Confused by PSI with Recirculate > Filter

robbegginer

Member
May 17, 2017
12
Huntington, NY
Hello everybody. Learned a lot from this forum already just reading other posts. Just joined to post a new question about the pool at our new residence.

Why would the following PSI readings be shown for our Sand filter setup:

15 PSI on recirculate @ 3000rpm pump speed.
9 PSI on filter @ 3000rpm pump speed

I'd think Recirculate should be near 0, and Filter would be higher. It's an older 200 series Hayward sand filter, just replaced the sand 200lbs as per manual. When it's on Filter I can see water motion in the dome of the sand filter, and when it's set to Recirculate there is no water motion visible.

Hmmmm..
 

robbegginer

Member
May 17, 2017
12
Huntington, NY
On recirculate, the gauge on the filter should be zero as no water should be flowing to the filter.

Does the gauge go to zero when it's off? When a gauge fails, they can get pretty weird.
Yes, 0 psi when pump off. It's a new gauge replacing the old one stuck at 0 always.

Here is a photo showing 10 PSI when recirculating at 2400rpm.

Only thing I can think of is either the gauge is mounted on the wrong spot of the selector, or the selector was put back together wrong after some maintenance work.gauge.jpg
 

robbegginer

Member
May 17, 2017
12
Huntington, NY
Is the gauge on top of the filter or on the multiport?
Yes, on the side - image posted in another reply.

Interesting. So is it correct to say there is a "resistance" during recirculate of about 10 PSI when @2400 rpm?

Also, how do we interpret the PSI reading when Filter is selected. If it reads 5 PSI @2400 on filter, is it really 5 + 10 = 15 PSI?

The top of the sand filter has a smokey dome with a pressure release thumbscrew on the top. Would it be better to have a gauge there?

Thanks.
 

duraleigh

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Would it be better to have a gauge there?
Yes, that's where they belong. I would leave the old one in and buy a new glycerin filled one TFTestkits.net for the top of the filter. about 2-3 wraps of teflon tape and screw it in by hand.....not tight at all.
 

mas985

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May 3, 2007
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If you read through the S200 manual (#6), with the VariFlo valve and a pressure gauge, according to the manual, the pressure is suppose to rise as the filter gets dirty which means the gauge has to be on the input to the filter and not the output. So in recirculate, the pressure should drop, not rise. What am I missing?

https://www.hayward-pool.com/pdf/manuals/S200.pdf

https://www.hayward-pool.com/pdf/manuals/VariFloMultiportValve-SP0715.pdf

I just noticed that the OP's gauge is not in the same position as what the manual says it should be.
 

Bama Rambler

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Well slap me down! That'll teach me to look at valves on the interwebs! I removed some incorrect info so as not to cause confusion in the future.
 

mas985

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May 3, 2007
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Pleasanton, CA
But we still don't know why the OP is experiencing the opposite effect.


robbegginer, is there another 1/4" NPT TAP that is right below where it says Hayward VariFlo Valve?

If that isn't the problem then it could be a torn spider gasket.
 

jblizzle

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May 19, 2010
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Look at the screw on the left of your picture. There's a flat side in the plastic does that line up with the flat side on the filter. That would confirm that the valve is in the right position.
 

robbegginer

Member
May 17, 2017
12
Huntington, NY
But we still don't know why the OP is experiencing the opposite effect.


robbegginer, is there another 1/4" NPT TAP that is right below where it says Hayward VariFlo Valve?

If that isn't the problem then it could be a torn spider gasket.
There is not currently a tap, just a solid plastic circle. But it looks like it is designed that it could be drilled and tapped. The current gauge is mounted in the center of another plastic circle, just like the one below the Hayward VariFlo label. I'm attaching a photo which shows the empty circle, the current gauge mount is in the center of an identical round flat spot.

As to putting the gauge on the top of the filter, I've seen many photos of other models having that. This model, as shown in the pdf manual a poster linked to, has a thumb screw air release valve in it. It's much wider diameter and much thicker thread that a air gauge, not sure if an adapter is even available.

I've never seen the inside of one of these. Is it just the six screws to check the gasket?

Note: when on Recirculate the filter dome shows nothing, when on Filter the filter dome shows all of the water splashing.

gaugeCloseup.jpg
 

mas985

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Seems to me the gauge is in the wrong location although it could have been an old design. But yes, it is just the six screws. You can check the location of the gauge too while you are at it but since it is over the waste pipe, I am not sure what it would be measuring.

Can you step back and take a picture of the valve with pipes going from the pump. It almost looks like the return and pump pipes are swapped which would explain the pressures you are seeing.
 

robbegginer

Member
May 17, 2017
12
Huntington, NY
Seems to me the gauge is in the wrong location although it could have been an old design. But yes, it is just the six screws. You can check the location of the gauge too while you are at it but since it is over the waste pipe, I am not sure what it would be measuring.

Can you step back and take a picture of the valve with pipes going from the pump. It almost looks like the return and pump pipes are swapped which would explain the pressures you are seeing.
You're right about pump and return being switched. My fault, I wrongly assumed that the automatic chlorinator's input and output would be on the same side of the selector.

There is not an emoticon that can describe my combination of embarrassment and joy. At least my filter is the best backwashed on the East coast so far this season. Sure hope the moderators are able to keep the ribbing down to a moderate burn.

Thank you very much!