Pool plumbing question - I dont know how it works


New member
Apr 20, 2017
ANaheim, CA
Hi guys,
probably a rather simple question for you guys but I have no clue about this stuff unfortunately.
Got a new house with pool/spa and for some reason the spa doesn't get properly hot. The heater and everything works perfect (really hot exhaust and everything so definitely not the issue) but I think I have to turn one or both valves to just heat the spa and not the entire pool?
Unfortunately I have no idea how this plumbing works.

Could anyone please let me know what the 2 valves do? Do I have to turn one or both to make sure ONLY the spa gets heated?




Well-known member
Apr 6, 2016
It looks to me like you have two suction lines coming from your pool/spa going into your main pump. If I had to take a guess (the way the current picture is) the pipe on the left (the two pipes going into one going to the pump) is plumbed coming from the spa (I may be wrong...I am no expert) and looks like it is turned off (meaning it's only suctioning/pulling water from the pool). My guess is the pipe on the right is the suction line from the pool (drains and/or skimmer). If you were to turn on your heater in the current setup, I'm assuming it would heat your entire pool which could take hours. You need to turn the handle 180 degrees when you want to use the spa only. That way it's only pulling water from the spa. Now on the return side (handle that is to the left and sitting sideways), you would need to turn that handle and have it returning only to the spa. This would be considered "spa mode." The reason it's not heating the spa is because it's all going into the pool. Someone with more experience will chime in, just trying to help out what I can.

Pool Tool

Well-known member
May 15, 2014
Western Chicago Area, IL
Cajun guy seems right, you have two 3-way valves; one on your suction side and one on your return side. When heating the Spa, you'll need to pull suction only from the Spa and return hot water only to the Spa. I would confirm, pipes on left look like the pool and pipes on right look like spa, but just guessing.

With pump on (heater off), move both valve handles to the middle which should suck from/return to both pipes. Then on the higher of the 2 3-way valves turn the handle down which should force all the water up and over the piping and into the spa. You should see level rise and overflow into pool if an option. That will tell which way valve works. Then move back to the middle.

Then, turn the lower of the 2 3-way valves turn the handle to the left. This should take all suction from the tub and you should see the level drop a little.

Once you identify how to suck and return only from the spa, set your valves accordingly, turn on your pump and fire up the heater.