How much of a crime is it to put a 3-way valve on the inlet of a pump?

Ok, so in adding in the main drains I am considering adding the 3-way valve to balance the drains and the skimmer to the equipment pad, but the situation I have is if I do that I end up with the outlet sitting at the inlet of the pump.

When I say this, I mean there is a 2 to 1.5" reducer and a male adapter directly off the T portion of the valve into the pump inlet and the skimmer and main drain connections are connected to the run, so I would have the "dreaded" rams horn configuration where the flows collide at the inlet.

The way I have it configured right now, without the main drain, is the riser comes up through a ball valve, to a 90 degree elbow, through a union and into the pump. It has about 9 inches of straight flow into the pump.

I do have an option of plumbing the main drains out at the pool and putting the 3-way valve out there to control flow to the pump inlet. If I did that I would not have to mess with the plumbing at the pad and I would end up with an extra line for anything else in the future.

But, if it isn't such a crime to put the valve on the inlet of the pump, then that would be my "preferred" way of plumbing it for now. Everything is 2" PVC plumbing for reference.

I also did come up with a design that puts the run of the valve at the pump inlet and will still allow for a 9" straight shot into the pump from the skimmer, and the inlet from the main drains would intersect into the side of that flow when they are enabled.

The big issue with that design is I would basically be hard plumbing the ball valves to the Jandy never-lube. That, to me, seems like a huge issue since I am sure at some point the ball valves will fail and then I am forced replacing the entire assembly. Now, if I went with a set of Jandy never-lube 2-way valves I guess that is not a problem and would afford for me being able to replace just the internals if they fail. That just means more expense.

Why keep the ball valves?

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Originally Posted by BigDave

Why keep the ball valves?

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The ball valves are there so that I can isolate the pad from the pool for maintenance and winterization. I also have redundant valves out at the pool for the same purpose/reason.

Basically for winterizing I should be able to drain teh water below the returns, shut off the pool plumbing at the pool, disconnect all the unions, blow out the lines, close the ball valves at the pool and the equipment pad, reconnect the unions at the pool, disconnect the equipment at the pad and remove the equipment for the winter. No water in the lines and them close off at both ends.

For service, depending on where it is, it is just a simple matter of isolating off everything else via the ball valves and being able to disconnect and remove what is needed.

Or, are you suggesting I don't even worry about a 3-way valve at the pump, simply plumb in the ball valves like I have, tee them together and just use the ball valves to control the flow?

I thought about that, but was thinking that 3-way valves die much more often than a Jandy Neverlube would and even in a "dead valve" situation with a ball valve I would have the Jandy as a "master control" valve that could block off both feeds with simple reclocking of the valve in the body. ie, if I had a ball valve fail I could still use the Jandy valve to block off both inlets.

I don't think you can safely leave a ball valve closed for the winter - there's water trapped in the valve body when it's fully closed or open.
You certainly could build it with the two ball valves and a Tee and other parts. I thought you were introducing the three-way to make one flow straight through with the other entering from the side. Are talking about a 3-way valve other than a Neverlube?

Actually if the valve is vertical there is no water trapped in it. Especially if you leave it half open for a day before closing it off in that orientation.

All of my ball valves are vertical except for the combo valve used to shut off outlet flow from the heater. All the rest are plumbed vertical to make sure that all water is out of them when I want them dry.

I also am only talking Jandy Neverlube 3-way valves. No sense wasting 2/3 the cost on lower-end/no-name valves for the 3-way ones.

All the rest of the ball valves are Nibco brand valves rated for pool use. Interference fit ball closure with no seals. The only seals for those valves are in the stems. Unless you get a ton of dirt in them to gum them up, they should operate and seal pretty well. On the return side of things I have little concern, it is the suction side that would get all teh gunk trapped in them, if at all. And being vertical it should help them even in that regard compared to ones laying horizontally.

Well, I got the valve installed on the inlet... I had to use the "ram-horn" installation with both the skimmer and main drains coming together at the inlet...

But, I did get the valve 9 inches away from the pump, so I feel better about it being situated there... I also have the main drains on the side that had to go up and around to the valve vs just up and over, so hopefully it is balanced better...

I'll go take a pic and post up how it turned out...

Pic:

http://www.darklogic.net/P1020558.JPG

No more than any other shut-off valve there. I keep a shutoff in the place to make emptying the pump basket a snap!