Time for a new pump

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Even if the valve is fully closed, the pressure will not get high enough to damage the filter. Maximum head on that pump is about 85' or 37 PSI. Filters are rated to 60 PSI. It wouldn't be good to run the pump too long that way but it would survive for a while.
 
Pentair ratings

Mark

Per the Clean and Clear manual:

"The maximum working pressure of this filter is 50 p.s.i. Never subject this filter to pressure in
excess of this amount, even when conducting hydrostatic pressure tests. Pressures above 50 p.s.i.
can cause the lid to be blown off, which can result in severe injury, death or property damage."

This is probably a bit of CYA. I figure if some future person moves the handle they will quickly figure out to move it back based on the sound.

I spent some more time this afternoon trying to back-flush both the 2" skimmer line and the 1-1/2" cleaner line. No real improvements.

My only consolation in this is that the "experienced tech" wanted to put in a 1 HP Sta-Rite which would have probably imploded by now with the cavitation. What really frosted me was when I asked the shop that I bought the pump from what it would cost to have a tech come out, they quoted $110. That's more than I pay to see my Dr.!

I didn't think pools were brain surgery but then again...maybe some there is some voodoo or "black magic" to all this. :lol:
 
Sorry, I should have said "can be up to 60 PSI" but still 50 PSI is much higher than 37 PSI.

I am still concerned as to why the suction head seems to be so high. 19' of 2" pipe should not be producing that much head loss. Do you happen to have a suction gauge that can be put on the suction side drain plug of the pump?
 
I think it's a question of balance

Mark,

I've been trying to approach this logically. I'm the first to admit I know squat about hydraulics. Here's what I think is going on.

I've got no suction side blockage and a very short run so then only way I could get more suction side supply is to put the pump at the edge of the pool. To me this says the pump is getting all the water it can since the intake port is only 2" anyway...same size as the line. The problem is not suction side head loss, it's lack of discharge head loss.

My discharge side head loss is also so low (around 14' according to my updated version of the Engineering Toolbox worksheet) that the pump has nothing to "push against", even though it was designed to work against some reasonable amount of head loss (which to me says resistance or back pressure...i.e. something to push against). So it's pulling the water out of the intake chamber faster than the 2" intake port can supply it and thus we get a vacuum and cavitation. Remember a Clean and Clear 520 filter can handle 150 GPM so there is no loss from the filter. The pipe and fitting loses are small too.

I went ahead and ordered the two port Jandy Neverlube (good price from Westside Wholesale). It should be here Monday.

As I understand it, the Whisperflo is considered to be a "high head" pump which I guess means it needs to be installed in a situation with lots of head loss? And somewhere I read about needing a high head pump if you had a suction side cleaner, which I do. Go figure.

I'll post results when available. Meantime any other suggestions are more than welcome.

Rich
 
Engineering Toolbox does not have equivalent lengths for filters, skimmers, and Jandy Valves. Filters and skimmers (basket w/float valve) have fairly large head loss and from data I have is the equivalent to 50' of 2" pipe each. A Jandy valve is about 25' per Jandy data. So I bit the bullet and added up the pieces:

Suction (ignoring the main drain)
Fittings: 17'
Skimmer: 50'
Valve: 25'
Pipe: 19'
Total: 111' of equivalent pipe

Return Side Pad
Fittings: 8'
Filter: 50'
Pipe: 2'
Total: 60' equivalent pipe

Return to pool
Fittings: 17'
Eyeballs: 20'
Pipe: 60'
Total: 97' equivalent pipe

Total Equivalent Length: 269'

The plumbing curve crosses the pump head curve at about 88 GPM @ 32' of head. Suction head is 14', return head about 19'. So suction head is about 43% of total head which is really high and no wonder the pump is noisy. So you are right that isn't a blockage and that there is probably no other solution than to add head to the return side, short of replacing the suction pipe.
 
Toolbox constants

Mark

You are totally right, there are no figures for the usual fixtures and fittings you see in a residential (or even commercial) pool. I did find a set of numbers at a university site in the Netherlands which did give some numbers for gate valves at various stages of closing. Pentair does publish a curve of "pressure loss" in psi versus "flow" in gpm but if the lowest common denominator is feet of head loss how do we get from there to where we need to be? It's funny, I was assured by the folks at my local supplier that all of their techs were trained in the equivalent length method but since the retail guy didn't know what it was my warm and cosy feeling was (shall we say) cavitating.

The other problem with the Toolbox workbook is you need to provide a GPM figure which I frankly have found no guidelines on how to determine (other than perhaps turnovers, which with different sizes of suction lines is a mystery). I would think there are some folks out there with (as an old work mate used to say) brains the size of planets who could come up with a model that said, "I have this piping and fittings, these fixtures and this sized pool. I want to turn it once per day. Which friggin' pump do I need?" Until that is possible, lick your thumb, turn it into the wind and make a (hopefully lucky) guess.

Rich
 
Re: Toolbox constants

Rich Purdum said:
The other problem with the Toolbox workbook is you need to provide a GPM figure which I frankly have found no guidelines on how to determine (other than perhaps turnovers, which with different sizes of suction lines is a mystery). I would think there are some folks out there with (as an old work mate used to say) brains the size of planets who could come up with a model that said, "I have this piping and fittings, these fixtures and this sized pool. I want to turn it once per day. Which friggin' pump do I need?" Until that is possible, lick your thumb, turn it into the wind and make a (hopefully lucky) guess.

Rich
Click to expand...

Actually, I already did what you are suggesting. I built my own Excel model and it uses the Darcy-Weisbach hydraulic equations and can tell you the operating point for any pump and any plumbing system plus how much energy it will use. That is what I have been using to come up with the numbers that I have posted. The problem I had was I didn't quite understand your plumbing setup but once I figured out that, the model came in pretty close to the PSI you were experiencing. However, one of the problems with any kind of modeling is that you have to have good data for the pump and plumbing and sometimes that is hard to come by. Even the equivalent lengths on the ET web page may not be all that accurate if the plumber did a bad glue job. Normally, I like to calibrate the model with actual pump suction and return pressure measurements to make sure the model is accurate. Still, the model came in pretty close with an estimate of 19' of head vs about 17' of head via the pressure reading (note: you need to add 3' for the filter height when converting pressure to head).
 
Suction side readings

Mark,

Is there an easy (and not too expensive) way to plumb in a vacuum gauge on the suction side? If so, would it be worth it to help keep my suction/discharge head in balance?

As for your model, remember that they are only to approximate or predict reality, not to be it. If yours is getting as close as you say, I would call that pretty good.

Rich
 
A vacuum gauge can be connected to the suction side drain plug, usually 1/4" so no serious modifications needed other than a vacuum gauge and 1/4" connector. But that would simply confirm the problem which I think you already know. When you add a valve to the return side, you will be able to hear when you have it set "right". However, it doesn't hurt to verify it with measurements if you are so inclined.
 
Vacuum gauge readings

So, if I can find a vacuum gauge I suppose I want one that reads out in PSI. I noticed one made by American Granby at Amazon for not too much money. It reads to 30 PSI (although the text says 30 HG). I believe I would want to be sure my discharge side PSI is higher than my suction side, or maybe they should be fairly close together. What should I be looking for on the readings?
 

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Vacuum gauges will usually read out in inches of mercury or in. Hg. Sometimes they will be dual gauges which read out in PSI as well as in. Hg. Sears carries a pretty reasonable one for automotive use but you can find them on Ebay/Amazon too.

If you put the gauge on the suction side, you can convert the in. Hg. to head by multiplying the value by 1.13. On the pressure, I think you already know this, you multiply PSI by 2.31.

Based upon the model, the suction side should read about 10" Hg. but I also estimated filter pressure to be about 7.8 PSI which is a little high from what you are seeing so that means suction head is higher than what the model says so expect it to be more than 10" Hg. To get to 6 PSI for the filter, I have to add about 150' of equivalent pipe to the suction side. Then the suction is around 21" Hg. which is quite large. This is one of the reasons, I still think there might be an issue with the suction side but we will see with the measurements. The filter gauge could be off as well so if you get a gauge that will read both PSI and in. Hg. then you can double check the results.
 
OK, so a vacuum gauge from Leslie's Pool is now installed where the drain plug was located on the strainer housing on the Whisperflo.

The vacuum is hovering around 9 HG. The pressure gauge on the filter is a hair under 8 PSI. The needle on the vacuum is fluttering a tiny bit which I assume is normal.

If I use 'Bama's figures, that gives me 4.4 PSI on the suction side. I have the far end eyeball return outlet completely blocked which gave me a slight bump in the pressure on the filter from previous posts and a slight reduction in noise.

I had the LOML observe both gauges when I manually blocked the first return outlet (difficult to do since it popped out of the wall again) and she thought both went to 10.

Not sure if these figures jive with what Mark was thinking about a suction side problem.

Meanwhile I'm running the pump for short spells to keep the pool stirred up until I can get this issue sorted out. I'm afraid of cavitation damage. PITA.

Rich
 
Actually, it is -4.4 PSI but I would stick with in. HG.

Can you do the same measurement with all of the returns open? It is hard to figure out what is going on if you don't stay with consistent setup. Also, make sure the vacuum is closed with just the skimmer and main drain open.
 
More readings

With the end of line eyeball re-installed and the cleaner shut off, I get 13 in HG at the pump and 6.5 PSI at the filter.

Here is a diagram of the piping and fixtures:

Visio-Poolpipingandfixturesv2.jpg


Here is a table with the fitting count and pipe runs:

Visio-Poolpipingandfixturestable.jpg


Hope this helps some.

Rich
 
That helped a lot. Much closer now to what you are seeing. I get 12.9 in. hg. and 7.1 PSI for filter pressure. I think it does show that it is operating as it should. Is your pad elevated above the pool? That can also affect the readings.

BTW, did you find any eyeball replacments that would fit? That would be the easiest solution.
 
Eyeball fittings

Mark

The Jandy valve has arrived at the UPS South City location and will be here probably tomorrow afternoon (I very seldom get a morning delivery from them for some reason). Rather than running back and forth to the pool store trying to get the head required from smaller eyeball outlets, I think it's easier at this point to just slap the valve in (downstream from the filter if that's an OK location) and dial up the head until the pump goes quiet. At that point I'll see how the eyeball streams are doing and perhaps put something smaller at the first outlet (as suggested by Jason). The shallow end needs a lot of help to get surface movement toward the skimmer at the far end.

Do you have any idea what the required suction HG and discharge PSI readings might be to get the pump into it's normal operating range? Just curious.

I'm a hopin' an' a prayin' the valve does the trick.

Rich
 
Success (sort of)

Got the valve installed this morning. UPS didn't show up until around 5:30 yesterday...I must be one of their last stops.

I seem to get the best balance between impeller noise and pipe noise with the Jandy about 1/3 of the way closed, with the suction side Jandy balanced to get the Kreepy to move at a decent pace. With this balance, the pressure on the filter is 11.5+ PSI and the vacuum on the pump is around the same as before (8 to 10 in. HG) the valve install but my perception is that it's fluttering is a lot more pronounced.

The whole system is still a lot more noisy than I was hoping for. I'd like to find some way of approximating my GPM flow as that might allow me to dial back hours of operation and confine them to times when the pool is not in use. I know I must be getting more than with the old Hayward, just don't know how to figure out total head given the Jandy. If I could do that I presumably could just use the performance curves for the Whisperflo as a starting point. (The Jandy did have a feet of head rating on the bottom of the housing, I recall it was 2.2 but I would imagine that is with it wide open.)

I recently got one of the new "smart meters" and it looks like the new motor is drawing around 1500 watts. To bad I wasn't able to get a reading on the old Hayward motor.
 
Rich I think you have everythiing you need to determine GPM. Total head is approximately the following:

Suction Head (ft) = Pump Vacuum (in Hg) * 1.13

Return Head (ft) = Filter PSI * 2.31 + 3

Total Head (ft) = Suction Head + Return Head

Look up GPM on head curve.
 

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