Pool plumbing anatomy help needed

[JohnGn]

I have a few questions about the plumbing of my pool. I inherited the pool when I bought the house, and the previous owners are not knowledgeable.

See the drawing of my theory on how this pool is plumbed, but I am absolutely NOT certain of of this.

IG vinyl 16x32 pool. I have a sand filter, two return jets, a main drain and one skimmer. Just to the pool side of the inlet to the pump is a ball valve. Inside the skimmer are two holes in the bottom. I *believe* that the hole closest to the pool is the line feeding the pump (suction side, since that's pretty obvious when the pump is running), and the hole furthest from the pool is the inlet from the main drain. This is the part that I'm not sure of.

Attached to the bottom of the skimmer is a "diverter" assembly that has both a valve and a flap that can swing into position to block of the flow of water from the water line of the pool into the suction side of the skimmer entirely.

The way the pool seems to work best is to turn the diverter valve inside the assembly in the skimmer to a 45 degree angle, and move the top flap so it is about halfway covering the top port. In theory, that means I am pulling water equally from the main drain and the water line into the skimmer.

The questions I have are:

1. Why does the pump get completely starved of water when I turn the valve in the diverter so it is horizontal and close off the top flap? Based on my understanding, this position of the diverter should be sucking 100% of the water from the main drain, but the pump is almost immediately starved and no water comes out of the return jets.
2. Why does the pump get completely starved of water when I turn the valve so it is perpendicular and open the top flap completely? This is how I should be able to generate maximum suction for my vac hose, for example. It simply does not work. Is there something I am missing in order to generate maximum suction for my vac hose?
3. How do I winterize the pool with this type of setup? I'm specifically referring to the main drain plumbing when asking this. Do I blow air into the "main drain" side of the skimmer until air bubbles up from the main drain at which time I can plug the port and create an "air lock"? Water line would be below the skimmer during this operation.

Thanks for any advice or guidance.

 

[Jimrahbe]

John,

Show us some pics of your Equipment pad.. It will help us verify your drawings..

Thanks,

Jim R.

 

[Jimrahbe]

John,

When a skimmer has two holes, normally the hole closest to the water goes to the main drain. The other hole goes to the pump.

I am not sure I fully understand how your diverter works, but obviously, if turning it to any position shuts off the water to the pump you don't want to do that.. Not sure if the problems is with the diverter or how you think the diverter works???

Your first drawing makes sense other than which pipe "normally" goes to the main drain.

Main drains can cause leaks and because of this they are often plugged.. It could be your main drain is plugged. Main drains are almost never needed. Thousands and thousands of pools run just fine without an operating main drain.

What happens when your vac is not connected. If you leave your vac connected the skimmer will never work.

Let's see what some of our other members have to say.

Thanks,

Jim R.

 

[JohnGn]

Thanks for the reply, Jim. The hole closest to the pool definitely seems to go to the pump because it sure seems to be pulling a ton of suction. That said, there's no telling how the installers plumbed this pool. That's why the behavior is so odd, based on the documentation for things like the Hayward diverter.

However, if I am wrong and the main drain is the hole closest to the pool and the pump is fed by the hole furthest from the pool, then it would make perfect sense IF the diverter assembly happens to be installed backwards. When I first got tutored in how the pool works by a pool pro, the diverter was installed exactly as shown in the photo above, with the hole on the top (with the swinging flap) mounted closest to the pool. He told me that "normal" operation is with the valve at a 45 deg angle and the flap covering about half of the top port. In that orientation, it wouldn't matter if the diverter is installed backwards!

The manual suction-side vac I've tried to use simply has a skimmer adapter disk that fits over the entire skimmer port and the vac hose connects to that. In theory, I would want to set the diverter to max suction for greatest vac efficiency. But this has never worked very well. It generates modest suction at best. The only way I've been able to get a functional suction is when I insert the vac hose directly into the fully open port on the top of the diverter assembly and leave the valve set to a 45 degree angle so the pump doesn't cavitate. I only use the manual vac when the pool is very dirty due to pollen or algae. In normal times, I use my new Warrior SE vac bot.

I will check tomorrow to see if rotating the diverter assembly 180deg helps and update if needed. Thanks.

 

[HermanTX]

If as you say the diverter valve is installed backwards, it makes sense that at 45degrees it works regardless of how it sits on the 2 holes. Can you remove the diverter valve completely? It appears to have 2 hold down screws but not sure they can be removed. If you can, you can simply determine which has the suction with a tennis ball placed on the hole. Best if you have 2 people so you do not cavitate the pump. Once you determine which hole is the line to the pump then set up the diverter valve to work as it is designed.

 

[Dirk]

So that's what they look like! I have the same plumbing, but I never got my diverter! If you can take it off, do so. Don't stick your hand in there with the pump running. Drop a small leaf or two in the skimmer (without basket) and see which port sucks them in. That'll confirm that. Then figure out which way the diverter is supposed to go. Is it marked somehow to show you which end goes over which port? If not, see if you can google some installation instructions. Then install it correctly.

Herman's post came in while I was typing. We're basically saying the same thing. But don't use a tennis ball and deadhead your pump, even with two people. A leaf or two is harmless and will get trapped in the pump basket.

If the diverter and main drain don't work after that, then take the diverter off, basket out, and with pump off, seal a hose to the main drain port in the skimmer as best you can (use a small rag) and pump water down it. See if you can spot water coming out of the main drain. Be prepared for a bunch of crud. DO NOT jam the hose down there. Just the tip. Don't mess with your main drain pipe. If you break it or a fitting, that would be a disaster.

If there's no crud, and you're confident the main drain is plugged up, then you could work on that, or just leave it alone. If your pool has been circulating fine without it, then there's no real reason to restore it. As Jim points out, you don't really need a main drain. I sealed mine off, pool works fine. I had mine plastered over, but because I never got a diverter, the main drain never worked in the first place.

Then ditch the diverter in a drawer and connect your vac to the pump port in your skimmer and you should be able to suck the plaster off the walls if you want to!

 

[Dirk]

Thinking about this more... and based on no actual experience with the thing, mind you: if the pump starves in both 100% skimmer and 100% main drain positions, then I'm gonna bet that both the thing is in backwards AND the main drain is clogged. I'll put a fiver on that...

You get flow at 45°, but since the main is clogged, you only get 50% flow, which would explain why the vac is weak. I'll put another fiver on that!

 

[JohnGn]

Thanks for the help!

Yes, the diverter assembly comes off. We have to take it off to winterize the pool using a gizzmo. So I will be doing the test tomorrow with a leaf.

I will say this: I am about 99.9% sure the port nearest the pool is the line to the pump because that bad boy almost took my finger off once. But I'll double check.

As far as the main drain being clogged, it would not surprise me one bit. I'll try the garden hose trick and see what emerges from the drain, although it is covered with the plastic piece with all the little holes in it. I have noticed that things like leaves and hair do collect there from time to time in the summer, and I just use my pool brush to pull the stuff off the cover. So, there may in fact be at least *some* water moving through the pipe up to the skimmer. Maybe it's partially clogged, which would also explain why I can't throw the diverter into full "sweep" position (which is what the label on the diverter calls it when set to pull 100% from the main drain).

What is still unexplained is why I can't set the diverter so that I get max suction by cutting off the main drain completely, clogged or not. When I try to do that with my standard manual pool vac (with water totally filled inside the flex hose before attempting so it's not sucking air), the vac suction goes to near zero and the pump starts to growl and gets starved. It just makes no sense.

I'll try running things with the diverter removed and see what kind of skimming action I get plus check the returns to see if they are running normally. I seem to recall opening up the pool for the first time after buying the house and running the pump without the diverter and the returns were producing a weak jet. Yet when I put the diverter in and put it in the 45deg position with the little top flap about halfway, the flow into the skimmer INCREASED dramatically AND the output pressure from the jets increased a lot as well, to what I consider a normal force. As I said, the pool's circulatory system seems to be happiest with that goofy thing installed at the settings that make no sense.

 

[Dirk]

What is still unexplained is why I can't set the diverter so that I get max suction by cutting off the main drain completely, clogged or not. When I try to do that with my standard manual pool vac (with water totally filled inside the flex hose before attempting so it's not sucking air), the vac suction goes to near zero and the pump starts to growl and gets starved. It just makes no sense.

It does, though, if the diverter is on backwards (I had to think this through myself, so it took me a while)!

If the diverter was on correctly, in one position the pump would pull from the drain, in the other position, the pump would pull from the skimmer. When pulling from the drain, the skimmer is completely isolated (blocked) from the pump. And when pulling from the skimmer, the pump is isolated from the drain.

Now flip the diverter backwards. In drain mode, the pump would still be able to pull from the drain. But because the pump starves, that indicates the drain is clogged (or partially clogged). In skimmer mode (remember, normally this would block the drain), because it's backwards, the skimmer is now connected to the drain (doing nothing) and the pump is being blocked! That's why you get no suction and why the pump complains. The pump pipe is blocked (because the diverter "thinks" that's the drain pipe) and the skimmer is connected to the drain, not the pump!

That's why I think you have two issues, a clogged drain and a backwards diverter. If the diverter is on the right way and the drain is clogged, you'd still get a complaining pump in drain mode, but you'd get plenty of suction in skimmer mode.

It sort'a works in half-n-half mode because normally that would be drawing water from both skimmer and drain, and that would work whether the diverter was on correctly or backwards. But because you also have a clogged drain, the half-n-half mode is only drawing water from the skimmer, but blocked 50% by the diverter's flap, so you get 50% flow. Which, apparently, isn't enough to drive your vac.

Did I explain that any better? Like I said, that's my guess...

 

[HermanTX]

But don't use a tennis ball and deadhead your pump, even with two people.

Let me explain my reasoning. I felt the OP has a well enough understanding of pump dynamics so the risk is minimal if you watch the pump. Second though is it helps clear any debris in the suction line from the skimmer to the pump. If a larger piece of debris is stuck that too can be adding to the low suction issue regardless of what position the diverter valve is in. It won't clean the main valve line because of the set up but goal was to ensure the skimmer line is full open as well. I have done this on mine and have been successful in not damaging the pump nor getting the tennis ball stuck! It is simply an option. Thanks for listening.

 

[JohnGn]

Thanks, Dirk. I think you and I are in complete agreement. What I meant by how it is still a mystery is that based on my experience seeing the suction taking place at the port closest to the pool (which goes to the pump), then that would mean the diverter *is* currently installed correctly, and I should get max suction when shutting off the drain side, but I don't. In fact, it ends up starving the pump, too. Not as "instantly" as when I switch to full drain mode (indicating a clog or severely reduced flow somewhere in that line), but it still starves the pump and the vac suction is very poor. But when I switch it to 45deg, I get better (functionally OK) suction with the vac.

I'll be out there testing things once the coffee kicks in this morning.

 

[Dirk]

Let me explain my reasoning. I felt the OP has a well enough understanding of pump dynamics so the risk is minimal if you watch the pump. Second though is it helps clear any debris in the suction line from the skimmer to the pump. If a larger piece of debris is stuck that too can be adding to the low suction issue regardless of what position the diverter valve is in. It won't clean the main valve line because of the set up but goal was to ensure the skimmer line is full open as well. I have done this on mine and have been successful in not damaging the pump nor getting the tennis ball stuck! It is simply an option. Thanks for listening.

Interesting that that MO has worked. I think it would just as likely further jam up something in there as set it loose. But more importantly, I wouldn't take the chance of messing with underground/under-concrete plumbing in any way that might cause damage. Especially since there are better, less riskier ways to clear a clog. Repairing a cracked pipe or fitting under a pool or deck could be five figures. Too risky for me.

 

[Dirk]

Thanks, Dirk. I think you and I are in complete agreement. What I meant by how it is still a mystery is that based on my experience seeing the suction taking place at the port closest to the pool (which goes to the pump), then that would mean the diverter *is* currently installed correctly, and I should get max suction when shutting off the drain side, but I don't. In fact, it ends up starving the pump, too. Not as "instantly" as when I switch to full drain mode (indicating a clog or severely reduced flow somewhere in that line), but it still starves the pump and the vac suction is very poor. But when I switch it to 45deg, I get better (functionally OK) suction with the vac.

I'll be out there testing things once the coffee kicks in this morning.

I think my theory explains the symptoms, but that doesn't mean there isn't some other explanation. Looking forward to you solving the mystery.

 

[JohnGn]

Well, to update things a bit, it turns out that my initial drawing above is INCORRECT, and Jim R. nailed it when he said that the port closest to the pool connects to the main drain and the port furthest from the pool goes to the pump.

This, of course, would then make total sense. I was merely operating the diverter incorrectly, based on incorrect assumptions. It was also installed backwards.

The good news is that my main drain is not clogged at all. In case that matters, which apparently it doesn't too much.

I have not tried running my manual vac, and probably won't until perhaps opening the pool in the spring.

Thank you all for your input and remote diagnoses. Love this forum.

 

[Dirk]

Glad you figured it out! We loves a happy ending!!