LAM
New Member
I'm aware that Flotec isn't the tank of choice, but until I have the need to replace this tank it's what I have. It's an 85 gallon FP1730 and can be isolated from the well and the house plumbing with shutoff valves on either side of the tank tee. The pressure tank/switch is located in a conditioned space inside the house and the well is located 400 feet downhill (mountainside house). The well is 120 feet deep with a 3/4 hp Grundfos. The drop pipe is galvanized and the buried (5 feet) water line is 1.5" PVC. There is approximately 515 - 530 feet of total piping and probably 270 feet of head from pump to tank. The well, controller and pump are 15 years old and everything else is 6 years old. For the first 9 years of use the well was pumped with a generator for recreational use - no stopping and starting the pump, just run once or twice per week in spring/summer. With that in mind:
Two weeks ago while doing annual maintenance I found the tank's precharge was only 10 PSI. Everything was working per usual but I brought the precharge back up to 2 PSI under cut-in, and I also rechecked cut-in/off settings. Ever since then then the tank has lost 5 PSI of water pressure overnight when it starts the night out at full capacity. For what it's worth the cut-in is 34 PSI, cutoff is 54 and precharge 32.
For the past few nights I have allowed the tank to fill until the pump shuts off and then have closed the shutoff valves on either side of the tee ... and the tank water pressure gauge still shows a 5 PSI drop in the morning. There is no sign of a leak around the tank and everything operates normally: no air in the system, no water hammer, no short-cycling, no unusual loss of water pressure during use and during testing the tank refills and empties normally.
The precharge is holding but yesterday I emptied the tank and pulled the schrader valve core to check for moisture. Rather than disconnect the tank from the plumbing and earthquake straps then tipping it over to check for water, I threaded a "mile" of yarn into the schrader valve and pulled it out to see if it was wet. No.
Could the bladder still be bad? Could a worn foot or check valve in the Grunfos, even with the tank shutoff valve closed, cause some water to drain back to the well until a vacuum formed in the water pipe? Or for that matter a break in the water pipe?
I'm stumped because I don't know how the tank can lose water pressure with the tee valves closed. I'd much rather have to replace a bad tank than pull the pump or install a new water line
Two weeks ago while doing annual maintenance I found the tank's precharge was only 10 PSI. Everything was working per usual but I brought the precharge back up to 2 PSI under cut-in, and I also rechecked cut-in/off settings. Ever since then then the tank has lost 5 PSI of water pressure overnight when it starts the night out at full capacity. For what it's worth the cut-in is 34 PSI, cutoff is 54 and precharge 32.
For the past few nights I have allowed the tank to fill until the pump shuts off and then have closed the shutoff valves on either side of the tee ... and the tank water pressure gauge still shows a 5 PSI drop in the morning. There is no sign of a leak around the tank and everything operates normally: no air in the system, no water hammer, no short-cycling, no unusual loss of water pressure during use and during testing the tank refills and empties normally.
The precharge is holding but yesterday I emptied the tank and pulled the schrader valve core to check for moisture. Rather than disconnect the tank from the plumbing and earthquake straps then tipping it over to check for water, I threaded a "mile" of yarn into the schrader valve and pulled it out to see if it was wet. No.
Could the bladder still be bad? Could a worn foot or check valve in the Grunfos, even with the tank shutoff valve closed, cause some water to drain back to the well until a vacuum formed in the water pipe? Or for that matter a break in the water pipe?
I'm stumped because I don't know how the tank can lose water pressure with the tee valves closed. I'd much rather have to replace a bad tank than pull the pump or install a new water line