Wednesday, August 1, 2012

Energy Audit

I'm writing this to get my head around what I've just found out.  I hope it provides you with food for thought.

I've noticed our electric bill climb as I continue to add to my aquaponic systems, so using a Watt meter I did an energy audit .  
The first thing to surprise me is the cost of moving air.   I'm using a whole house fan and a 20" box fan.  Both use more than I expected.  The whole house fan consumes 530W, and the box fan 90W. 

My submersible pumps are not too bad for submersibles, but one is not as large as I would like.
The Alpine Hurricane 2400 GPH is drawing 129W.  It is delivering 1750 GPH at 4 foot head.
The undersized 'No Name' pump I am using in the outside IBC system is drawing 20W and delivers 268 GPH at 4 foot head.

Expanding the grow beds in this IBC system is going to require a larger pump, so I just purchased an AZFlo 2400/4000 External Pump for 299.00.  It will deliver 1900 GPH using 105W at 4 foot head..  This is 20W less than the Alpine Hurricane delivering 1700 GPH.  If I were to replace that submersible with this external pump I would break even in 5.7 years.

Now here's something I find interesting.  Pump power usage is non-linear. These tables show as head increases GPH decreases as would be expected, but the Watts seem to peak around the midpoint of maximum head. 

I have also have a Sequence 3600 700 series pump on my pond.  139W delivers 2820 GPH at a 4 foot head.  As you can see the external pumps are a lot more economical.

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