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Re: [Killietalk] PVC air manifold vs. lots of airline tubing

I think the $189 pump is only 26 watts. I've heard that that is the 
maximum and that they self adjust to lower usage if the demand is lower, 
which the piston pump for sure will not do.

Your still pretty close on the calculations:

75*24*365/1000=657 KWh

26*24*365/1000=227 KWh

Savings of LP is 430 KWh per year.
@ .16 per KWh, savings is $68.80 per year, so payback is a bit less than 
3 years.

I think that my 26 watt LP would pump more than 2 of the double pistons, 
so if you needed that much air, the payback would be $173.92 in a single 
year, which is very close to the cost of the pump. I left the 
aggravation of maintaining those old dynamasters out of the equation, 
but that must be worth something. The only maintenance the LP pumps need 
is an occasional cleaning of the air filter.

Can you tell I like my LP?

Dennis

Bill Shenefelt wrote:
> The  smallest Jehemco linear is $189 and consumes 32 watts.  Your double 
> piston is 75 watts.  (not sure of its volumetric output versus the linear 
> though.  For 43 watts (at 16 cents a KWH) to cost $189 it will take 3 or 4 
> years   Figure a kilowatt hour a day saved.    Much nicer pump though. 
> Almost inaudible.  Operational costs for the linears is about half of other 
> pumps of similar capacity.  Other than operational cost, the biggest 
> difference between a piston and a blower for bigger fishrooms is the 
> forgiveness for overdrawing air.  A piston pump is a unit that tries to pump 
> a volume.  Once you reach that volume, the pressure dies quickly with each 
> additional outlet.  A blower has a gradual decline in pressure as you 
> increase the number of outlets past its maximum anticipated load.  If you 
> know for sure the maximum number of outlets, a linear is great.  If you keep 
> expanding after you buy it, you may need to add another in short order. 
> Moral is :  Buy one a lot bigger than you need if you go linear and ever 
> anticipate expanding the fishroom.
> Bill Shenefelt
> http://sheneskillies.com 
>   

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