- May 27, 2021
- 1,418
- Pool Size
- 17000
- Surface
- Fiberglass
- Chlorine
- Salt Water Generator
- SWG Type
- Pentair Intellichlor IC-40
Backwash procedure for pool with 2 filters
- Thread starter JPMorgan
- Start date
- May 3, 2007
- 18,150
- Pool Size
- 20000
- Surface
- Plaster
- Chlorine
- Salt Water Generator
- SWG Type
- Hayward Aqua Rite (T-15)
As I posted in #107 there are several possibility and yes it could be the wrong impeller or it could be something is stuck in the impeller. Both would alter the head curve. But the impeller might be just fine and it is one or more of the measurement methods that is wrong. Inspecting the impeller will either confirm or rule that out as a possible problem.
If we do this and get the same readings as before, then that rules out any problem with the incorrect reading on the gauges, right? That would then eliminate Operating Point C from mas985's post #107 above, right? That leaves an incorrect flow meter or a problem with the pump as the culprit, correct?
Maybe the wrong diffuser or maybe missing parts.
Maybe reverse rotation.
Lots of possibilities.
Maybe reverse rotation.
Lots of possibilities.
But all related to an issue with the pump (assuming the flow meter is correct).
A tech from the PC was here today addressing a leak. I was questioning the tech about this issue and he thinks that a plug in the pipe just before the flow meter may be causing the flow rate to register incorrectly (see photo). His "theory" is that there is a piece of the plug that extends down into the pipe which may be causing a disturbance in the flow right before the flow meter. He is suggesting to change that section of pipe to eliminate that plug. It seems doubtful to me that we are going to pick up 50 gpm by eliminating that plug (but who knows). Is that worth pursuing or is that not very likely to be causing this problem? The specs for the flow meter call for 30" of straight pipe (10 x pipe diameter) before the flow meter. This plug sits right at about 30".
Does this order of pursuing things to rule out make the most sense:
Does this order of pursuing things to rule out make the most sense:
- Pull apart the motor. Make sure all internal parts are the correct parts and that there is no damage to the parts
- Make sure the motor is wired correctly (all the items noted from James W's earlier post)
- Replace the pump suction and pressure gauges
- Replace the stretch of pipe where the flow meter is installed, including replacing the flow meter
Just take a video of the rotating shaft?
How do I check the RPM?
Power, voltage, amperage.... are these all things to have the PC check? (I'm no electrician.)
What is cavitation and what causes it? Better yet.... how do we avoid it?
The impeller, diffuser and seals were replaced less than 2 years ago. Could these parts be worn out again already? As I recall, the impeller was replaced two years ago becasue of the low flow rate we were experiencing at that time. This was before any new equipment was installed. (Maybe wrong parts were installed?) We were using an old style B&W flow meter back then. When we changed equipment, we had to install a new type of flow meter required by the state.
You need a Master Licensed Commercial Electrician who routinely works on three-phase power.
Anyone else is a waste of time.
A Pool Person will have no idea how to check three phase power.
Even most electricians have no idea.
Low pressure due to a blocked or undersized suction line.
Avoid low pressure.
The pump has a specified Net Positive Suction Head Required and you need to meet that specification.
With cavitation or corrosion, it is very possible.
Always a possibility.
Looks like something I'll have to assk the PC to check. What should the RPM be?
- May 27, 2021
- 1,418
- Pool Size
- 17000
- Surface
- Fiberglass
- Chlorine
- Salt Water Generator
- SWG Type
- Pentair Intellichlor IC-40
I agree with @JamesW. With a Pitot tube style flow meter this explanation could be plausible, but not with the style flow meter you have installed.
Cavitation/corrosion destroying a year old bronze impeller that runs seasonally is a remote possibility in my experience, but it’s still a very worthwhile endeavor to pull apart the pump for a visual inspection to rule out wrong parts, potential damage, rpm, mis-wiring etc. Anything is possible. I’ve seen plaster pieces sucked into a Pentair EQ750 7.5HP pump that reduced the flow to 1/3 its design curve. They made it through the impeller and out the returns….only God knows how, as they physically should not have fit into the return plumbing much less get spit out onto the pool floor through the return orifice. After that, flow restore to anticipated design spec.