Franklin Electric Sub Drive 75 Constant Pressure system

I have had a Franklin Electric Subdrive 75 Well Pump System for approximately 6 months. It has been working perfectly until now. For the past 3 days the water has stopped after a 5 minute shower. I checked the gauge on the tank and it was reading 15 (normally around 60). There were no red fault lights. The green light was solid. About 15 minutes later I checked it and the green light was flashing and the pressure was back to normal. This has happened the past 3 days.

If it is only 6 months old, you might give the installer a call for assistance.

I have heard nothing good about these variable speed drives, except from the people who are making money selling them.

it sounds like you're running out of water. But those things are suppposed to shut the pump off

I don't think I am running out of water because according to the manual, I should get a red blinking light indicating a fault if that happens. When it occured yesterday I started to take the rubber cap off the sensor and the pump started to run and came up to normal pressure. It has been fine so far today. I am suspicious of the sensor and waiting for it to happen again so I can bypass the sensor and see if it recovers again.

I don't know what sensor you intend to bypass but I hope you have a functioning pressure relief on the system, because when those controllers go awry, they can easily exceed safe pressures. Maybe you should leave it to an expert given that is should still have warranty.

You can actually replace those "sensors" with a standard 40/60 pressure switch. It will cycle much less than when using the "sensor" as they are actually just a pressure switch with only 1 PSI between on and off. Right now that sensor is cycling the pump 45 times per minute. If you use water 24 hours per day, that is nearly 2 million cycles per month. You can also use a CSV with those type systems, and it will take out all the cycling.

Constant pressure pumps are a nightmare and costly. Look into a Pside-Kick http://www.cyclestopvalves.com/pdf/psidekick-brochure.pdf. It will solve your problem with your constant pressure pump.