New pump install problems-help

Well, I had to replace my ancient 1HP pump becuase the seal started leaking. I figured this was a good time to get a 2-speed model with a little more "oomph".

I bought a 2-speed Hayward Superpump, 1.5hp, and am having some issues.


Here are my pool specs:

25,000gal inground
single 1.5" suction and return
35 sq. ft DE filter (Pentair)
Pool Pilot Saltwater chlorinator
no heater
Polaris 360 pressure-side cleaner (runs off the main outlet, no booster pump needed)
I dont know the head of the system but there is not a long distance between pool and equipment, maybe 6ft on suction side and 20 ft from equip. to pressure side.

My reasoning for upsizing the pump was to get a bit more pressure for the Polaris unit, which could just barely run adequately off my old 1HP pump. I figured when not using the cleaner I would just run on low speed, so the 1.5HP upsizing would not be a problem.

I respositioned the new pump for easier access and in the process had to plumb 2 extra 90 degree elbows into the suction line (imagine a big "U" shape from where the suction exits the ground to the pump inlet).

So now I have 3 separate problems- maybe all related.

-pump works but on low speed not enough flow to run the saltwater chlor. cell (shuts off on low flow).

-on both speeds there are a ton of little bubbles inside the pump trap, a few issuing out of the return line, and on low speed there is a big air pocket at the top of the pump trap that never goes away (I verified there is no suction leak, the pump holds a vacuum and a full trap full of water overnite too).

- after a few hours of running there is now an abnormal mechanical sound (like a hissing or buzzing) really noticeable on low speed. Sounds like the impeller is rubbing the inside of the housing or maybe a bad bearing. Doesnt really sound like what I imagine cavitation would sound like.

On the good side on high speed it does run my cleaner quite well (cleaner needs about 20 psi to function right).

So I think I need to do 2 things, in order of importance, to fix the problems:

1. Orient the pump just like the old one and get rid of the 2 extra elbows and extra distance in the suction plumbing

2. Try to get a 1HP version of the pump, and return this one due to the (impeller, bearing?) issues.

3. Hope that when everything is plumbed right, the low speed can run my SWG OK, otherwise I guess I will just run on high speed all the time.

Am I on the right track here? Is my pump cavitating? I would expect a "pebbles in the pump" kind of noise in that case, but the bubbles in the trap combined with no suction leak have me wondering. My old pump never did this, and ran the whole system OK as long as the filter was relatively clean.

Garv,
Can't answer everything but may help on a couple issues.
For the chlorinator I have no idea what flow it needs but is there a way you can jury rig a couple lines to your returns and measure the flow by dumping into a bucket or 'calibrated' trash can and timing the dump? If you could break the line that may be easier but then you don't account for the added flow resistance to the returns. Then compute gallons per minute. That would help someone answer the question about low flow to the cell.
Not sure where the bubbles in the pump basket are coming from, may be just trapped, but on low speed you probably don't have enough flow to purge the basket so don't worry about the large bubble. In that place it should not cause any additional noise and won't hurt anything. I assume it's just a bubble right at the top.
On the bearing noise, could be. It would cavitate at high speed. One thing to try is to wait until it does it, shut off the pump, open the pump basket lid to let the water drain out, then turn the pump back on and see if it makes the noise when dry. Doesn't hurt anything to run like that for a couple minutes. If it's a clearance that's changing when warm it will probably do it dry too unless the stresses on the components change because of pumping water, but I doubt it.
Best I can do for now. I'll check in later.
Al
Edit: Do you have a bypass mode for the filter? Don't know how DE filters are set up. When bypassed that should up the flow rate some to see if that changes anything.

I believe the SWG needs 20 GPM to guarantee proper operation.

Not so worried about the bubble at the top of the basket on low speed but the stream of small bubbles moving around inside the basket worry me more. I was wondering if not getting enough flow from the suction side could cause something like this- I plan to re-plumb the suction side to get rid of all the crazy elbows and see if that solves the bubbles/low flow problem.

Cleaning up the installation to remove the extra bends will certainly increase flow. I really don't understand why the cell needs 20 GPM to function. Is there a way to adjust the limit to a lower flow rate? A question, is the flow sensor sensing the flow correctly? I'd still try and determine what your actual flow rate is.
Al

Garvacious,

What were the specs on the old pump? HP & service factor and/or model #?

What was your filter PSI before and after pump change?

With 1 1/2" plumbing, you could be sucking some air into the system if the suction is much higher than what is was before. It is unlikely that the pump is cavitating because it takes quite a bit of blockage to do that.

The Superpump has a low SF so it shouldn't have much more braking HP than your previous pump. Unless, there is a good reason to upsize the pump I would stick with the same HP or even lower. You might want to consider a more efficient pump such as the Whisperflo or even Intelliflo. They cost more up front but will likely save you money over the life of the pump.

As for the SWG, it sounds like the flow switch isn't making contact on low speed. Try unscrewing the switch and adjusting the contacts (assuming that is the type of flow switch you have). Also, orientation of the switch can sometimes make a difference. Make sure it is pointed in the right direction.

My old pump was ancient, rusty, and seemed smaller in size than the superpump. The motor looked a bit newer like it had been replaced at some point. The motor was a 1HP Magnetek "E-Plus", I remember it was 6amps at 240V but never noticed the S.F. rating.

My old filter pressure was only about 3psi clean but I got great flow. I have no heater, only the DE filter and SWG.

With the 1.5HP superpump I get 10psi on the clean filter. Seems like a LOT of flow on high speed, almost too much without the Polaris cleaner hooked up.

Ordered a replacement 1HP unit to swap for the noisy 1.5HP, we'll see how it goes...I notice the 1HP superpump is only 5.8A on high speed, where the 1.5HP is 8A!