SQE?

[mmancuso13]

Hello to the pump & well forum.

I have some Grundfos CU-301 / SQE questions, is this the right forum for those?

Do we have e any AQE experts out there?

Let me know and thank you

 

[mmancuso13]

Hello to the pump & well forum.

I have some Grundfos CU-301 / SQE questions, is this the right forum for those?

Do we have e any AQE experts out there?

Let me know and thank you

Typo - SQE experts?

 

[Valveman]

Glad to answer questions here.

 

[mmancuso13]

Glad to answer questions here.

Great thanks!

I have a Grundfos SQE with a CU-301 controller that was installed new in 2008.

The initial system had a 2G pressure tank and the pressure transducer is near or directly adjacent to the pressure tank.

Recently our original pump went up (lasted 14 years and maybe because we had / have quite a bit of granite grit from the initial well bore drilling) so I replaced it with a 15 SQE07-180.

At the same time I decided (maybe incorrectly) to upsize my pressure tank to a welltrol 202 XL because we have a lot of power failures (we are at the end of the line and get a lot of wind and other intermittent outages).

My thinking was that we would have 5-7gal of tank supply for flushes or quick hand washing without the well pump running.

Now I am getting some weak flow / intermittent flow issues that make the system unusable - there is nothing quite like a dribbling non shower…

FYI - we have e a rancher and our dual shower is at the far side of the house - ~75 feet or more from where rhe well line entered tue house and where the controller and PT are located.

I have checked and I have no controller faults, I checked my pre-charge on the tank and set it to 50psi but still no change. I also have the Grundfos go app and 301 dongle but don’t see any internal controller settings that could be adjusted to help my situation.

My questions:

Can I run the larger pressure tank and if so what adjustments need to be made to prevent the weak flow issue?

Based on reading the CU-301 manual it probably does not help that the pressure transducer is located adjacent to the PT and not across the house closer to the large flow need (the double shower). Is this throwing off the controllers ability to maintain / regulate pressure?

I have not put a meter in the pressure transducer to check the ma outlet to make sure it is not a bad pressure transducer but will do that now.

I do have the old small 2G PT and can always go back to that but would like to not have to to keep some extra storage water on hand for power outages but may have to if it does not work like I am seeing how…

Any thoughts or advice?

Thank you in advance,

Matt

 

[Valveman]

As with any water system, the pressure tank is not for storing water. The purpose of the pressure tank is to limit the on/off cycles for intermittent uses of water. The CU301 controller is supposed to start the SQE pump when the pressure falls 7 PSI below the setpoint, and fill the tank 7 PSI above the set point before the pump shuts off. But it doesn't wait for the pressure to drop 7 PSI if the pressure is falling fast. Even if you could count on the 14 PSI bandwidth, you still can't count on a pressure tank having any water when the power goes off. If you knew the power was going off and cycled the pump to make sure the tank was full, a 20 gallon size tank would have about 3.5 gallons to use as the pressure falls 15 PSI after a power outage. But not knowing when the power is going off the tank may only have a cup of water left and the pump was about to start. A 5 gallon jug of water in the closet is better insurance for having water when the power goes off. A backup water supply or a generator to keep the pump running is the only way to be sure and have water during emergencies.

What I normally see happen with the CU301 controllers is they loose the connection with the pump/motor. When this happens they resort to working like a regular pressure switch with 15 PSI between on and off. After a thousand cycles, if it hasn't made connection, it will finally show the "lost connection" fault.

The book says it should work with a larger tank. But I have heard from many people with the same problem. I think the CU301 sees the larger tank as additional load that is using very little water and tries to deal with it by reducing the pressure.

The pump has become known to be fairly reliable when used with as an SQ with a regular pressure switch. But the CU301 is known to give problems and not last very long. Replacing the CU301 with a regular pressure switch and using a Cycle Stop Valve to deliver the constant pressure needed makes the SQ pump more reliable and longer lasting.

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

 

[mmancuso13]

As with any water system, the pressure tank is not for storing water. The purpose of the pressure tank is to limit the on/off cycles for intermittent uses of water. The CU301 controller is supposed to start the SQE pump when the pressure falls 7 PSI below the setpoint, and fill the tank 7 PSI above the set point before the pump shuts off. But it doesn't wait for the pressure to drop 7 PSI if the pressure is falling fast. Even if you could count on the 14 PSI bandwidth, you still can't count on a pressure tank having any water when the power goes off. If you knew the power was going off and cycled the pump to make sure the tank was full, a 20 gallon size tank would have about 3.5 gallons to use as the pressure falls 15 PSI after a power outage. But not knowing when the power is going off the tank may only have a cup of water left and the pump was about to start. A 5 gallon jug of water in the closet is better insurance for having water when the power goes off. A backup water supply or a generator to keep the pump running is the only way to be sure and have water during emergencies.

What I normally see happen with the CU301 controllers is they loose the connection with the pump/motor. When this happens they resort to working like a regular pressure switch with 15 PSI between on and off. After a thousand cycles, if it hasn't mad connection, it will finally show the "lost connection" fault.

The book says it should work with a larger tank. But I have heard from many people with the same problem. I think the CU301 sees the larger tank as additional load that is using very little water and tries to deal with it by reducing the pressure.

The pump has become known to be fairly reliable when used with as an SQ with a regular pressure switch. But the CU301 is known to give problems and not last very long. Replacing the CU301 with a regular pressure switch and using a Cycle Stop Valve to deliver the constant pressure needed makes the SQ pump more reliable and longer lasting.

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

I thought as much…

The pump and co troller are fine according to the MI-301 dongle and I can watch to cycle speeds as it provides water.

I was wondering if was that the large tank was so close to the pressure sensor? I bet if I moved the larger tank away from the manifold and behind a check valve the CU-301 would act “better” with respect to pressure and flow.

Anyway, I swapped out the large tank back to the 2G with a pre charge of 50psi and flow is back to normal.

Thanks you for weighing in!

Matt

 

[Valveman]

Sorry for your problem. Yeah they seem to work better with the small tank. I started using variable speed drives to control pumps before 1990. Since then, every problem has been met with a "If this, VFD would act better". Every 18 months a new "generation" comes out with patches that are supposed to fix all the bugs of the last generation. The SQE has been around longer than most, as I think it started in 1999. But since then I think it is in generation 8 or 9 as they have made a lot of changes trying to fix problems like you mention. As technology advances they get better over time. But VFD's will never be able to work around the laws of physics or "mother nature". VFD's are good for many things. I use them in my production plant. But there are things about the centrifugal impeller that makes varying the speed counter productive. I know I am an old school Boomer, but what time taught me is that keeping the controls simple is the best way to make sure water comes out of the faucet when you open it. The more electronics, bells, whistles, dongles, etc, the less likely water will squirt out when you need it.