An interesting find. Been looking at the Gast 0823, 1023, and 1423 models of pumps,
They are rated 8, 10, and 13 cfm respectively, yet they all are rated at 56kw and pull about 5 amps at 230 volts. Hmmmmm. Weird.
So from strictly an electric standpoint, assuming all three would have one start cycle per day (where higher current flow for startup - running continuous it would not have that additional draw) it would be more economical to run the largest pump and run proportionately fewer hours per day, assuming the diffusers would stay within their operating parameters for cfm (or add another one or two diffusers if the larger pump had more flow than needed).
For example if the 0823 required 10 hours per day to get proper pond turnover, the 1023 could do it in 8 hours and the 1423 could do it in 6 hours 15 minutes. All with the same electric use per hour. So the 1023 should do the job on 80% of the electricity of the 823 and the 1423 should do the job on 62% of the electricity because of running proportionately fewer hours at the same 5 amp load.
Am I missing something? Seems strange. Seems like the higher cost of the bigger pump would pay for its additional cost in electric savings, not to mention longer life because it runs less total hours to do the job.
Gast rotary vane pump models Edit: calculating electrical cost for above pumps assuming 7 days a week 30 weeks per year .08 per kwh. 0823=$148 per year. 1023=$118 and 1423=$92. Not as big of difference as I thought. In a ten year life span 1023 pump would save 300 dollars over the 0823 and should have longer service life. 1423 would save $560 over ten years and should have even longer service life because of reduced running hours.
Of course a person would have to figure in the cost of capital....... well maybe that is farther than I want to go. Looks like the bigger pump is not a bad way to go assuming a person can effectively utilize 13 cfm (actually a little less than that at depth).
Energy calculator Edit: Ok, some of the above is wrong. Gast does a poor job of correctly listing the specs in their literature. On the main page all models are listed at .56kw although the 1423 is listed as a larger horsepower. Does not make sense because it is wrong. Downloaded the PDF data sheet and the 1423 is .75kw as it should be for 1 hp. So what I said above for the 0823 and 1023 difference holds true. The 1423 would use proportionately more electricity based on its larger motor. As it should. Be nice if they would get their literature correct.
The 0823 or 1023 pump run 27/7 for 30 weeks per year at 8 cents per kwh would cost about $355 to operate annually, if I figured it right.
