Pool motor

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Old 07-17-18, 12:10 PM
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Pool motor

Hello,

My son just bought a house with a pool. The seller said she ran the motor continuously during the season. She even removed he pins from the timer. The guy at the pool supply store said not necessary, the filter should run 8-12 hours per day. My son is freaking out about the electric bill (which hasn't come yet). So.....being a good dad I figured I would ask the experts here.

The basic question is: if the motor in the picture runs all the time, what is the equivalent number of 100 watt light bulbs? 1? 100? 1000?

Thanks.

 
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Old 07-17-18, 01:02 PM
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The motor could draw as much as 2'200 watts or 2.2kw. If your son looks at his power bill he can see how much he pays per kwh he can figure out how much it costs per hour to operate. If it's $.10 per kwh the it will cost about $.22 per hour to operate the pump.
 
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Old 07-17-18, 01:13 PM
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Thanks boss....the rate is 12.82

I will let him know so he can do the math. After all I paid for most of his college LOL
 
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Old 07-17-18, 01:54 PM
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Originally Posted by Pilot Dane View Post
The motor could draw as much as 2'200 watts or 2.2kw.
Maybe I'm missing something here, however the label on the motor says that the power consumption is 1.1KW. Why are you stating that the consumption is double that (2.2KW)?
 
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Old 07-17-18, 02:37 PM
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I agree with Bob. For continuous operation simply multiply the electrical rate (cost per kilowatt-hour) by 1.1 to come up with the cost of operation per hour of use.

Note well that some utilities have a flat rate structure (same cost per kWh regardless of total kWh's consumed) and other utilities will have a graduated rate structure that changes the cost per kWh depending on the total consumption over the billing period. These latter often will have a "block" of power at a certain cost and if the consumption exceeds that block they have an additional block of power at a higher cost up to a certain total and then maybe a third and possibly fourth tier that increases the cost per kWh of the higher blocks. It can get pretty complicated trying to calculate the total electric bill (or any specific usage) with these latter rate structures.

Further, there could be additional charges for fuel cost adjustments, taxes and other items.
 
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Old 07-17-18, 03:59 PM
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I think you are correct. I did the max amperage x voltage to come up with the wattage. The 1.1 is probably more accurate for it's running power consumption.
 
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Old 07-17-18, 11:56 PM
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the filter should run 8-12 hours per day.
He's absolutely correct unless you have some heavy duty pool use.
I run mine a maximum of 12 hours a day and that is plenty.
 
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Old 07-18-18, 05:02 AM
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Nameplate HP rating on a motor is at the output shaft. Since motors are less than 100 percent efficient, your motor uses 2.1kw (nameplate voltage x current) to produce 1.5 HP (nameplate 1.1 kw). At 50 percent efficient. I would run it as little as possible. Your son's electrical meter spins at the 2.1kw value when the pump motor is operating.
 
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Old 07-18-18, 09:07 AM
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Thanks guys. I think we'll get the pins for the timer and run it 50% of the time.
 
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Old 07-18-18, 02:46 PM
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The 1.5 HP / 1.1 kW ratings are the mechanical output power of the motor.

The 230V * 9.3A = 2.1 kW is the maximum electrical input power to the motor.

The difference is what gets lost to inefficiency (heat).

In this case, the motor draws up to 2.1kW which in actual use depends on how much load is on the pump. The elevation head, pipe friction loss and back pressure from filtering elements will all effect actual energy use, but it should not exceed 2.1 kW. In most areas of the country I would estimate $0.15-$0.20 per hour but that could double in some expensive areas.
 
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Old 07-18-18, 05:15 PM
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@ibpooks: so......utlity rate of 12.82 cents / kwh and 1.1 kwh (from the label) works out to 14 cents per hour to operate ?.

Roughly $100 per month?

Is that right ?
 
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Old 07-18-18, 09:43 PM
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Unless I missed it, no one asked the most important question: how many gallons of water in the pool? That will inform how many hours per day to run the pump.

3450 RPM single speed is overkill unless the pool is huge. To save money long term, replace this beast with a modern variable-speed pump and run at lower speed.
 
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Old 07-19-18, 06:13 AM
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Also the type of filtration can have an effect on how long you run. I find 6 hours is fine for me running a DE filter.
 
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Old 07-19-18, 11:25 AM
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28k gallons per the pool supply store calculations
 
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Old 07-19-18, 11:28 AM
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The seller said it was a sand filter.......I assume that is similar to DE?.

I used to have fish tanks and used DE filters in those.
 
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Old 07-19-18, 07:10 PM
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My pool is 20'x40'x9' deep. Roughly 26k gallons. As I mentioned... I have almost the same exact pump you have. I just rebuilt it over the winter as the bearings were getting noisy. I'm guessing it's better than 20 years old..... probably closer to 25 years old.
 
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Old 07-20-18, 07:56 AM
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@ibpooks: so......utlity rate of 12.82 cents / kwh and 1.1 kwh (from the label) works out to 14 cents per hour to operate ?.

Roughly $100 per month?
Somewhere between $100 and $200 is a reasonable guess. How much power the pump actually draws depends on factors in the system like water pressure which we can only guess at. We do know the maximum is 2.1 kW * 24 hours/day * 30 days/month * 0.1282 $/kWh = $194 / month.
 
 

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