 heating season at:

Oct – http://i362.photobucket.com/albums/oo69/HereinHalifax/2011-10.jpg
Nov – http://i362.photobucket.com/albums/oo69/HereinHalifax/2011-11.jpg
Dec – http://i362.photobucket.com/albums/oo69/HereinHalifax/2011-12.jpg
Jan – http://i362.photobucket.com/albums/oo69/HereinHalifax/2012-01.jpg
Feb – http://i362.photobucket.com/albums/oo69/HereinHalifax/2012-02.jpg
Mar – http://i362.photobucket.com/albums/oo69/HereinHalifax/2012-03.jpg
Apr – http://i362.photobucket.com/albums/oo69/HereinHalifax/2012-04.jpg
May – http://i362.photobucket.com/albums/oo69/HereinHalifax/2012-05.jpg

The blue line is our mean daily temperature, with the left axis being 
°C; the right axis is kWh and each column represents the combined usage 
of these units on that particular day.

BTW, we've been selected to participate in PowerShift Atlantic's test 
project (see: 
http://www.nspower.ca/en/home/environment/powershift/residential.aspx ; 
see also: http://www.powershiftatlantic.com/). If the results prove 
favourable, electric water heaters throughout Atlantic Canada could be 
used to store excess wind energy during times of low demand and cycled 
on and off intelligently whenever the power system is under critical 
strain. This will hopefully allow us to add more renewable energy to our 
generation mix beyond what would be possible otherwise with respect to 
grid stability.

Regards,
Paul


On 7/20/2012 4:49 PM, Richard Garbary wrote:
>   Paul:
>
>   Awesome hack! It's too bad the ability to  de-rate wasn't a built-in
>   feature. Yesterday, I took out the timer for our 60 gallon Rheem and
>   replaced it with a digital touch screen dimmer. I've set it for 25%
>   meaning bottom element is 94 watts and the top 188 watts (fast
>   recovery!), for a max consumption of 4.5 kwh per day. In the summer,
>   4.5 kwh usage is about right. I may need to adjust accordingly. I'll
>   post some new charts over the next few days. The spreadsheet gives the
>   % output and corresponding kw numbers.
>
>   http://flatteningthecurve.wordpress.com/
>
> Here's a link you may find of interest:
>
> http://people.cs.umass.edu/~irwin/smartcap.pdf
>
> Richard