How to Properly Run Plumbing Through Heat Exchanger?

[xrabbi]

Our PB completed the plumbing setup before the inline heat exchanger was available for installation. Now that we're installing, I'm not quite sure the plumbing is set up quite right. Would really appreciate any advise/observations on the setup and how it really should be arranged.

As you can see in first picture below, all pump equipment is in the garage, 10 ft below water line. Beginning in left corner, pool water comes down into pump, through filter, then through the grey heat exchanger section, and then back up and around through SWG before heading back to pool. In the way the plumbing is designed/arranged, is the idea that the water is supposed to come from filter, some (but not all) of it is supposed to go up the first grey column and through the heat exchanger and then back down the other grey leg to join with the water that is going straight along floor from filter to the return line? As you can see, there are Jandy valves on each leg, plus a check valve on the righ-hand down pipe below the heat exchanger. I would have thought the purpose of the check valve is to prevent backflow into the heat exchanger, though it now seems to be installed the opposite way (see picture at bottom). If that is all right, what is the purpose of the grey crossbar midway up the wall between the two Jandy valves. To create further bypass? What is the right position setting for each of the Jandy valves? Sorry for the noob question and appreciate the group's wisdom! Thank you.

 

[mas985]

Water will not flow through the heat exchanger because the path of least resistance is through the white PVC bypass. The valves should have been places where the white tees are so that could be closed off. If you cut and cap that white connector pipe (both ends), the the water will flow through the heat exchanger when the Jandy valves are set to close off the cross pipe.

 

[xrabbi]

Thanks. I suppose I can also just put a new Jandy valve in middle of the while PVC bypass at bottom. When closed, water will be forced up through the heating loop (assuming the higher existing Jandy valves are set to close off the grey cross pipe, which I guess has no purpose). Would that be better since in theory I could experiment with opening the new valve in the white bottom point just enough to force flow upwards but not enough to restrict overall flow?

 

[Dirk]

If I can consider the exchanger as if it were my solar panels, neither of the suggested fixes would be best. Yes, the white section is negating the proper flow, but if you just cap it off, or put a valve in the middle of it, then it would be possible to set the valves such that it would completely block the flow from the pump. Which is fine if you never forget about that, and never let anyone else near the valves, but not ideal in that you've got a potential disaster lurking. Especially because that plumbing is below the surface of the pool!

The solution is to put a three-way in place of the tee on the left (literally or functionally) and remove the other three-way all together (so there is only one, total). That remaining three-way can be used to send all water to the exchanger, no water to the exchanger, or anywhere in between. The check valve remains, the grey bypass goes away. Then there can be no accidental blockage, because that one three-way can only send water one way or the other, not stop the flow. The check valve keeps water from going the wrong way. Less is more!

 

[Dirk]

Just noticed, that check valve is facing the wrong way! So unless I'm completely missing something, that, too, would have to be corrected. The way it is now, water can only flow through the exchanger right to left, if at all based on valve settings. Weird.

 

[xrabbi]

Yes, sharp eyes. I think PB just had his folks throw stuff together without too much thought since they did not have the exchanger on hand and could not test. A single 3-way makes sense to me, however, assuming there is no plumbing/pressure reason for the multiple bypasses.

 

[Dirk]

The second (or third) three-way creates a potential pressure problem, doesn't solve for it. The danger is if, with pump off, Captain Kirk sneaks into your garage and redirects the plasma flow of the Enterprises' warp reactor, then transports out without you realizing it. Next day, when the pump fires up at full-on priming speed, it could blow apart the weakest fitting, or your filter, and some or all of your pool would drain into your garage. It has to be kid proof, uh, Kirk proof.

If there is a consideration about how much flow moves through the exchanger, the three-way can be configured to limit it's "swing" such that it can't be moved 100% to exchanger, so that some amount of flow always bypasses directly to the pool. That should cover whatever the plumber thought he was accomplishing with the other bypasses.

 

[xrabbi]

Thank you. Can either of the existing Jandy valves be reused or do I need to just cut them out and buy a new one?

 

[Dirk]

Sure, reuse. Just cut them out leaving a good length of PVC on all three ports, then glue them back into position using three couplers. EZPZ.

 

[xrabbi]

Ok, will try and report back. There will be a lot of water on the garage floor today, I'm afraid, once we start cutting the pipe ...

 

[markayash]

Would have been nice if they had installed cut off valves where it comes through the wall

 

[xrabbi]

Thanks all! A further noob question -- looking at the second picture in my iniital post above, can the left bottom tee (which is lying flush on the concrete floor) be replaced with a Jandy valve that has a rounded edge that protrudes so will not be able to be easily installed flush with floor and the adjacent plumbing?

 

[Dirk]

Mark - I think there are cut off valves. One you can't see in the pic, the other is up top?

xrabbi - You could take this opportunity to plumb in a hose bib at the lowest point, as a drain for "next time." I have that on my solar pipes to help me clear them in the winter. You'd use a 2x2x2 tee, with a reducer down to the threads of the bib, like this:



You could then close the two isolation valves and drain everything out the bib using a hose to direct water out of the garage.

 

[Dirk]

Thanks all! A further noob question -- looking at the second picture in my iniital post above, can the left bottom tee (which is lying flush on the concrete floor) be replaced with a Jandy valve that has a rounded edge that protrudes so will not be able to be easily installed flush with floor and the adjacent plumbing?

I don't see why the Jandy has to be on the floor. You could replace the tee with a 90 and bring all that up a ways. As long as you maintain the function, it doesn't matter where the valve is. There's a way to do this without even cutting out the left three-way. Hang on, I'll draw it for you...

 

[Dirk]

Like this. This is assuming the flow through the exchanger can go from left to right. There are any number of ways to reconfigure this, to further clean things up, as long as the water pathways work the same.

 

[Dirk]

The check is too close to the elbow to reuse it with the same size pipe. There is a work-around for that, to be able to reuse it, but there are two other possibilities. You might be able to flip the guts around without having to cut anything, just unscrew the clear cover and see if you can flip just the innards. I'm not sure it works that way, but try that first. If not, I would ask the plumber to spring for a new one, since it was his mistake (a very ridiculous mistake at that). It's the least he can do for this mess he left you.

 

[mas985]

If it were me, I would still do as I suggested above and if you are concerned about blocking the flow, the valves have stops on them that will prevent the main path from being closed. On the second valve on the right, you can just remove the handle and it will act as a tee. It would save quite a bit of rework. Plus the second valve is nice to have so you can isolate the heat exchanger.

 

[Dirk]

When you got all that working, you might have a go at all those dangling wires. Tidy all that up with zip ties for a professional look!

Mark's post came in while I was typing. I cannot fault his logic. It is technically less fool proof, but not likely practically so. I described how I would redo the plumbing, not with an eye for the easiest way, because I never do things the easiest way!!

 

[xrabbi]

You guys are amazing and incredibly helfpul, thank you! I was able to flip the check by unscrewing the top without cutting. I was generally thinking that Dirk's first idea of moving the left valve down to the bottom white PVC bypass pipe would be easier for me since it leave all the remaining white plumbing in place and then either remove or close off the grey crosspipe (also leaving the right Jandy in place as a fixed tee as you suggest). I also like the idea of having a long vertical leading into the heat exchanger since I can then mount the flow switch and acquastat there (they are now between pump and filter as you can see in picture, which seems suboptimal because that doesn't guarantee flow to the heat exchanger).

 

[Dirk]

Be sure you think that through. If you put either of those gizmos on the wrong side of the three-way, that could negate what they are doing, as the flow to the exchanger will sometimes be shut down by the three-way, right? For my solar system, which is controlled by my automation and an actuator on my three-way, the temp sensor has to be before the three-way for the system to be able to monitor water temp all the time, and control the three-way accordingly. Not sure what the flow switch and acquastat are doing for you, but don't isolate them on the wrong side of the three way unless OK to do so.

Glad to know the check was an easy fix. One down...