Commercial Pool Pump Configuration Confusion

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chill

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Jan 16, 2012
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My post has some elements that may supersede this particular forum. But, I will put it all out there and hopefully not get flamed on my first post. :lol:

I look after a 120,000 gallon pool in my neighborhood. We have a pool management company that does all maintenance and upkeep. For this upcoming pool season, I am hiring a new pool management company. As a part of that new agreement, I am looking to make some changes to the pool. First off, the pool needs to be re-surfaced. It has been about 10 years and it is in bad need. That decision has been made, and is not the topic of my post. We are going with a DiamondBrite exposed aggregate surface of some type.

We currently have four sand filters and four 2hp pumps currently. Chlorination is via a stick chlorinator feeder. We switched from liquid chlorine two years ago when the last pool company suggested that the liquid chlorine was dangerous and less efficient. I have found that is not necessarily true, but like most things with pools, everyone has a different opinion. Every year, I replace at least one pump, sometimes two. I have gotten mixed advice on why that is happening. My best guess is that I am getting failures because the plumbing configuration is causing a situation where the pumps are fighting each other. Some pumps win out and the ones that don't are getting air in them, losing prime and are more frequently prone to death. Strictly a theory, but I have seen the lost prime problem happen with my own eyes.

So, as we head in to this season, I am looking at doing one of three things:

1) Nothing - Keep the system in the same configuration. Replace pumps as necessary.
2) Keep the four pump, four filter system, but re-evaluate the plumbing to make it more efficient.
3) Switch to a one pump system (i assume keeping the four filters).
4) Switch to a salt-generator system and replace the necessary plumbing.

So, my dilemma is which option to choose. I have looked through this forum and have found good, yet conflicting information. Is there anyone skilled in the art of pool pump configuration that can give me some advice and guidance. I am looking for something to help me decide against the two vendors I am looking at.

One of the vendors is against salt and says I will have problems after two years. He also indicated that I should really switch back to liquid chlorine instead of the stick feeder. The other vendor is pro-salt and indicates that with periodic cleaning, a good salt system will last a long time. The pro-salt guy is not pushing it as much as I am wanting it, but will be proposing some pump configuration changes shortly.

Any advice from the forum would be greatly appreciate.
 
Hey, chill,

welcome to the forum! :lol: You will get a lot of advice here (mostly good) but you won't get flamed. We pride ourselves on our good manners and, generally, our pool knowledge although a setup your size is certainly out of my area of expertise.

You'll get positive feedback here on the SWG options and liquid chlorine. Probably not too much good to say about the stick chlorinator although it can certainly be succesful if managed properly.

I'll let some others chime in who can probably offer better advice for pools that size.
 
Do you happen to have a schematic of the plumbing layout or perhaps create a simple one?

First, I would try to figure out why the pumps are failing. Has anyone taken the pumps apart to determine exactly what component in the pump is failing?

Also, I think option #3 is out since you couldn't generate enough flow rate to turn the pool over enough times per day. Most areas there is a maximum turnover time of 6 hours for commercial pools which means you would need 333 GPM. With four pumps at 85 GPM each, that is pretty easy to achieve, with one it is impossible.
 
Thats interesting about the single pump. I have had a couple of folks say that a single pump (~10hp) could turn the water if all four filters were lined up in a row with limited turns in the piping. I will take a picture tomorrow morning and post it.

The problem we have ben having with the pumps is that the motors burn out, or the bearings go bad. When it happens, you can hear them running from 100 yards away. At one point we were having the motors rebuilt and that did okay, but it was never a long-term fix - but then again - the new motors don't seem to be a long-term fix either.

I will post the picture tomorrow. I might even take a video and put it on youtube and provide a link.
 
The more complete the plumbing schematic, the better. Please include pipe sizes, as far as you know them.

Is the equipment indoors or out? Is the pool an indoor or outdoor facility?

Where are you located?

Some pictures of the equipment and pool would be greatly beneficial. Maybe even a You Tube video! :-D

Scott
 
Here are a batch of pictures that show the pump configuration. I have labeled all of the pumps and filters in each picture. I could not get up high enough to get one shot with all four pumps and all four filters, so hopefully the collection of images will give you all a good enough idea of what we have. Let me know if there is any other information that may be helpful to you all. Because of file size limits, I will send 5 posts each with one of the pictures.

[attachment=0:3p01kej8]lfhoa_pump_pic1.jpg[/attachment:3p01kej8]
 

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My best guess is that I am getting failures because the plumbing configuration is causing a situation where the pumps are fighting each other
Click to expand...
I think you may well be right.

Again, that pool volume is beyond my area of experience but it looks like they were really fighting some space constraints and ended up with a spaghetti mess. My natural tendency would be to start over.
 
The suction side manifold should NOT be reduced as pumps are attached. Its main should be the same size all the way. This ensures all pumps get to work equally. Each should be valved though and they aren't.

There should NEVER be a check valve on the suction side of a pump.

There is no SVRS system.

The previous two points are serious entrapment risks!!!!!

What size are those pipe mains, suction and return. The return side may be too small.


Scott
 
chill said:
Thats interesting about the single pump. I have had a couple of folks say that a single pump (~10hp) could turn the water if all four filters were lined up in a row with limited turns in the piping. I will take a picture tomorrow morning and post it.
Click to expand...
What I meant was that it was impossible to run the plumbing with a single conventional pool pump. You might be able to find a 10 HP pump from the water distribution industry but as far as I know, the pool equipment manufactures don't make one that big. If you did go that route, the filters would need to be plumbed in parallel and not series. But since you have two suction lines, at a minimum, I would use at least two pumps, one on each of the suction lines. But really if you just split the two suction lines in two, you have four parallel lines that can then feed the four pumps. If each of the splits and suctions is equal, you can ensure equal draw from each pump.



chill said:
The problem we have ben having with the pumps is that the motors burn out, or the bearings go bad. When it happens, you can hear them running from 100 yards away. At one point we were having the motors rebuilt and that did okay, but it was never a long-term fix - but then again - the new motors don't seem to be a long-term fix either.
Click to expand...
Both the windings burning out and the bearings failing prematurely is an indication that the pumps are running far off the best efficiency point close to run out. Are only some of the pumps having issues or have you had to replace all of them at least once? Also, what has the filter pressure been like on all four filters?
 
Pentair has commercial pumps from 3 to 50 HP. Connecting the suction side to the existing skimmer and drain lines is not hard. Connecting a single pump to the 4 filters is harder but doable. Using a single pump is not ideal since a failure there will down the pool.

A single pump design would require a variable speed drive.

My gut tells me the return plumbing is too small and is generating too much head. The suction side manifold isn't helping either.

The lack of an SVRS and the check valves are also needs that MUST be addressed. A US building inspector would be right if he shut the facility down for this, even if current VGB drain standards are met . Is there an emergency shutoff that kills all the pumps at once outside the equipment room? If not, then that would be another safety violation.

Scott
 
In picture 4: What is that pipe with the round blue valve (second from the top) for? Is it a fill line? What's the pipe at the top of that picture?

How many return lines are there? Do all 4 pumps feed into a common pipe to the returns?

Also, it looks like on pump 3 there are lines splitting off between the pump and the filter - where do those go to? Any reason these are before the filters and not after them?
 
You guys are posting some excellent questions. I can't answer most of them, unfortunately, because I am not a pool guy. The two inlet pipes from the Skimmers and Main Drain (Marked on the pipe in picture 4) are 10 inches in diameter. The other pipes pictured are 3 inch. I assume the other two are returns.

There is no emergency shutoff. I agree that even though we have VGB complaint hardware, we really need to have this. I will have it included in any quote we get for re-working our pump room.

When I get home tonight, I will try to visually figure out which line is for what and try to better answer some of the excellent questions you are asking.

I will pose this question....If we were to switch to Salt, would it make sense to re-plumb the entire system, though I guess that there is a chance it is required anyway.
 
After taking some time and looking at it closely, it doesn't look like a huge problem to replumb that setup correctly. Pictures can be deceiving but the suctions look like 8" and the return looks like 4". As Scott said, the suction side should not be reduced until the last pump and I would leave the return side full size all the way to the last filter as well. There are a lot more fittings in that plumbing than there need to be.

The backwash line can be the same size to all the filters because you're not going to be backwashing more than one filter at a time.
 
Do they need check valves between the filters and the return manifold? If they are sharing a backflush line then they should also have check valves on those too after the sight glasses right?

Where would a salt system be plumbed in? I'd guess several cells too?
 

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