Pentair question

[JEK]

I have a Pentair well pump with a Pentek Intellidrive. Recently the water pressure goes down to almost nothing before it comes back to normal. what is wrong? I have replaced the pressure tank.

 

[havasu]

@Valveman to the courtesy phone please!

 

[Valveman]

Sorry for the delay. Hands full keeping the granddaughter again this weekend. We were just looking at the eclipse with the welding helmet.

Anyway, sorry for your problem. Which, could be one of many things. The pressure tank probably has nothing to do with it. To generalize, your problem is the VFD. Even though the Pentek Intellidirve is one of the best VFD's available, something about it or because of it will most likely be the problem. Many so called variable speed drives don't even vary the speed. They just quickly ramp the pump up and down to achieve the same effect.

With a normal well or booster pump control, there is only one mechanical pressure switch. With the hundreds if not thousands of electric and electronic parts in a computerized VFD it just leaves that many more opportunities for a failure. Failure modes are built into nearly every product we purchase, so we have to purchase them over and over, keeping the cash flowing for the manufacturers. A VFD is just a way to make people think they are doing something smart when they are really buying into a planned obsolescence scheme.

Now you are stuck with a VFD because you have a three phase motor and most likely extra small wire in the well. Until you decide to change out to a single phase motor and replace the wire with large enough to run a single phase motor, you will have to keep the VFD working as it is what converts your normal single phase house current to three phase and makes the smaller wire possible.

Having said all that, the Pentek should have some information on the display. It should show if the pump is drawing low, high amps, or if something else is the problem. They teach pump installers that they no longer need to know how pumps work, just how to read the display on the VFD. It could also be as simple as crud building up on the pressure transducer or cooling fan. If the transducer has a delayed response, so will your water pressure. If the fan stops cooling the VFD, it could give lots of different problems. Watch the display while the pump is working and see what you can find out.

https://cyclestopvalves.com/pages/vfd-repair-kit

 

[JEK]

Sorry for the delay. Hands full keeping the granddaughter again this weekend. We were just looking at the eclipse with the welding helmet.

Anyway, sorry for your problem. Which, could be one of many things. The pressure tank probably has nothing to do with it. To generalize, your problem is the VFD. Even though the Pentek Intellidirve is one of the best VFD's available, something about it or because of it will most likely be the problem. Many so called variable speed drives don't even vary the speed. They just quickly ramp the pump up and down to achieve the same effect.

With a normal well or booster pump control, there is only one mechanical pressure switch. With the hundreds if not thousands of electric and electronic parts in a computerized VFD it just leaves that many more opportunities for a failure. Failure modes are built into nearly every product we purchase, so we have to purchase them over and over, keeping the cash flowing for the manufacturers. A VFD is just a way to make people think they are doing something smart when they are really buying into a planned obsolescence scheme.

Now you are stuck with a VFD because you have a three phase motor and most likely extra small wire in the well. Until you decide to change out to a single phase motor and replace the wire with large enough to run a single phase motor, you will have to keep the VFD working as it is what converts your normal single phase house current to three phase and makes the smaller wire possible.

Having said all that, the Pentek should have some information on the display. It should show if the pump is drawing low, high amps, or if something else is the problem. They teach pump installers that they no longer need to know how pumps work, just how to read the display on the VFD. It could also be as simple as crud building up on the pressure transducer or cooling fan. If the transducer has a delayed response, so will your water pressure. If the fan stops cooling the VFD, it could give lots of different problems. Watch the display while the pump is working and see what you can find out.

https://cyclestopvalves.com/pages/vfd-repair-kit

Valveman,
Thankyou for the insight.
I'm pretty sure it's a 10 gauge wire, but will double check. There are no error codes showing on the controller. I'll check the amp draw. For a while we were getting air in the water, but that seems to have cured it's self. I changed to the VFD because I use it for my Geothermal and Domestic and couldn't come up with a better solution. I have a Gould 1 phase pump that I could put down there & try a Cyclestopvalve, that was my original plan but my well Guy who is a friend talked me into this. It works fine but the pressure drop drives me crazy!
I'm glad I found this Site.
thanks again.
Jack

 

[wpns]

Don’t know about VFD, other than how it’s supposed to work, but what’s the pre-charge on your pressure tank? This sounds like the classic case of precharge not being sufficiently below the cut in pressure

 

[JEK]

Don’t know about VFD, other than how it’s supposed to work, but what’s the pre-charge on your pressure tank? This sounds like the classic case of precharge not being sufficiently below the cut in pressure

I set the new pressure tank to 42lbs or 70 percent of 60. The old pressure tank had no pressure so I replaced it, but out of curiosity I inflated it and it seems to hold pressure so I’m not sure how it lost pressure.
I will re check the pressure.
Thanks for your reply
Jack

 

[wpns]

And 60 is your cut-in pressure? Again, I know what VFD is, but have no actual experience with it. If it's slow to start _and_ the pressure drops below your precharge, then it'll look like it drops to nothing.

 

[Valveman]

I have a Gould 1 phase pump that I could put down there & try a Cyclestopvalve, that was my original plan but my well Guy who is a friend talked me into this. It works fine but the pressure drop drives me crazy!

As they say, with friends like that you don't need any enemies. Lol! No really, I don't blame him a bit. Most pump installers have been force fed the VFD Kool-Aid by the pump manufacturers and suppliers. They really think they are doing what is best. I don't blame the pump manufacturers and suppliers either. For them the VFD is the goose that laid the golden egg. People believe a VFD will save energy, so they pay a lot extra and continue to pay to keep a VFD system working. Pump installers need a situation like this to help them see the light. They can either continue to make a lot of money selling VFD's and have many of their customers mad at them, or they can sell Cycle Stop Valves and have all happy customers but not make nearly as much money. It is good that this is happening with a friend, instead of the water system for the entire Texas Tech Hospital as happened to me. They were not nearly as forgiving to me as you are being with your pump installer friend.

Air in the system can happen by more than one way. Pumping the well dry or a hole in the drop pipe are the most common ways. But those two symptoms do not cure themselves. Another way is that the VFD is not shutting the pump off when it should, and the water was just getting churned up until it makes air. If that was just a glitch, which happens a lot with computerized systems like VFD's, and now the VFD is working as it should, that could sort of cure itself. But anyway it happened it should have caused low amperage and the VFD should have shut the pump down. The low amp setting may not be correct. With all the settings necessary for the Intelitech VFD that would not be unusual. One thing good about the Intelitech is that is has so many adjustments possible, unlike some of the other brands that have even more problems because they were made to be easy to set up and have very few adjustments. But having so many adjustments is also one of the problems with the Intellitech, as they all have to be set correctly.

#10 wire will run a 2HP for 390' or a 1HP for 630' and you already have the single phase motor you need. I would make my "friend" fix the problem or replace that three phase motor with the single phase you have so you can use a Cycle Stop Valve instead of the troublesome VFD. I agree with an open loop geo system you need constant pressure from your well pump to keep it from cycling to death. The Cycle Stop Valve will be just as efficient, cost less, and will make the pump and entire system last several times longer than any other method of pump control.

Here are a couple of videos I made many many years ago that are still pertinent to the subject today. Sorry for the old timey background music. Also a funny one on what we hear from most pump installers these days after they have drank the Kool Aid. Lol!

 

[JEK]

And 60 is your cut-in pressure? Again, I know what VFD is, but have no actual experience with it. If it's slow to start _and_ the pressure drops below your precharge, then it'll look like it drops to nothing.

yes 60 is the cut-in pressure, I think I'll raise it a bit and see if it helps.
Thank you for the replies.

 

[Valveman]

If the cut in or pump on setting is 60 PSI, a 42 PSI air charge in the tank should give plenty of time for the pump to get up to speed. But if the pump really comes on at 60 PSI and there is still a delay in water even with 42 PSI air in the tank, you will need to increase the ramp up time in the VFD. It could also be a problem of having more than one check valve, and you are waiting for the water to get from the pump up to the second check valve. The only check valve needed is the one down on the pump.