UPDATE - GUESS WHAT WE FOUND .......Pentair VS+SVRS Pressure

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rmklaw

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Aug 27, 2009
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Any ideas why my pressure at the pump gauge registers about 5-7 psi higher than at the filter? Clean filter, pressure at the pump is 15 psi and at the filter is 10psi. The plumbing goes from pump output 6" to a 3-way valve (to bypass filter as necessary). From valve goes to HIgh-Flow valve of Pentair Quad 100 filter.

Is it possible that the 3-way valve in close proximity to the pump output (6") is creating additional pressure? The reason I am concerned is because I am experiencing priming problems when the pump has not run for about 14 hours. When it starts, sometimes it does not prime. My vaccum (suction side) is about 5 and already checked the lines and no obstructions. According to Pentair, the filter pressure should not be lower than the pressure measured at the pump. Already changed gauges. Once it is running, I get 50 GMP with 2350 rpm.

Any ideas are appreciated. Thanks.
 
Re: Pentair VS+SVRS Pressure

I suspect you are correct because when it is trying to prime and does not, I start moving the 3-way valve to start partially bypassing the filter, and the pump starts priming. My concern is the T valve acting almost as a wall being so close to the pump output. I'll try to take some pictures.
 
Re: Pentair VS+SVRS Pressure

According to Pentair, the filter pressure should not be lower than the pressure measured at the pump.
Click to expand...
Of course pressure will be less at the filter than pump. I don't understand why they would say that. There are two reasons it is less at the filter. One because the gauge at the filter is 3' higher than the pump so static head is less. The second reason is there is head loss between the pump and filter. You can't avoid that. So the filter pressure is at least 1 PSI less than the pump and usually more that. Especially if you have valves between them.

Also, most backwash valves have a lot more head loss than 3-way valves and 5 PSI drop would not be uncommon.
 
Re: Pentair VS+SVRS Pressure

That is a good quality valve. When set to full flow in one direction, as yours is set, the flow restriction is almost identical to having a common 90 degree fitting (if one were used in the same place). That valve is not a problem.
 
Re: Pentair VS+SVRS Pressure

I agree with Jason, 3-way valves have very low head loss. However, backwash valves tend to have very high head loss and about half the head loss occurs on the input to the filter and half at the output. There are a lot of channels and turns in a typical backwash valve. I don't have specific data on yours but a Hayward 714 has about 9 PSI of loss at 50 GPM so around 4.5 PSI loss on the input section. Add 1 PSI for the filter height and you are at 5.5 PSI loss between the pump and filter.
 
Re: Pentair VS+SVRS Pressure

Makes sense. Then to the difficult problem which is why it fails to prime when it is off overnight. Checked both suction and return lines and don't seem to have obstructions. The problem started when I replaced the old SWB 72 filter with this new Quad 100 DE. Sometimes to get it to prime I have to turn the Jandy filter bypass valve coming out of the pump. Almost like the pressure is preventing priming, although, the pressure readings are fairly low. Any suggestions? Thanks.
 

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Re: Pentair VS+SVRS Pressure

Sounds like you have an air leak in the filter. Backwash valves can leak air into the plumbing while the pump is off but still not leak water out when the pump is running. Usually it is the spider gasket in the backwash valve. Was the valve reused from the previous filter or is it new?

Try this:

After full priming the filter and pump, release the air out of the filter until water comes out of the relief valve. Turn off the pump and listen near the filter and if you can hear bubbles going up the filter, then you have a leak somewhere. You can try the hose method to see if the leak can be found.
 
Re: Pentair VS+SVRS Pressure

It is brand new filter and brand new hiflow multiport valve. Thank for the suggestion. Makes sense. If you look at the second picture you will see that I have the autopilot sampling lines connected. In between the filter and the multiport valve and out in the suction side of the pump. Could it be that I am introducing air through the sampling lines when the pump is off?

Also dumb question, what is the hose method?
 
Re: Pentair VS+SVRS Pressure

Sure, that is a likely spot and a good place to check. Those connections have a tendancy to leak. Do you see any air in the pump basket while the pump is running?

The hose method is to pour water over a section of pipe/fitting with a hose and see if the air leak subsides. However, you need to hear the air bubbling into either the pump or filter.
 
Re: Pentair VS+SVRS Pressure

The answer to your question is YES. The pump never runs without air bubbles regardless of speed. The problem is to figure out wher are they coming from. I am thinking about asking Autopilot if I can place check valves in both sampling lines. Air always comes down from the solar when I shut the pump.
 
Re: Pentair VS+SVRS Pressure

If you have air in the pump basket while the pump is running, then the leak is on the suction side and probably from the Autopilot connection but putting in a check valve would not help. It is likely leaking around the fitting that goes into the pipe.

Other places where air can leak is the pump basket lid gasket and drain plugs. A little pool lube can fix that.

rmklaw said:
Air always comes down from the solar when I shut the pump.
Click to expand...
That is suppose to happen. The vacuum release valve opens and air allows the panels to drain.
 
Re: Pentair VS+SVRS Pressure

Thanks mark. I did the hose test, but nothing changed. I am going to check the suction side fittings. My concern with the Total Control is that any air from the return side solar goes through the sample lines and back to the intake. That is why I thought of the check valves. As it stands, I had to move the in sampling line from the SC60 manufold to the filter pipe because when the solar drained it was introducing air and I could never prime.
 
Re: Pentair VS+SVRS Pressure

Assuming I am following along correctly, there should be a check valve that prevents air from the solar system from getting back into the filter. The Total Control water sample line needs to be on the filter side of that check valve. Also, if that check valve was leaking, perhaps kept from completely closing by some bit of debris, it could account for what is happening.
 
Re: Pentair VS+SVRS Pressure

You are correct. There is a check valve. What happened before I moved the sample line is that it was connected to the manifoldwhich is after the checkvalve. Now as you can see in the picture I have it between the filter and the multiport valve (filter side of check valve as you suggest) to prevent air from the solar. I did remove the check valve flap and cleaned it. I can't help but think as you and mark said that there is some minor air leak which is allowing the pump basket to drain down between runs.
 
Re: UPDATE - GUESS WHAT WE FOUND .......Pentair VS+SVRS Pres

You would not believe this one. We found that the dealer delivered the wrong High Flow valve with the Quad 100. It should have been 261050 Triton Quad DE, but instead the installed valve was 261142 DE. In other words, the filter was running backwards. I took the filter apart and the inside of the cartridegs were half full with DE and the rest of the inside dirty. The bands holding the cartridge pleats had stretched and were loose. Pentair said that the cartridges were no good any longer.

The dealer made good. Gave me a new high flow valve, check valve and 3-way valve and tomorrow they are giving me 4 new cartridges. I spent all day replumbing since the valve and ports are completly reversed from the old one. Tomorrow I will test the system and report.
 

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