Pressure verses Suction

[scottj]

I have a Gould J5SH shallow well pump with a Furnas Pro Control 69ES pressure controller. There is a pressure tank with a functioning pressure gauge and a flow meter on the suction side to measure gallons used. The water source is an underground tank , located approximately 10 yards from the pump, that must be filled with water via truck. The suction line runs underground, and supposedly well below the frost line, to the pump, located in a heated room. I am in the southern Colorado mountains at 7500 feet and the temperatures have been near 0 F at night and around 40 F during the warmest part of the day.

Last week I noticed the pump running continuously. Upon inspection, I found a warm pump motor, pump housing, and suction lines. I assumed that I had allowed the water source to run dry. I checked the tank and still had over 13 inches on the stick. As I was not here for the installation of this system, I assumned 13" must be below the tank suction line to the pump and ordered another 1000 gallons of water.

After receiving the 1000 gallons of water, I turned the pump on and immediatley the flow meter showed flow and the pressure gauge indicated building pressure. The pump automatically shut down at 60 PSI. Problem solved...

I woke up this morning to a running pump. Upon inspection, I found it again hot, running dry. I shut it down by forcing the pressure controller to open the contacts, let it cool off, then restarted the pump. There was flow and the pressure built to about 55 PSI, no more. The pressure controller was not shutting the pump down. So, I manually decreased the cut-out setpoint of the controller while the pump was running, and the pump shut-off at 55 PSI.

I left the pump in auto and the forced the pump to kick back on by reducing system pressure by opening a sink faucet. The flow meter showed flow and the pressure rose to 55 PSI but the pump would not kick off. Frustrated, here I am.

I don't know if my suction line is frozen somewhere between the tanks and the pump, or if my pressure controller is INOP. Whenever I start the pump, I show flow for a short period of time, then flow stops and the pump starts building pressure, never shutting down. I don't know how to verify if the line to the tanks is frozen. My next step is to clean the plastic line from the pump housing to the pressure controller to insure it is debris free.

Does all this sound familiar to anyone????

[Bob NH]

The water meter should be on the discharge side of the pump. There should be no unnecessary restriction on the suction side of the pump.

There should be a foot valve (a check valve with a screen) in the tank and no check valve between pump and pressure tank.

[scottj]

Granted, the system design is not perfect, yet has performed for several years without problems. Did you mention the check valve as a potential problem that could be causing cavitation? From a troubleshooting perspective, I need help. Anybody have any suggestions before I start spending money?

[Porky]

Bob NH is right, the water meter is usually on the pressure side of the pump, however must have been working OK for some time.

My thought is that when the tank ran out of water and the pump and suction ran hot, it caused the PVC fitting at the pump to shrink and leak air. This will cause air in the pump and prevent it from building maximum pressure.

I suspect that if you locate and repair the leak everything will be OK again.

A SUGGESTION: Install a pressure switch with a low pressure cutoff. Then when the pump runs out of water and the pressure gets below 20 lbs it will turn the pump off. Then all you have to do is hold the low pressure cut off lever up until you have water again and wallah, you've saved your pump and suction lines.

Also if you want constant pressure with a variable flow (like city water pressure) look up www.cyclestopvalves.com.