Pluming overhaul

sefrlw

Well-known member
Mar 25, 2008
130
Wake Forest, NC
That time of year again all. Good luck all with all your maintenance and may your water be balanced crystal clear!

I recently went through a pluming overhaul. I was pushing sand and rock out the waste port. So what has been done.

1.) All filter internals replaced
2.) All filter externals replaced.
3.) All pump seals replaced
4.) All screw in fittings replaced
5.) New diverter valves
6.) Added 2 back flow preventers one for bottom and one for skimmer.
7.) Puck feeder removed and thrown out.
8.) Nature 2 removed an thrown out.
9.) Leaking bottom drain lines replaced between pump and ground level. Found what I think was a leak in a 90 seam allowing air in.
10.) Skimmer line cut and repaired where I found a leak allowing air in the line.

It has been quite a pain in the rear. However very worth it. The entire reason for this was that oer the past 10 year I have had no luck keeping prime on my pump so it has run 24x7. I should have done this a long time ago.....

I have had this noise in my multiport valve for years.... I always assumed it was air in the lines and would go away after all the work I have done.
So what is this noise and why am I still getting it. I do not remember it when we fist put the pool in. I can make it go away by turning off my main return and only send water through my slide return. Nothing else makes it go away except my filter pressure going up.

 
Last edited:

mas985

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May 3, 2007
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So what is this noise and why am I still getting it. I do not remember it when we fist put the pool in. I can make it go away by turning off my main return and only send water through my slide return. Nothing else makes it go away except my filter pressure going up.
It sounds like cavitation to me. But that would be very unusual for the pressure side of the pump. Are you sure it is coming from the valve and not the pump? What is the filter pressure?
 

sefrlw

Well-known member
Mar 25, 2008
130
Wake Forest, NC
I am having this problem too! Hopeful for a vet to inform us all!
Will make sure I post a solution if I find one....

It sounds like cavitation to me. But that would be very unusual for the pressure side of the pump. Are you sure it is coming from the valve and not the pump? What is the filter pressure?
It is definitely the in multivalve. At 26 seconds you can hear it the loudest. hat is right where the mic was on my iphone. Could the pump be creating the noise and it travel up through the pluming to the multivalve and be heard there? Pump is running 11-20 PSI 18 PSI it quits making the noise..
 

mas985

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May 3, 2007
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If the pump was making the noise you would hear it close to the pump. The noise can travel but it would still be loudest near the source. But the only way you can get cavitation on the pressure side of the pump is if the water is traveling through a very narrow passage at very high velocities. So it could be that the mulit-port is passing water through a small orifice somewhere which is causing the problem. When the pressure in the filter rises, it makes it harder for the transition to cavitate.

If you take apart the multi-port valve, you should see pitting somewhere on one of the valve surfaces. That might show you where the problem lies. By I noticed that you did not replace the backwash valve nor any of the gaskets, is that correct?
 

sefrlw

Well-known member
Mar 25, 2008
130
Wake Forest, NC
If the pump was making the noise you would hear it close to the pump. The noise can travel but it would still be loudest near the source. But the only way you can get cavitation on the pressure side of the pump is if the water is traveling through a very narrow passage at very high velocities. So it could be that the mulit-port is passing water through a small orifice somewhere which is causing the problem. When the pressure in the filter rises, it makes it harder for the transition to cavitate.

If you take apart the multi-port valve, you should see pitting somewhere on one of the valve surfaces. That might show you where the problem lies. By I noticed that you did not replace the backwash valve nor any of the gaskets, is that correct?
Multivalve is all new. Pluming cut out unscrewed and removed from filter and replaced with new. Are the gaskets you are talking about the ones between the Multi and the filter? I am not sure if they were replaced. What is the backwash valve you speak of?
 

mas985

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May 3, 2007
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Maybe we are not talking about the same thing. A multi-port valve IS a backwash valve and looks like this:



The gasket is inside the valve. But since it is new, I doubt there is a problem with it. The old valve did the same thing right?

Can you also describe the plumbing after the filter? Maybe a picture of the entire equipment pad would help. Also, there is a small pipe on the opposite side of the multi-port. What is that for?
 

sefrlw

Well-known member
Mar 25, 2008
130
Wake Forest, NC
Ok here you go.

I am planning on replacing the T in the return and seat jets return with a 3way diverter just like the other two. I do not like that I cannot turn off the seat jets without turning off the returns. All pipes labeled in the pictures. The other pipe you ask about is the waste line...

I am also planning on replacing and reorganizing the pipes through the wall. It is very tight and need the reorg to fit the diverter.

Could it be that I do not have enough back pressure or too much flow due to the lack of the diverter to select seat jets on or partial.

And yess it is a mess at the moment.... :) I will clean it all up when done.....



 

mas985

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It looks like you currently have the skimmer turned off. If you turn on both the skimmer and the main drain, does that change the noise at all?

Could it be that I do not have enough back pressure or too much flow due to the lack of the diverter to select seat jets on or partial.
Possibly but when both the skimmer and the MD are on, then that should self correct some. Is there a large pressure change with skimmer only vs MD only vs both?
 

sefrlw

Well-known member
Mar 25, 2008
130
Wake Forest, NC
Sorry did not answer thoroughly. Noise happens with any combination until the pressure rises. I will go down a little if I simply select slide but it is still there.
 

mas985

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I would like to try and estimate the flow rate so can you tell me the following:

- Filter pressure with both the MD and Skimmer on

- Pump height relative to the pool water level

- Distance from the pool to equipment

Did you confirm that the backwash valve (i.e. Mult-port valve) was replaced recently?
 

sefrlw

Well-known member
Mar 25, 2008
130
Wake Forest, NC
Pressure after backwash 12 PSI MD and Skimmer on. All returns including slide on.
Pressure after backwash 22 PSI MD and Skimmer on. Slide only
Pressure after backwash 14 PSI MD and Skimmer on. Returns and seat jets only

Pump is 35 inches so call it 3 feet above current water level.

Equipment 13 feet from edged of pool.

Yes backwash valve is totally new like you pictured.
 

mas985

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Sorry one more follow up. When just the slide is on, does the noise go away?
 

mas985

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All the symptoms are pointing to cavitation but I can't think of why the valve would cavitate. Flow rate is not exceptionally high (~76 GPM). However, under certain conditions where there is a sudden transition (small orifice) there can be enough of a pressure drop to cause cavitation. But then again it would be odd for Pentair to have that sort of design flaw in the valve plus I would expect that to be a fairly common occurrence and reported by others.

Is the sound loudest inside of the valve or at the connections to the filter?

But since we know that reduction in flow rate fixes the problem, I might suggest that you replace the pool return eyeballs with small diameter eyeballs. That might be enough. Another option would be to replace the pump impeller with the 1/2 HP impeller which would also reduce flow rate and reduce energy consumption too.
 

sefrlw

Well-known member
Mar 25, 2008
130
Wake Forest, NC
The noise is loudest at the MP right where the pump feeds it.


Awesome to find out I am not alone. I was concerned it was something I did with my overhaul. I suspect it is since I indeed increases flow by replacing a few 90's with 45's and I removed the nature 2 which I considered a restriction. It indeed did it prior to the overhaul but that I thought was due to the large amounts of air I had due to some auction side leaks.

Something else that may or may not contribute needs to be looked at and I will soon. My diffuser had some debris in it that I did not have the knowledge to clear before putting the motor back on the wet end. Now that I know how simple it is to clean it I will also be doing that.