Suggestions on pump speed?

[derekt75]

I want to use the least amount of energy to use the solar heat for the entire day.

I have a brand new Intelliflo VS hooked up to a Zodiac iAqualink.
The solar is split into two levels, the peak of the top level is about 30 feet off of the water, while the peak of the lower level is about 20 feet off of the water.
My filter was just cleaned and is currently reading about 10psi at low pump speeds.

At 1550 RPM with the solar engaged, I don’t feel any water coming out. The Jandy AquaPure does report “Flow”, however (even after several minutes of me not feeling water going into the pool.)
At 1650 RPM with the solar engaged, I feel water moving, but you can hear some air in the system. I don’t see bubbles going into the pool, though.
At 2200 RPM with the solar engaged, I don’t hear any air.

Some questions:
1) Is it possible that at 1650 RPM that only the lower solar element is active, and the coils on the 2nd story roof are dry? If so, is there a way for me to know that the entire solar array has flowing water?

2) If the pump isn’t turning fast enough, can I destroy something in the AquaPure by running it when there’s no real flow of water? I would think that the AquaPure flow sensor would sense the lack of flow, but might this be fooled by a pump that’s kinda churning water without actually getting any real flow?

I’m also generally interested in recommended speeds when other devices are on.
For instance, when the gas heater is running, do I need to increase the pump speed so that the water doesn’t superheat?

Here’s what I currently have for speeds:

Solar Heat: 1900 (runs 9:30am to 6:30pm)
Pool: 1500 (only runs if solar panels aren’t hot enough)
Cleaner: 2850 (runs 1.5 hours twice a day) (In floor jets run off of separate single speed pump)
Pool Heat: 3000 (rarely used)
Spa Heat: 3000

Does this seem like a reasonable setup?

Is there any benefit to bumping up the pump to 3300 RPM a couple times a day to try to unstick any crud somewhere, or is that pointless?

Here's some data on RPM vs. Power for the pump.

solar off solar on
RPM Watts RPM Watts
1500 235
1800 389 1800 359
1900 454 1900 420
2000 482
2100 551

2750 1183
2850 1316
3000 1595

thanks,
Derek

 

[mas985]

There needs to be at least 15 PSI filter pressure (maybe more) to keep the vacuum release valve closed on the roof and you probably will need higher RPM to do that so 2200 RPM sounds about right.

As for ideal speeds, the most efficient speed is around 1000 RPM but the pump may not have enough flow rate for anything but filtering and chlorination. Everything else is going to be trial and error.

 

[jblizzle]

Also, note that the most efficient heating of the pool is done with as high of flow rates/pressures your panels can handle ... this is likely a much higher RPM. But if you do not care about how well the pool heats up, then lower RPM will certainly save you money.

 

[derekt75]

I do care about how well the pool heats up, but I thought that flow rate had little to do with the heat transfer.
I thought if I had 3 times the flow, the water would heat up one third as much on its way through for an equal amount of heat added to the pool. Is that not true?

 

[derekt75]

There needs to be at least 15 PSI filter pressure (maybe more) to keep the vacuum release valve closed on the roof and you probably will need higher RPM to do that so 2200 RPM sounds about right.

As for ideal speeds, the most efficient speed is around 1000 RPM but the pump may not have enough flow rate for anything but filtering and chlorination. Everything else is going to be trial and error.

Thanks Mas,
What happens if the release valve does not stay closed? I get air in the system? but then I'd see air bubbles coming out of the output jets, right?

 

[jblizzle]

I do care about how well the pool heats up, but I thought that flow rate had little to do with the heat transfer.
I thought if I had 3 times the flow, the water would heat up one third as much on its way through for an equal amount of heat added to the pool. Is that not true?

Absolutely not true. The higher the flow rate the better. Although the temperature difference will certainly be lower across the solar panels ... you are moving more water at that lower delta T which ends up adding more heat to the pool.

Lots of good info here if you look near the middle of the first page (read after linen first comments and then Jason's explanation):
solar-heater-performance-t50022.html?hilit=solar%20efficiency

 

[mas985]

What happens if the release valve does not stay closed? I get air in the system? but then I'd see air bubbles coming out of the output jets, right?

Right!