Should I install a valve before this pump (picture)?

[TwinsPool]

Yes, I am doing all the pumping at 100% speed (3450 rpm).

Like you, I have decided that I've done enough diagnostic testing. I am going to replumb everything plastic that is visible above concrete to the pump (I will need to leave the copper pipe there). I am planning a new transition coupling at the copper pipe and new PVC and possibly see if I can add a good check valve on the way to the pump. The union at the pump will also be replaced as long as I am sure what I buy will fit well onto the pump.

I do think the underground pipe is all copper. The pool was installed by an earlier house owner in 1977 (according to city permit records). Also, the pipes leaving the skimmer are also metal (probably copper, but they are below the skimmer, and by feel they are definitely metal of some sort).

I am pretty sure that the transition fitting between the copper pipe and PVC is this type of so-called "compression" fitting shown below. From the image (which came from a pool supply website) it looks like a "SharkBite"-type of O-ring connection to the copper pipe. That's not ideal, but it is what it is, and I will just replace it whenever it starts leaking.

The description for this item is: 21098-150-000 Copper to PVC Adapter 1.5in. to 2 in. / 1.5in. PVC

Please let me know if you think I'm way off or anything (or if it all looks okay).

Thanks for your help Ol_whistle and everyone else. It really helps to have people to discuss these problems with.

 

[TwinsPool]

And for the check valve, and to save space, I tentatively plan to use this Jandy 90-degree check valve. Any reason not to do that?
That is, would this addition be seen as an overall positive or a negative?

 

[HermanTX]

My questions now are... Should I just smear silicone sealant (or something else) over the problem area where leak is, or should I rebuild this junction and perhaps the whole path to the pump?
If rebuild, does anyone have an idea what sort of junction this actually is, and where I would get parts for it?

Have you tried to back off collar of that connection from copper to PVC? Normally a collar such as that pulls 2 pieced together to form the seal. The collar supplies the compressive force, it does not seal any thing. There should be a rubber seal between the 2 mating parts.

What you have found appears to be correct. I think once you remove the old piece (or at lease the collar), you will get a better view of what could be the issue.

 

[HermanTX]

And for the check valve, and to save space, I tentatively plan to use this Jandy 90-degree check valve. Any reason not to do that?
That is, would this addition be seen as an overall positive or a negative?

View attachment 640599

I had forgotten about the 90 deg check valve. I have never used it but have seen one or two. Just ensure you install it properly.
See below.

 

[TwinsPool]

Herman,
I just went out and took a closeup picture and it does appear that the collar/nut screws down onto the male threaded part above it. I guess we'll see when I take it apart how the sealing actually takes place. I'll attempt that either today or tomorrow. I may run to the pool store now to buy a new one. If I get it I will share how it works.


Thanks for the 90 degree instructions. I see how it must be installed from that.

 

[TwinsPool]

Here is a picture of the new copper-to-PVC connector. It appears to be similar to a SharkBite type of seal, where an O-ring between the outside of the copper pipe and the inside of the PVC pipe forms the only seal. My current (slightly leaking) connection is probably the same type, so the O-ring is probably what is failing. It will be interesting to try to get this type of collar/nut off of the copper pipe without scoring the pipe -- I'll have to fashion something to slide up into the collar to release the metal tangs off of the copper pipe.


In any event, I will be rebuilding essentially all the PVC plumbing between the copper pipe and the pump and will include the Jandy check valve and the union at the pump. Certainly (hopefully), this should fix any air leak problem that occurs in this stretch of suction piping.

Sometime tomorrow the check valve and the special pump union should arrive, so if it arrives early enough I will put it all together then.

 

[ol_whistle_britches]

I think what you’re talking about sounds logical. Kinda is what it is at this point.

And for the check valve, and to save space, I tentatively plan to use this Jandy 90-degree check valve. Any reason not to do that?
That is, would this addition be seen as an overall positive or a negative

Keep in mind those check valves typically require 1-3psi to overcome the internal spring. Not a big deal in a working system and not an improper application as you’ve planned, but if you’re already having a priming issue it’s possible that it may not help as much as you think. Just want you to be aware…

 

[TwinsPool]

Thanks, yes, I have read about the additional head that check valves can cause due to the springs. I've read that some of the experts on TFP (like JasonLion and bdavis466) remove their springs. I just watched a YouTube video showing that the spring(s) can be removed easily by just sliding out the pin that they (and the flapper) pivot on. I plan to go piecemeal: none removed (check PSI vs pre-check-valve, and function), one removed (check PSI and function, both removed (check PSI and function). They say that gravity and/or a small amount of reverse pressure is all that's needed to shut the flap on flapper-style check valves like the Jandy. The "two" springs are actually only one two-sided spring, but the tension of one can be removed by bending or cutting off the end of the spring on one side or the other.

 

[TwinsPool]

The Jandy check valve I received today had multiple cracks under the clear cover by the screws, so I had to return it (Amzn). I ordered another one (hoping for no damage), but It doesn't arrive until Wed 4/30 or Thurs 5/1. I'll post again after I receive it and replace the intake plumbing.

 

[TwinsPool]

Change of plan. I decided not to replace the entire plumbing and not to add a check valve. I can explain why if anyone is interested.

Long story short, I just replaced (and lubed) the sealing O-ring at the copper/PVC transition and re-lubed (silicone paste) the Hayward rubber gasket/O-ring at the union on the pump's inlet. The original copper/PVC fitting is exactly like the one I pictured in post #26 above.

The small leak at the copper junction was fixed, but there was still incomplete priming -- the water level in the strainer area (examined after stopping the pump or during low speed [1700 rpm] pumping) is almost to the bottom of the dome of the clear cover, but does not reach the dome. I don't detect air in the filter after running continuously overnight, but maybe air would go into the filter if the pump stopped and restarted with a new prime (yesterday I purged air after the last priming). I also added DE to the filter yesterday.

So, now I am worried that I may have a suction leak in the underground skimmer/main drain line to the pump (they join at the skimmer and one line goes to the pump). If I want to test for that, I presume I would have to do a pressure test on that pipe? I haven't done any test for pool water level leaks.

Another question I have: With this level of incomplete priming, does it require fixing, or is it something I can live with (assuming I don't have a significant leak in my pool water level)? The entire length of the suction line from the pool to the pump is under concrete slabs (back patio area). I would really hate to have to dig all that up.

 

[PoolStored]

Air in the pump basket on low speed is normal and usually caused by one of two issues.

1) Pump lid leak. Sometimes pump basket lids will seal better at higher RPM than lower RPM because the pressure in the pump basket is lower at higher RPM.

2) Outgassing. The pressure in the pump basket is lower than atmospheric so dissolved gasses in the water can come out of solution. The lower the pressure, the more outgassing that will occur. However, at higher RPM/flow rates, any dissolved air that comes out of solution will quickly get taken out of the pump basket because of the higher flow rate. If the RPM is low enough so the flow rate is lower than the rate at which air rises in the pump basket, the air will remain in the pump basket.

There is nothing you can do about #2 but for #1, lubing the pump lid seals and drain plug gaskets can sometimes improve the problem. Use a silicone LUBRICANT, like Magic Lube II.

As long as the pump does not lose prime, you should be fine. I have a 15 minute run at 3000rpm once a day schedule to purge my air bubble.

If you run at high speed for a minute or two (3000), does the air bubble go away?

 

[TwinsPool]

PoolStored,

Thanks for your input. The air gap in the top of the basket area remains there after running for 15 minutes at 3450 RPM (air never goes away). If I slow to 1700 RPM, the level of the water calms down and is just below the dome of the clear cover. Changing to 3450 RPM for 15 more minutes again does not change anything. The amount of air in the basket area stays the same no matter what I do. If I let the pump sit OFF for, say, an hour or more, the level of the water in the basket does not drop. From these results, you will agree that outgassing is not an issue in this case. It also appears I don't have a huge leak (as in the lid O-ring), or the level of the water would presumably drain somewhat.

I bought a new pump lid O-ring and and installed it with my 3M silicone paste. I am 99% sure that it is essentially the same as what other companies call silicone lubricant or silicone grease (it comes in a jar and never hardens and is not silicone sealant like comes in a caulking cartridge). It is designed for lubricating the installation of rubber parts like O-rings.

I have not removed the drain plugs and examined and lubed the o-rings, but I have run water from a hose over them while priming for a minute or more without any affect on the air problem. I can try removing/lubing them, but am not optimistic.

Do you think it may be in my underground (below concrete) copper pipe from this 1977 pool? I hope not, but I don't know where else to look (besides replacing/lubing the drain plugs).

 

[PoolStored]

If the pump runs with an air bubble and doesn't lose prime, I don't think you have a suction side leak. Let it run for a day and check it every so often. If the water level stays the same and you don't lose prime, move on.

 

[TwinsPool]

Just so I understand, when you say "lose prime", does that mean the pump essentially runs out of water and is starving for water (and probably makes a struggling noise)? I don't have that problem, but I do have a concern that I may be putting air into my filter during each priming event, although I don't know that for sure until I change the program from 24/7 running at 1700 RPM, to, say, 12 hrs at 1700 RPM (of course with a priming at each start). I will make that change and see if I will be getting air into my filter.

By the way, what is a typical time people use for priming?
I notice that my Hayward VSP pump instructions have this in their general instruction section for programming the pump (I'm not sure whether they just threw in a number or this is what they actually suggest):

 

[PoolStored]

Just so I understand, when you say "lose prime", does that mean the pump essentially runs out of water and is starving for water (and probably makes a struggling noise)?

Correct.

By the way, what is a typical time people use for priming?

Every pool is different, my prime is 5 minutes, but primes in about 2.5.
Time what it takes to prime and setup for 1 minute longer.

 

[TwinsPool]

Thanks!

I ran it overnight at 1700 RPM, but there is not a progressive increase in air in the basket -- it stays the same. So what you say about there not being a suction leak makes sense.

I will try running for about 12 hours a day at this low-ish speed (1700 rpm) and see if the air volume increases or not (and if air is going to the filter) due to the time off and daily priming.

While I've got you here, does this pump speed/time okay to you? I suppose everyone may have a different plan, but what do you think?

Thanks again!

 

[PoolStored]

See section 1.12:

Pump Basics - Further Reading

www.troublefreepool.com

 

[TwinsPool]

Thanks!

 

[ol_whistle_britches]

2) Outgassing. The pressure in the pump basket is lower than atmospheric so dissolved gasses in the water can come out of solution. The lower the pressure, the more outgassing that will occur. However, at higher RPM/flow rates, any dissolved air that comes out of solution will quickly get taken out of the pump basket because of the higher flow rate. If the RPM is low enough so the flow rate is lower than the rate at which air rises in the pump basket, the air will remain in the pump basket.

@PoolStored Thank you for writing this succinctly. I kept playing with this answer in my head and gave up on it when I started to think about partial pressures and gas laws. I couldn’t figure out how to say it correctly.

Outgassing was one of my thoughts for @TwinsPool, specifically because it looks like you have a change in diameter between the copper pipe and the 2” the pump is accepting. That will drive an additional pressure reduction and contribute to the differential between the atmospheric (pool) and the pump basket.

but I do have a concern that I may be putting air into my filter during each priming event,

I don’t worry about this. I believe the air relief valve at the top of my pentair DE is actually supposed to be somewhat self burping in normal use. I don’t remember if I read that in the manual, or if that’s just how mine ran before I rebuilt it.

You said previously you’ve been running the pump this way for months and never had an issue with it losing prime completely. At this point, I’d say you’re good. Sounds like a quirk. Even if you did have a suction side leak, based on what you’re seeing, I’d monitor and live with it.

 

[PoolStored]

Changing to 3450 RPM for 15 more minutes again does not change anything.

@TwinsPool
When was the last time you cleaned the filter?
Have you done an OCLT lately? Do one tonight...Link-->Overnight Chlorine Loss Test
A pump not being able to vacate air is indicative of a dirty filter, that may or may not be caused by algae.

You pump should be able to clear the air. With a suction side leak, or air coming in at low speed should happen after the pump fills.