Is there an advantage to a 2 speed or variable speed

[RobbieH]

Is there an advantage to a 2 speed or variable speed pump on a pool with no spa, suction side cleaners, etc.? I can see where a 2 speed might have an advantage in power consumption, but wasn't sure what the advantage would be for variable speed.

My pump appears to be very old, and I'm guessing very inefficient. I can try to get some numbers off it for reference, or maybe a picture, but I don't recall seeing anything that would help on it. I'm wondering if it's just sitting burning energy at a rate that would pose a scenario where a new pump would pay for itself in less than a year.

 

[JasonLion]

A variable speed pump will save even more electricity than a two speed will. However, the two speed gets most of the savings, so the extra savings often won't pay the extra cost of a vaiable speed (unless you pay a lot for electricity).

Payback time depends on how oversized your current pump is and how much you pay for electricity.

 

[BlueWave8]

Just wanted to throw this in:

Payback also depends on how long you run your pump. Most people have the option of only running their pump for 6 or 8 hours, which saves lots of electricity, so pump runtime isn't usually considered when looking at variable speed vs. 2 speed.

But in my (admittedly, very rare) situation, I do not have natural gas available at my house, and my pool is heated with a geothermal heat pump. The upside to this is that the geothermal heat pump uses very, very little electricity to heat the pool. The downside is that it equates to a very small BTU output, so my circulation pumps need to run 24x7, and since my pool is indoor, 24x7x365. So for my particular situation, it was a no brainer to put variable speed pumps on my pool and spa.

 

[RobbieH]

Thanks BlueWave, seems I didn't throw in enough information!!!

I can run my pump anytime. My electrical costs are always the same, 24/7. It's about 12 cents per kWh (not bad).

I'll get photos of my existing pump when I get home. Right now I'm running it 8 hours per day since my robot is dead still and I'm having to sweep daily to the main drain to keep the pool clean. Also, I have a ton of pollen and cottonwood tree crud falling into the pool, only one skimmer, and no other pool cleaning equipment other than me going out daily to skim the junk off the surface.

I'm not sure how much head I have on the system, and it may be hard for me to calculate. The pool has 4 returns of what I'm estimating to be 1" to 1.5" each. I'll get an accurate measurement while I'm getting the pictures of the pump. These returns are probably over 20' from the pump, again I'll get accurate measurements when I get the other items.

I have a pool heater, but I will NEVER use it. In fact, I'm going to take it out of the system and sell it for scrap. I'll get a picture of this old Teledyne gas unit for you, it is ancient! I have no need to heat my pool IMO, and it would cost a fortune to use even if I wanted to. My neighbor has a smaller pool than mine and it costs him about $1,000 a month to heat his pool, and the temp increase is minimal. I'm already up to 76 degrees, even with all the rain we've had, and it'll be in the mid 80's soon.

 

[acroy]

I did the math on replacing my older 2.25hp (total) pump with a 2spd motor - with 8hr runtime, paypack period is about 12months assuming 8hrs/day full speed on the old pump vs. 6hrs low / 2hrs high on a new 2-spd pump. This assumes $0.10 per kWh.

For heating the pool - I've had great luck with a few 15' diameter plastic 'solar covers' on the pool: around $20/ea, helps the pool capture & retain heat well. We were swimming into mid-November last year before the pool got much below 70F.

Enjoy!

 

[susa]

>>..an advantage to a 2 speed or variable speed pump ..

lots of factors come into play. for example, the price factor for cost of power varies and with a variable fixed speed motor one can do all kinds of things, instead of being locked into just *this speed* or *that speed*. once I started digging into the programming behind the scene of the VF components, there appears to be no limit to kinds of things I can do with the system.

one example: currently I run a 4 hour *poolvergnuegen+IntelliChlor+Simpool pH* cycle at 185 watts for 4 days a week, a 5 hour *slowpoke* filter only cycle at 140 watts (no cleaner motion, IntelliChlor Off, Simpool pH Off) and for 3 days a week I run 24 hours a day at ~90 watts at *ultraslowpoke* speed (only pump and filter are On).

entire house is being monitored with a ted5000 unit so I know precise power use down to the second,minute,hour,day resolution.

there are other things I do with the programming but those are the main features to illustrate flexibility.

one of the best things I like is the silent turn on/off/runtime of the pump, even priming startup can be adjusted in such a way that the system primes silently so I can never hear audibly that the pump is on, just the ripples across the water surface tells me it is running. mine is also setup on antivibration mat so it makes no sounds and I have to physically walk over to the equipment to notice just an occasional note from the Simpool injector being activated.

 

[RobbieH]

My pump is very noisy, and I would like it to be quiet, but since you can't hear it at the pool now, it's not a big part of the equation.

Someone told me that a pump like mine can pull 1200 watts when running. I won't ask if that's accurate since I don't have the model up yet.

 

[douglee25]

My pump is very noisy, and I would like it to be quiet, but since you can't hear it at the pool now, it's not a big part of the equation.

Someone told me that a pump like mine can pull 1200 watts when running. I won't ask if that's accurate since I don't have the model up yet.

Absolutely! Take a typical pump that draws around 7.5 amps at 220v. Power (watts) = Voltage x Amps. Therefore, 7.5 amps x 220v = 1650 watts.

Doug

 

[RobbieH]

Here we go:

I haven't looked to see if it's wired 110 or 220 yet. There is 220 in the garage, nearby. Seems to me it would make more sense to run it 220.

 

[douglee25]

The wattage running that motor at 110 vs. 220 is basically negligible. Therefore no cost savings will be realized either. Technically speaking 220v will provide easier motor starting vs. 110v, but again you will probably never notice in a pool pump.

Doug

 

[RobbieH]

Thanks.

I'm trying to read the date code, but I can't find anything online that matches that G91.

I was able to find that P2RA5 pump online, but no specs.

 

[douglee25]

Thanks.

I'm trying to read the date code, but I can't find anything online that matches that G91.

I was able to find that P2RA5 pump online, but no specs.

G=July
91=1991

Is that a possibility if you had to guess the age of your equipment?

Doug

 

[RobbieH]

I found a receipt for the sand filter for 1989 (I recently replaced it). I wouldn't be surprised for 91 for the pump.

I just realized I forgot to post this. It is on the back side, so I never noticed it before. Is that something that got spilled on the pump? Sure looks like it. I don't THINK anything could come from there?

 

[mas985]

Technically speaking 220v will provide easier motor starting vs. 110v, but again you will probably never notice in a pool pump.

Where did you here that? Technically, there is no difference at all in the motor when feeding with 110v vs 220v. The pole windings are fed in series for 220v and parallel for 110v. The same voltage is across each pole and the same current is traveling through each part of the winding either way.

The only difference between 220v and 110v is wiring that is used to connect to the pump. The current is twice the amount in 110v vs 220v but that has nothing to do with the pump.

 

[RobbieH]

I believe he was thinking of 3 phase. 3 phase motors do start easier, don't even need a start capacitor. Believe it or not, my house has 3 phase! It's being used for the ancient A/C compressor now, but since I plan on having a NICE shop in a few years, it may come in handy!

 

[douglee25]

Technically speaking 220v will provide easier motor starting vs. 110v, but again you will probably never notice in a pool pump.

Where did you here that? Technically, there is no difference at all in the motor when feeding with 110v vs 220v. The pole windings are fed in series for 220v and parallel for 110v. The same voltage is across each pole and the same current is traveling through each part of the winding either way.

The only difference between 220v and 110v is wiring that is used to connect to the pump. The current is twice the amount in 110v vs 220v but that has nothing to do with the pump.

Less amperage on a 220v motor will provide easier starting and cooler operation. Again, on a pool pump motor you would never see a difference.

Doug

 

[mas985]

But inside each of the motor windings, the amperage is EXACTLY the same with 220v vs 110v. The amperage is only different OUTSIDE the motor. Efficiency and heat loss is exactly the same in the motor. The only difference is outside the motor.

 

[douglee25]

Correct. If you run double the amperage through a single wire vs half the amperage through two wires, there will be a difference in motor startup. Think of a table saw wired with 110 vs 220. Which one starts up quicker?

Doug

 

[chem geek]

110V Configuration with two windings connected in parallel

.......................................... /--- 10 Amps @ 110V -->\
.......................................... | ........................................ |
20 Amps to the motor --->| ........................................ |---> 20 Amps returning from the motor
.......................................... | ........................................ |
.......................................... \--- 10 Amps @ 110V -->/

.......................................... |<------- 110 V ------->|


With each winding having resistance R, the input current is split in half with the same voltage across each winding. Power in each winding is I²R = 100*R so total power is 200*R.

220V Configuration with two windings connected in series:

10 Amps to the motor -----> 10 Amps with 110V drop -----> 10 Amps with 110V drop -----> 10 Amps returning from the motor
........................................ |<--------- 110V ---------->|<--------- 110V ---------->|
........................................ |<------------------------ 220V ----------------------->|

With each winding having resistance R, the input current is the same in each winding, but the voltage drops by half in each (i.e. the voltage across each winding is half that of the input voltage to the pump). Power in each winding is 100*R so total power is 200*R.

Power and heat in each winding is the same in both configuratons and total power is the same as well. Only the wiring to the pump as well as the wiring in the pump to the windings is affected by the difference in total incoming current. [EDIT] See correction by Mark below; the configuration split is done at the terminal block so there is no internal wiring carrying the full input current in the 110V parallel configuration. [END-EDIT]

 

[RobbieH]

OK, now, how inefficient is this pump compared to what's out there today?