How Long to Run a Variable Speed Pump

[BryanR]

Hello Everyone. I'm new to the site here and what brought me here is a debate on how long I should run my pool pump in my new salt water pool in Houston, TX.

I have a 20'x40' pool, with a model 6060 boster pump controlled by an Omnilogic system and Variable Hayward Century pump. My Pool Builder set scheduled run times which run at variable speeds throughout the day; however, I have spoken with several other pool builders and pool cleaners who say I only need to run the pump 5-8 hours per day. What is everyone's opinion?

Thanks
Bryan

 

[mas985]

If that. For many, 3-4 hours is enough. The only thing that is mandatory is getting enough FC in the pool. After that, run time is only for removing debris and sometimes heating, both of which are purely optional.

 

[BryanR]

If that. For many, 3-4 hours is enough. The only thing that is mandatory is getting enough FC in the pool. After that, run time is only for removing debris and sometimes heating, both of which are purely optional.

I like that.. The PB said it takes more electricity to stop and start the pump then to run it at low speed all day except when running the cleaner. thank you.

 

[marcgr]

I like that.. The PB said it takes more electricity to stop and start the pump then to run it at low speed all day except when running the cleaner. thank you.

Someone doesn't quite understand... Starting and stopping the pump does take a lot of current but only for a second. It would have a negligible effect on your power bill. So a few on/off high-speed cycles throughout the day isn't going to be any more power than one longer high-speed cycle if the total pump run time is the same.

However, running at higher speed does take more current than running at low speed - the pump is more efficient at lower speed. So run at high speed for just long enough to get what you need from the chlorinator and cleaner (as MAS985 said) - in a few cycles per day if it makes you happy - and then at low speed to turn over water and get filtration.

High speed vs low speed is kind of like the difference between driving 80MPH or 50MPH. Low and slow takes less fuel. In a car you drive fast because you've got places to be, but your pool pump is always at the poolside...

Also be nice to your city utility and don't run your pool pump during peak air conditioning hours (usually 4-6PM).

 

[MarkTX]

However, running at higher speed does take more current than running at low speed - the pump is more efficient at lower speed. So run at high speed for just long enough to get what you need from the chlorinator and cleaner (as MAS985 said) - in a few cycles per day if it makes you happy - and then at low speed to turn over water and get filtration.

High speed vs low speed is kind of like the difference between driving 80MPH or 50MPH. Low and slow takes less fuel. In a car you drive fast because you've got places to be, but your pool pump is always at the poolside...

What he said ^

According to the Pump Affinity Laws, power consumed is proportional to the cube of the pump's speed. So slowing down a pump by a factor of 2 reduces the power consumed by a factor of 8. In other words, run half as fast for twice as long and you will filter the same amount of water, but at roughly 1/4 the power cost. However, running the pump slower will agitate the water less, so maybe less skimmer action will result. You can Google "Pump Affinity Laws" for much more information. Here is a nice article relating directly to swimming pools http://www.nrel.gov/docs/fy12osti/54242.pdf. I realize your question was "how long?" not "VS versus single speed?" but the speed at which you run the pump factors in.

 

[BryanR]

thank you for the info. i'll check out the article. I have a variable speed pump so I could run it on the lowest speed for most of the time except for when I have the polaris running.

 

[mas985]

Just for clarification. The pump affinity laws do not take efficiency into account so the power formula is really only relevant for power deliver to the water (aka hydraulic HP). The power consumed by the motor includes this power but also includes power used by the drive electronics, power wasted by heat and power lost to wet end inefficiencies (re-circulation loss and friction loss). So operating at the lowest RPM is not very efficient. In fact, below about 1000 RPM efficiency drops rapidly so you really don't want to operate much below about 900 RPM.

 

[otter86753]

In fact, below about 1000 RPM efficiency drops rapidly so you really don't want to operate much below about 900 RPM.

I run mine at 1000 RPM most of the time with four scheduled skimming 2500 RPM bursts throughout the day. On those few nights we have a freeze warning, I run the pump at 450 RPM; are you saying I use more overall electricity any time I drop below 900 RPM?

 

[mas985]

No, what I am saying is that the pump efficiency drops as measured by gallons pumped per kwh. So basically, as RPM drops below about 1000 RPM, the energy use of the pump levels out while flow rate keeps decreasing. So you don't benefit as much with a lower RPM.

 

[otter86753]

OK. In my case efficiency isn't my main priority. Thank you.

 

[BryanR]

I dropped to 100% variable speed for 5 hours a day and run my cleaner for 2 of those hours. It has dropped my electricity by roughly 10%.. not a big deal but it's something. I'm sure when it's warm enough and we are using the pool more we increase the cycle time.

 

[mas985]

Why a 100%? Nothing should require 100% speed. Have you tried other speeds?

And you really shouldn't need more than 5 hours even with usage.

 

[dpayne702]

My system is similar to yours. At what low speed percentage do you run your pump? For how many hours? My UV has a valve controlling how much water passes through the light. The valve is after the light. The builder had the valve opened about 10%. Should I open the valve 100%? I asked my pool guy and he wasnt sure. Thx for your in put

 

[CaveDiver86]

Recently I have been running 2000rpm for 6hr a day. I'm still tweaking the SWG chlorine sweet spot. I get small bubbles if I run at low rpms like 1250. I also only lose water when the pump running so I don't go for the low and slow method. If I run a solid 24hr I can lose an inch. If I run 6hr I loose 1/4". I must have a leak but none the less that's what I run mine.