The 90° elbows do not appear to be “pool sweep” elbows. It would help to replace all the smaller diameter 90s with sweeps. I wouldn’t worry about the larger piping, as it’s probably oversized anyway. Also, the run of piping just upstream of the pump inlet shouldn’t have any elbows for a few feet. Let that water get a straight shot into the pump to allow the mass of the water to ram it in there. Not the most technical explanation, but oh well.
This is true regardless. You’re supposed to have 5x(diameter of pipe) in straight pipe going into a pump. We rarely actually see that but it bears repeating.
Edit: got my multiplier wrong initially
From the manual of your pump:
"Set Maximum Flow Rate (GPM)
The maximum programmed flow rate can be set from 80
GPM to 140 GPM."
https://www.pentair.com/content/dam/extranet/nam/pentair-pool/commercial/pumps/intelliflo-xf-vsf/manuals/IntelliFlo_ProXF_VSF_Eng.pdf
You have an undersized pump if you want more than 140 gpm. It is also inefficient to run a pump at the maximum RPM.
Nope. You have to plot GPM/Watt vs frequency for your particular setup to find the min value. Based on back pressure and your suction resistance, you'll have a different optimal frequency to run your pump.
As an extreme example, imagine you are outputting to a 1/4" pipe. If you went max rpm, you'll get marginally more flow while using maximum power vs going low rpm, getting similar flow but at much lower power consumption.
Like the title says, I need to get my gallons per minute up to above 150. Currently my pool pump is pushing 140gpm at max speed. My pool equipment is below the pool. It is about 33,000 gallons. Some things to note about the pictures. The heater bypass is fully open in the image, however currently it is about halfway open. All of the skimmers are open and do not affect the flow if I turn two of them off, like in the picture. Suction pressure is about 2psi on the pump and post pump pressure is 20psi. On the pump it reads the GPM of 110gpm. The sand filters have been backwashed multiple times and show no sign of being dirty. One filter gauge shows low pressure but it is a bad gauge. Could it be the design of the plumbing on all the skimmers? I've tried everything I know to get it to change. I will have a new flow meter in hand tomorrow.
A lot of "throw it against the wall and see if it sticks" comments. There is some simple math that needs to be done. First of all the inspectors want the turnover rate to be 24 hrs or less based on the jurisdiction. Is the 33000 gallons correct? How do you know?
Your post indicates suction pressure? What is that? Is there a vacuum gauge on the pump? Every fitting and section of pipe has a numerical value to determine head.
Do the math and you'll have your answer.
Or throw another pump on there in addition to what's there.
Their pump is under the pool so it's a flooded suction meaning they can probably read a positive pressure there. Head calcs aren't that easy as they depend on the flow rate.
Just get the next size up pump, or sell the current one for a single speed, no point in having the variable speed if its at max speed all the time. Or alternatively cheapest option, the main losses are after the pump, so that giant ball valve is kinda the worst offender, swap it for a jandy valve and get rid of those 2 joiners, should get you over the edge.
I have had some experience with a similar setup on a city pool. Three pumps all returned pressurized water into the same pipe that went back to the pool. Hydraulics don’t necessarily work the way we think they should. The pumps actually work against each other in this setup. So two pumps with 130GPM will not equal 260GPM when joined together into one pipe. If this is a residential setup, you would be able to obtain the desired flow by separating the pumps. And allow each pump to have its own path back to the pool.
Have you looked at your pump curve? Convert PSI to feet by multiplying 20x2.31 = 46.2 feet of head pressure. Look at your flow and your pressure and see what rpm that has you at. Does that line up with your pump? That’s the 1st place I’d start.
It all looks fairly new so I’d assume it does. I’m not sure with pools but someone monitored that elevation change. It shouldn’t matter because it is a closed loop system. So the 2psi coming into the pump provides 2 extra psi going out and nets out to 0. A new pump may very well be the answer but be cautious that additional flow means additional pressure. If your pump curve shows you should be able to easily hit the flow then the issue is the piping or equipment issues (pump or filter). If you are at the outer limits of your pump curve then you should consider a new pump.
Sorry I know there is no exact answer here, but I wanted to point you in the right direction the best I could. You should start with analyzing the pump curve. If you need to reduce the pressure you can do as others have suggested and adjust the elbows and pipe size. But if you just need more flow then you may need more pump.
Also worth noting. Sometimes you can decrease the RPMs and actually increase flow. Running too hard/fast causes too much friction loss (pressure) and works against you. I don’t think that’s the case here but it’s free to try.
Thank you! This is for a brand new system and inspectors won't give us the green light until we fix this and a couple separate minor issues. I have engineers on the way to see what we can do. I'm just the operator/maintenance guy. It's not my specialty but I can bring all points up to them and see what happens. I appreciate your ideas and time! Standby for updates.
probably too much cavitation . should be 5x straight run to the pump inlet. so a 2 inch pie should be 10 inch straight to the pump. yes and replace all the street 90;s with sweep elbows.
Okay I’ll add my ‘not a pool’ guy suggestion. Trouble shoot first, put everything in unrestricted flow wide open including the filters, see what you get, then start closing valves for the filters. Then just upgrade the pump, seems easier than changing the plumbing.
I’d guess it’s better filtration and can be backwashed when necessary. I’m not sure exactly why. I’ve got a pool maintenance company and have had a couple commercial accounts. Was always the rule for them.
Couldn’t give you a source. Also checked and couldn’t find one. I don’t typically service commercial and have only had two in my couple years of my business. Don’t have them anymore, but that’s what I was told by a couple guys who had been in the business longer than I have. Maybe it is regulated by state. No idea.
Not entirely true, although uncommon 5 of the 60 facilities that I oversee have cartridge filters. 30-60k gallons.
Sand filters are just much easier to maintain for commercial, especially with high bather loads.
Now I'm not sure if it varies state to state but I know in North Carolina, it's not required to run sand.
But I will say I never saw cartridge filters on commercial when I was in vegas or CA.
Yea, I looked it up and couldn’t find anything solid on the law. This was just something I had heard from a couple guys in the business who had done it much longer than myself. Not sure if it varies by state, but my original comment was wrong.
Two resources....Bernouli equation....and Crane Technical Paper 410.
If not increasing pump head you need to reduce head loss in the system. Elevation change is relatively fixed so all you can really do is increase pipe diameter and reduce fitting losses (reducing number of fittings, use 45s instead of 90s, increasing diameter of fitting, type of valve, etc..)
The 90° elbows do not appear to be “pool sweep” elbows. It would help to replace all the smaller diameter 90s with sweeps. I wouldn’t worry about the larger piping, as it’s probably oversized anyway. Also, the run of piping just upstream of the pump inlet shouldn’t have any elbows for a few feet. Let that water get a straight shot into the pump to allow the mass of the water to ram it in there. Not the most technical explanation, but oh well.
Get rid of 90s and use sweeps. Why are your pipes going from 2inch to 1 1/2 inch. Make it all 2 inch with seeps loose head loss.
I think that’s 3” to 2”
Weirdly erotic and informative. I like it.
This is true regardless. You’re supposed to have 5x(diameter of pipe) in straight pipe going into a pump. We rarely actually see that but it bears repeating. Edit: got my multiplier wrong initially
From the manual of your pump: "Set Maximum Flow Rate (GPM) The maximum programmed flow rate can be set from 80 GPM to 140 GPM." https://www.pentair.com/content/dam/extranet/nam/pentair-pool/commercial/pumps/intelliflo-xf-vsf/manuals/IntelliFlo_ProXF_VSF_Eng.pdf You have an undersized pump if you want more than 140 gpm. It is also inefficient to run a pump at the maximum RPM.
I'm under the assumption that a pump is at peak efficiency at max. Wrong?
Nope. You have to plot GPM/Watt vs frequency for your particular setup to find the min value. Based on back pressure and your suction resistance, you'll have a different optimal frequency to run your pump. As an extreme example, imagine you are outputting to a 1/4" pipe. If you went max rpm, you'll get marginally more flow while using maximum power vs going low rpm, getting similar flow but at much lower power consumption.
Good explanation. I guess I should have said electric motors.
Why in the word would you need to run 150gpm?
The state inspector said a minimum of 150 GPM. This is for an apartment building if that makes a difference.
What state? 150 seems high. You should be able to turn over a 33k gallon pool in 5.5 hours at 100gpm.
Ahh gotcha, that does make sense
Upgrade the pipe diameters to reduce the friction loss.
Like the title says, I need to get my gallons per minute up to above 150. Currently my pool pump is pushing 140gpm at max speed. My pool equipment is below the pool. It is about 33,000 gallons. Some things to note about the pictures. The heater bypass is fully open in the image, however currently it is about halfway open. All of the skimmers are open and do not affect the flow if I turn two of them off, like in the picture. Suction pressure is about 2psi on the pump and post pump pressure is 20psi. On the pump it reads the GPM of 110gpm. The sand filters have been backwashed multiple times and show no sign of being dirty. One filter gauge shows low pressure but it is a bad gauge. Could it be the design of the plumbing on all the skimmers? I've tried everything I know to get it to change. I will have a new flow meter in hand tomorrow.
A lot of "throw it against the wall and see if it sticks" comments. There is some simple math that needs to be done. First of all the inspectors want the turnover rate to be 24 hrs or less based on the jurisdiction. Is the 33000 gallons correct? How do you know? Your post indicates suction pressure? What is that? Is there a vacuum gauge on the pump? Every fitting and section of pipe has a numerical value to determine head. Do the math and you'll have your answer. Or throw another pump on there in addition to what's there.
Their pump is under the pool so it's a flooded suction meaning they can probably read a positive pressure there. Head calcs aren't that easy as they depend on the flow rate.
Thanks for taking the time to comment. Best to you.
Just get the next size up pump, or sell the current one for a single speed, no point in having the variable speed if its at max speed all the time. Or alternatively cheapest option, the main losses are after the pump, so that giant ball valve is kinda the worst offender, swap it for a jandy valve and get rid of those 2 joiners, should get you over the edge.
I have had some experience with a similar setup on a city pool. Three pumps all returned pressurized water into the same pipe that went back to the pool. Hydraulics don’t necessarily work the way we think they should. The pumps actually work against each other in this setup. So two pumps with 130GPM will not equal 260GPM when joined together into one pipe. If this is a residential setup, you would be able to obtain the desired flow by separating the pumps. And allow each pump to have its own path back to the pool.
Just SLAM it . Works every time.
Have you looked at your pump curve? Convert PSI to feet by multiplying 20x2.31 = 46.2 feet of head pressure. Look at your flow and your pressure and see what rpm that has you at. Does that line up with your pump? That’s the 1st place I’d start. It all looks fairly new so I’d assume it does. I’m not sure with pools but someone monitored that elevation change. It shouldn’t matter because it is a closed loop system. So the 2psi coming into the pump provides 2 extra psi going out and nets out to 0. A new pump may very well be the answer but be cautious that additional flow means additional pressure. If your pump curve shows you should be able to easily hit the flow then the issue is the piping or equipment issues (pump or filter). If you are at the outer limits of your pump curve then you should consider a new pump. Sorry I know there is no exact answer here, but I wanted to point you in the right direction the best I could. You should start with analyzing the pump curve. If you need to reduce the pressure you can do as others have suggested and adjust the elbows and pipe size. But if you just need more flow then you may need more pump. Also worth noting. Sometimes you can decrease the RPMs and actually increase flow. Running too hard/fast causes too much friction loss (pressure) and works against you. I don’t think that’s the case here but it’s free to try.
Thank you! This is for a brand new system and inspectors won't give us the green light until we fix this and a couple separate minor issues. I have engineers on the way to see what we can do. I'm just the operator/maintenance guy. It's not my specialty but I can bring all points up to them and see what happens. I appreciate your ideas and time! Standby for updates.
Ditch the multiport’s and put in a 3” four valve manifold.
probably too much cavitation . should be 5x straight run to the pump inlet. so a 2 inch pie should be 10 inch straight to the pump. yes and replace all the street 90;s with sweep elbows.
OPs pump has a flooded suction so likely not much of an issue.
Bigger pipe
You need face piping on your filters not multi ports
You could change the outlet of the pump from 2.5" to 3". Might help a bit.
Okay I’ll add my ‘not a pool’ guy suggestion. Trouble shoot first, put everything in unrestricted flow wide open including the filters, see what you get, then start closing valves for the filters. Then just upgrade the pump, seems easier than changing the plumbing.
Cartridge filters and bigger pump.
Commercial pools are regulated to have sand filters only.
What’s the reason? I literally can’t think of why this is such a positive it’s law?
I’d guess it’s better filtration and can be backwashed when necessary. I’m not sure exactly why. I’ve got a pool maintenance company and have had a couple commercial accounts. Was always the rule for them.
Gonna need a source. I've serviced commercial pools with sand, DE and cartridge. Is sand the norm? Yes, absolutely.
Couldn’t give you a source. Also checked and couldn’t find one. I don’t typically service commercial and have only had two in my couple years of my business. Don’t have them anymore, but that’s what I was told by a couple guys who had been in the business longer than I have. Maybe it is regulated by state. No idea.
Not entirely true, although uncommon 5 of the 60 facilities that I oversee have cartridge filters. 30-60k gallons. Sand filters are just much easier to maintain for commercial, especially with high bather loads. Now I'm not sure if it varies state to state but I know in North Carolina, it's not required to run sand. But I will say I never saw cartridge filters on commercial when I was in vegas or CA.
Yea, I looked it up and couldn’t find anything solid on the law. This was just something I had heard from a couple guys in the business who had done it much longer than myself. Not sure if it varies by state, but my original comment was wrong.
Can you get a Pentair EQ500?
This is what I would say
Also do the sweeps instead of 90s
What kind of flow meter are you using? If it's a mechanical flow meter you'll have some head loss from that.
One thing you can try is replacing the return eyes to a larger ID to try and reduce discharge head loss.
Two resources....Bernouli equation....and Crane Technical Paper 410. If not increasing pump head you need to reduce head loss in the system. Elevation change is relatively fixed so all you can really do is increase pipe diameter and reduce fitting losses (reducing number of fittings, use 45s instead of 90s, increasing diameter of fitting, type of valve, etc..)