Energy Efficient Pool Pump?

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chem geek
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Postby chem geek » Tue 20 Jan, 2009 12:55

That's good that the solar panels have 2" headers. Your electricity costs are very low so if you save 1000 Watts (and you could save 1500 Watts) when the solar is on, then that's 6.5 cents per hour so that's about $15 per month if you were running the pumps 8 hours a day. In addition, you would save another 2000 Watts or so when the solar is off which may be 2-4 hours per day so about $8 to $16 per month in additional savings. So with your low energy costs, it will take a lot longer to achieve payback for a new pump and piping. In my pool, my marginal electric rates were about 32 cents per KWh so I was saving about $600 per year -- your savings obviously won't be that high at perhaps $200 a year or thereabouts. [EDIT] If you run the pump during the off-season (winter) with the solar off, then the Intelliflo and 2" pipe will save about another $100 so the overall per year savings is around $300. [END-EDIT]

It's not clear if you will be able to get that much more than 60 GPM from the single Intelliflo pump even after replacing the 1.5" pipe. It will certainly be far less energy than the two pumps, but you might not get that much higher a flow rate. Even if you did get to 75 GPM, the difference in efficiency in the solar panels isn't huge. Faster flow rates are more efficient in solar heating, but it's diminishing returns.

You can see in this Fafco SunSaver spec in the "EFFICIENCY vs. FLOW" chart the drop in efficiency at lower flow rates. For this panel, 4 GPM is recommended and yields 80% efficiency. For your panels, 60 GPM vs. 75 GPM would be like 3.2 GPM in this chart so perhaps 76-77% efficiency compared to 80% so perhaps 5% less efficient. So if after getting 2" pipe and a Pentair Intelliflo you were able to get up to 75 GPM, then the heating would be 5% faster -- not that much. You'll find a trade-off in energy savings vs. this efficiency.

[EDIT] By the way, what do you have for a pool cleaner? Does it have yet another pump -- a booster pump for a pressure-side pool cleaner? [END-EDIT]

Richard


Rick Sass
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Postby Rick Sass » Thu 22 Jan, 2009 22:33

Richard -

Regarding your questions:

1. I run the pump during the summer and winter for 8 hours/day and solar is enabled during the summer and winter as well.

2. I do not have a pressure-side pool cleaner. I'm using an AquaJet robot cleaner.

3. So, after all this analysis, it appears that swithing to one InteliFlow pump and replacing the 1.5" piping with 2" piping will require a longer payback period with a very minimal amount of solar heat efficiency - is that correct?
chem geek
Pool Industry Leader
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Posts: 2382
Joined: Thu 21 Jun, 2007 21:27
Location: San Rafael, California

Postby chem geek » Fri 23 Jan, 2009 00:03

Yes, due to your low electricity rates, the payback period is longer. Using the presumed flow rates from your two pumps through your system, will show little INCREASE in solar efficiency -- I wouldn't say that you are currently at minimal or low efficiency, just that the new system won't increase the efficiency by very much -- it mostly just lowers energy costs.

Since you are running year-round, your energy savings would possibly be around $400 per year. The Intelliflo pump you can get for around $800 or $1200 depending on the variable speed or variable flow model. You can get the former plus install a flow meter and do OK. You'll also need an IntelliComm module for around $350. These prices do not include installation.

According to the Florida electric rates I see here , the rate appears to be closer to 10.5 cents per kilowatt-hour. If that were the case, your annual energy savings could be closer to around $650 per year. How much you actually saves depends a lot on how long your solar is on per day (I assume the solar booster pump only runs when the solar is on) and I assume that your solar turns on via some thermocouple measurement (i.e. when the panels are warmer than the general pool water).

Richard

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