Intelliflo Vibration - Low Speeds

[AKAAB]

Simple question on a fairly simple system.

We bought a foreclosure six years ago and have rehabbed the pool from green pudding swamp to crystal clear without having to do anything with the old pump. I added an Aqua Rite Goldline SWG as soon as we drained the pool and we had it resurfaced two years ago.

Yesterday, I replaced my old 1hp coffee grinder (that's what it sounded like at the end) with an Intelliflo VS+VSRS (011017) and upgraded from a Hayward C900 to a C1200 filter. I was able to take out a bunch of unused PVC from where the previous owner must have removed/bypassed a heater and took out about 360° of turns to improve the flow a bit. The system tested out beautifully with no leaks and great flow. However, when I ramp it down to the lower rpms, below 1500rpm or so, the entire pump vibrates and shudders. As soon as I bump it up above 1500rpm it smooths right out.

I have 2" PVC from the 3-way Jandy valve to the pump and the main drain is 2". The skimmer and vacuum (1 1/2") are on a separate 3-way Jandy valve the feeds to the other side of the main drain valve.

Pump output to filter is 1 1/2" and return line from filter to pool is 1 1/2". (I could have done 2" pump to filter, but still would have the 1 1/2" return line to the pool.)

Any clues as to why it would vibrate at the lower speeds? Would increasing the pump-to-filter to 2" help? I'd still have the downsizing coming out of the filter, but perhaps that would be better? (Yes, I've searched the forum to no avail.)

As I said, it's a fairly simple system setup with no automation. After some reading here on TFP, I rewired the new pump to the hot wires coming into my timer so I could use the built-in timer function. It's not ideal, but I'm going to keep the salt cell on the old pool timer until I can find time to either add a control panel or build the relay/timer rig I've seen on TFP.

15x30 pool
Pentair Intelliflo VS+VSRS
Aqua Rite SWG
Three eyeball returns
One mystery return - probably old air jet
Main 2"
Skimmer and Vacuum 1 1/2"
Hayward C1200 filter
No spa, waterfall, water features, etc.

Cheers!

Paul A.
Jupiter, Florida

 

[AKAAB]

My wife loves being able to access the salt cell without scraping her knuckles.

 

[mas985]

I have read several complaints about the Intelliflo vibrating on low speed. Not many solutions though other than making sure the pump is anchored to the pad. I suspect there is some sort of resonance in the pump design.

 

[JasonLion]

Changing pump speeds often helps. The resonances are often only at certain speeds.

 

[AKAAB]

Changing pump speeds often helps. The resonances are often only at certain speeds.

I bumped up the minimum speed to get out of the vibration range, but I really wanted to be able to use the slowest speed for circulation in the afternoon. I really interested in why it would resonate at the lower speeds and how to rectify it so I can use the full range of the variable speed pump.

 

[JasonLion]

I don't know if this affects your situation or not, but the IntelliFlo is most energy efficient around 1000 RPM. Lower speeds use more total energy to move the same amount of water.

 

[Killer95Stang]

I noticed that Intelliflo's seem to all vibrate at certain speeds.. which is about 1200 - 1300 rpm. With your pump, I'm not sure if you have it bolted down to the pad? I can tell from your two pictures that their is a lot more flexibility in the piping with the larger hoop that you added above the new pump. If you shorten that hoop, or find a way to tie the two pipes together, you will get less noticeable movement in the pump.