Intelliflo/legend II problems

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RonI,

Something does not make sense to me. At 3160 RPM, you are running at 45 GPM? According to the Intelliflo head curves, you have about 78 feet of head. That is a lot of head loss for just 45 GPM. Some could be the solar panels and some the returns.

Your PSI indicates that you have about 58 feet of head just on the return side which means about 20 feet for the suction side. Both seem high to me.

For kicks, I modeled the Intelliflo pump with my plumbing in a spreadsheet I have and to get 45 GPM requires 1560 RPM. With my solar on, it would be about 2100 RPM.

Can you shut the solar off to see what the RPM and PSI are? This might tell you if most of the head loss is in the solar or returns.
 
I think from your previous posts, you said that you have 2.5" suction side plumbing and 2.0" pressure side plumbing. This is the same size plumbing that I have but you seem to be experiencing very high head loss.

Your latest numbers indicate a total head loss of 63 feet at 45 GPM with 42 feet for the return and 21 feet for the suction.

It is as though you have 1.5" plumbing instead of 2"/2.5". For the plumbing size you have, you should be experiencing much lower head loss. There must be some extra head loss somewhere in both the suction side plumbing as well as the return side plumbing. Do you have any valves that are not entirely open somewhere?

The only thing I can suggest is to run at lower GPM. If you halve the GPM/RPMs, you will be running at a more efficient speed. However, this could present a problem for your cleaner and you may need to readjust for that.
 
Those are the correct pipe sizing at the equipment. I have a 2.5" line for the skimmer and a 2" suction line for the cleaner. The return is 2" for the spa return and 2" for the pool. The pool return has roughly 50 feet of 2" line from the equipment converting to a estimated total of 70 feet of 3/4" pipe for the 3 pool returns. I appreciate your help here as I don't fully understand all of this hydraulics. I ended up getting a robot cleaner so I was thinking was converting this dedicated 2" suction line to a pressure return but was wondering if this would help. I guess it can't hurt though.

I'm seeing the same sort of issue at the spa too. For my spa setting, I put in 35gpm and the pump runs up to 3100rpm. This spa has 3 3/4" returns for the heated water with 2" suction lines.
 
It is likely that the 3/4" lines are causing most of your head loss and thus your efficiency loss. Another 2" line would probably help.

Also, I suspect that your pressure guage is not reading the correct pressure either which is not uncommon. Based upon the plumbing you have, most of the head loss should be on the return side. At 45 GPM and 2860 RPM, the plumbing should have 63 feet of head. Since you have 2.5" plumbing on the suction side, there should be very little head loss compared to the returns. So if we leave 3 feet of head for the suction side, the return is left with 60 feet or about 26 PSI.

How old is the guage and how confident are you in the reading?

If the guage is correct then suction side must have fairly high head loss as well. But that would be unusual for 2.5" plumbing.
 
I assume your talking about the gauge on the filter. The pool is only about couple of months old. I can't really imagine that the suction side has much head loss since it is pretty much a straight run to the equipment pad. The suction side currently has a 2.5" and a 2" pipe coming to it at the equipment pad. I guess I am a little confused on how you can do any calculations based on psi. As the filter gets dirty, the psi rises so are these calculations based on a clean filter? Do DE filters have require more water pressure than other filters? Can there also be some sort of blockage in the filter too? The readings that I have been giving you aren't with a clean filter. It hasn't been backflushed in a couple of weeks or so. I'll try and backflush the filter tonight when I get home from work to see if it makes any difference.
Thanks for your help, I really appreciate it.
 
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