What is this 3rd pipe?

[Sinjun]

Hello all!
Bought a home and it came with a large in ground pool. Mostly got it under control but I have a question.
Shown on this photo you can see 3 pipes with valves coming into the pool pump.
The one on the left marked D is from the Drain, the next marked S is the Skimmer, but the 3rd is marked R (RLL) - its valve has never been opened by me.
What could that pipe be?! All 3 pipes exit the pump house and go directly underground.
The pool itself has 1 drain, 1 skimmer, and 2 return jets.
The return line can be seen on the far right of the photo.
I have no idea what the 3rd pipe is marked R going into the pump.
Any ideas?

 

[reggiehammond]

Perhaps a vacuum port somewhere in pool?
It would look like a pool return fitting, but you'd be able to attached a vacuum hose to it.

 

[1poolman1]

Hello all!
Bought a home and it came with a large in ground pool. Mostly got it under control but I have a question.
Shown on this photo you can see 3 pipes with valves coming into the pool pump.
The one on the left marked D is from the Drain, the next marked S is the Skimmer, but the 3rd is marked R (RLL) - its valve has never been opened by me.
What could that pipe be?! All 3 pipes exit the pump house and go directly underground.
The pool itself has 1 drain, 1 skimmer, and 2 return jets.
The return line can be seen on the far right of the photo.
I have no idea what the 3rd pipe is marked R going into the pump.
Any ideas?

Close D & S, open R, turn on pump, and see what happens. That's the way to find out.

 

[Sinjun]

Perhaps a vacuum port somewhere in pool?
It would look like a pool return fitting, but you'd be able to attached a vacuum hose to it.

There are only 4 openings in the pool. 2 are definitely return lines, 1 is the skimmer, and the 4th is drain at bottom of pool.

 

[Sinjun]

Close D & S, open R, turn on pump, and see what happens. That's the way to find out.

I’ll give that a shot. What I’m curious about is that it is on the suction side of the pump and there is only a pool drain and skimmer, what could it possibly be sucking from?!

 

[Rancho Cost-a-Lotta]

Are you sure you don't have an accessory port for a vacuum? The "R" could be for robot.

Edit... feel free to ignore this post. I see Reggie has already asked about a vacuum port.

 

[Bluedart]

I have three valves to pump; skimmers, drain and well. That is how I fill my pool and lower water table when I drain it to paint it. It’s an old well point from when they first built pool . I would try to turn it on with the filter to waste and see if it can prime and pump water. If it does test water for chlorine and see if it is pool water or well water.


I would not use it unless you have a cement pool since lowering water table could cause issue with other pools.