What's the 3rd valve for?

[cubs6bees]

Hi, bought a house that just happened to have a pool.

28,000 gallon in-ground pool with 2 skimmers

Single-speed 2hp super pump that does not keep prime. I can't find the leak.

One of the 3 suction valves was left closed by the pool company I paid to open the pool. Both skimmers work, although one is sucking at least 50% harder than the other. I thought the main drain was sucking due to some debris sticking there, but haven't confirmed.

What's the 3rd valve for, and should it be open? The pump is 5-10 feet above the pool, so any air leak is too much.

I've thought about closing one of the 2 open valves to isolate and label them, but I don't want to cause more damage. Middle valve handle is already cracked and requires a wrench.

 

[Pool_Medic]

Do you have a main drain?

 

[cubs6bees]

Do you have a main drain?

Yes. Can't tell for sure if it is sucking, but debris continues to get caught on it, which makes me think it is...

 

[cubs6bees]

Do you have a main drain?

Tied a bit of nylon twine to the end of my brush and sank it down there. No suction.

Which leads to a few questions... Why did they leave that valve closed? Can I simply just open it? Could it be causing the priming issue?

 

[Jimrahbe]

C,

The 3 valves are most likely the far skimmer, the near skimmer and the main drain..

The only other option is skimmer, skimmer and vacuum port.. Do you have a vacuum port in the wall of your pool???

Only you can tell what is what..

I suggest that you put your hand under each skimmer basket and get a feel for how much suction there is at the pipe going back to the pump. Then shut off one of the two skimmer valves and check the suction at both skimmers again.. See if one of the skimmer is shut off.. If so you will know what that valve does.. Rinse and repeat for the other two valves..

Keep in mind you will never feel suction at the main drain, unless you cover the whole thing with something.. Most pools don't need a main drain anyway.

If you have a super pump with square O-ring, that would be the first place I'd look for a suction side leak.

The far skimmer will always have the least amount of suction unless you adjust the valves to make up for it.. Open the valve for the far skimmer to 100%, then adjust the valve for the near skimmer, so the the suction you feel under the skimmer basket is about the same for the two of them.. You will have to play with it to get them matched..

Thanks,

Jim R.

 

[cubs6bees]

C,

The 3 valves are most likely the far skimmer, the near skimmer and the main drain..

The only other option is skimmer, skimmer and vacuum port.. Do you have a vacuum port in the wall of your pool???

Only you can tell what is what..

I suggest that you put your hand under each skimmer basket and get a feel for how much suction there is at the pipe going back to the pump. Then shut off one of the two skimmer valves and check the suction at both skimmers again.. See if one of the skimmer is shut off.. If so you will know what that valve does.. Rinse and repeat for the other two valves..

Keep in mind you will never feel suction at the main drain, unless you cover the whole thing with something.. Most pools don't need a main drain anyway.

If you have a super pump with square O-ring, that would be the first place I'd look for a suction side leak.

The far skimmer will always have the least amount of suction unless you adjust the valves to make up for it.. Open the valve for the far skimmer to 100%, then adjust the valve for the near skimmer, so the the suction you feel under the skimmer basket is about the same for the two of them.. You will have to play with it to get them matched..

Thanks,

Jim R.

No vacuum port. They talked me thru using a skim-vac, which I believe would confirm this. 4 return ports are the only other things on the pool wall.

Square o-ring, yes. Can't tell if leaking or not.

If the 3rd valve is for the main drain, what do I do?

 

[Jimrahbe]

C,

Up to you.. You don't need a main drain, so it won't hurt to just leave it off..

If you want, just turn it on and see what happens.

The first thing I would do is get the pool running the way you want first, and then fool with what we suspect is the main drain valve.

I would try to run the pump from just one skimmer at a time and see how well the pump works..

This should tell you if both skimmer lines are ok, or if one of the them is blocked or has some other issue.

Thanks,

Jim R.

 

[cubs6bees]

C,

Up to you.. You don't need a main drain, so it won't hurt to just leave it off..

If you want, just turn it on and see what happens.

The first thing I would do is get the pool running the way you want first, and then fool with what we suspect is the main drain valve.

I would try to run the pump from just one skimmer at a time and see how well the pump works..

This should tell you if both skimmer lines are ok, or if one of the them is blocked or has some other issue.

Thanks,

Jim R.

Thanks. I'll figure out the skimmers. Maybe I can try priming with one closed.

 

[Pool_Medic]

Get all three lines primed then close main drain about 95%. It’s a nice safety net for the pump in case both skimmers go dry.

 

[cubs6bees]

Update: plugs on pump were not installed perfectly. I'm able to prime fairly easily now, but it still won't hold when off. There is at least one leak on the suction side - location unknown, but likely a leak inside the multiport valve that I can hear after turning the pump off, and another drip on the return plumbing after the heater.

The multiport air leak can be heard on the waste line side, and also from inside the drain pipe 20 ft away.

Also, I do have a vacuum port, so that solved the valve question. First valve is the two skimmers, second is main drain, third is vacuum port.