Filter sucks air in at low rpm?

[proavia]

Interesting - why the 1000 rpm limit?

Below 1000 rpm, the effeciency of the motor drops drastically.

 

[Jimrahbe]

When the pump speed is reduced to below 1000rpm, the vacuum inside the pump basket is dramatically lowered. Because the vacuum in the basket is much lower now, the basket lid is no longer being pushed down the way it was before, this in turn causes the o-ring to not have the same extreme sealing effect as it did before with much higher speeds.

David,

That is also my theory and why I never worry about a small amount of air under the pump lid as long as it does not keep getting bigger and bigger.

Thanks for the insight..

Jim R.

 

[proavia]

Side thought - does that mean at low rpm of water can exit filter faster then the pump can fill it that it effectively causes a pulling effect of the water rather than a pushing effect? More like a siphon by the returns? (Which I have 6 of).

In a closed/sealed system - no.
Only when you open the air bleed can this happen.

 

[Jimrahbe]

Interesting - why the 1000 rpm limit?

BDY,

The whole point of running slow is to save on your electrical bill.. In my tiny mind, I believe that once you go below 1000 RPM you are not really saving much and skimmers are less likely to be working well. I run 24/7, mostly at 1200 RPM, for less than $20 bucks a month. How much of that $20 could I possible save by running slower?

One size does not fit everyone, so you just need to set things so that they work well for you, and your pool. Most of my recommendations are based on what works well for me.

Thanks,

Jim R.

 

[BDY]

BDY,

The whole point of running slow is to save on your electrical bill.. In my tiny mind, I believe that once you go below 1000 RPM you are not really saving much and skimmers are less likely to be working well. I run 24/7, mostly at 1200 RPM, for less than $20 bucks a month. How much of that $20 could I possible save by running slower?

One size does not fit everyone, so you just need to set things so that they work well for you, and your pool. Most of my recommendations are based on what works well for me.

Thanks,

Jim R.

I would rather trust the collective experience than my own newbie judgement

Having said that how do you calculate the
Bill? Do you take the watts the motor says at that speed and multiply by hours/days/bills?

B

 

[mas985]

I don't think anyone has asked this question yet but it can explain why air sucks into the filter at low RPM. What is the height of the filter relative to the pool water level?

If the filter is fairly high relative to the pool water level, the top of the filter can be below atmospheric pressure even with the pump running. The RPM of the pump determines the pressure at the top of the filter but it is not always above atmospheric.

 

[proavia]

Let's say the pump uses 100 watts per hour and runs for 10 hours per day. That equals 1000 watts per day or 1 kW.
If your electric rate is $0.15 per kWh, it costs you $0.15 per day. $0.15 per day times 30 days equals $4.50 per month.

 

[Rocket J Squirrel]

Now this has me wondering. I set my Intelliflo to run at 850 RPM in freeze mode just to keep things moving a little. Now I wonder whether this speed is too low and might suck air into my filter. I'm not out there to look at the pump lid when it's 34° at 4 AM.

 

[Jimrahbe]

Let's say the pump uses 100 watts per hour and runs for 10 hours per day. That equals 1000 watts per day or 1 kW.
If your electric rate is $0.15 per kWh, it costs you $0.15 per day. $0.15 per day times 30 days equals $4.50 per month.

What Gene says above..

When I run at 1200 RPM my system reports about 196 watts. I use $20 bucks because it is a nice round number and not everyone has the same low electrical rates I have. Keep in mind that I have an older IntelliFlo and the newer ones are even more energy efficient.

Thanks,

Jim R.

 

[BDY]

What Gene says above..

When I run at 1200 RPM my system reports about 196 watts. I use $20 bucks because it is a nice round number and not everyone has the same low electrical rates I have. Keep in mind that I have an older IntelliFlo and the newer ones are even more energy efficient.

Thanks,

Jim R.

Mine says 71 watts at 1000 rpm and 1084 watts at 2700 rpm. I’m calculating 14$ a month!

This will pay for itself inside a year i think - the PB wanted a 1.5 hp single speed and based on your guys advice least year I forced the intelliflo…

 

[BDY]

I don't think anyone has asked this question yet but it can explain why air sucks into the filter at low RPM. What is the height of the filter relative to the pool water level?

If the filter is fairly high relative to the pool water level, the top of the filter can be below atmospheric pressure even with the pump running. The RPM of the pump determines the pressure at the top of the filter but it is not always above atmospheric.

The filter is ground level relative to pool so i would guess 5.5 - 6’ above water line.

 

[mas985]

The filter is ground level relative to pool so i would guess 5.5 - 6’ above water line.

Since a typical filter is 3' high, that means the bottom of the filter is 3' above water level? Is your equipment pad 3' above water level or close to water level? If the pad is close to water level, the top of the filter would be about 3' above water level.

 

[JamesW]

https://www.pentair.com/content/dam/extranet/nam/pentair-pool/residential/filters/clean-and-clear-family/clean-and-clear-plus/clean-and-clear-plus-guides-manuals/clean-and-clear-plus-install-guide-english.pdf

 

[mas985]

So if the relief valve is 6' above water level and for a typical pool setup with 2" plumbing and cartridge filter, a pump RPM of below about 1200 RPM will result in a pressure below atmospheric at the relief valve.

 

[BDY]

That makes sense then…. Thanks so much.

 

[JamesW]

Run at a higher speed to purge the air and then lower the speed with the air relief closed.