Sources and simplifications
Every reference cited on this site, and every place a figure idealizes the real system.
References§
- (2019). Well-X-Trol: Next Generation Well Tanks Featuring Antimicrobial Protection (specifications and ESP quick sizing table), form MC 7025 (04/19). Amtrol, West Warwick, RI. manufacturer data sheet Drawdown at 30/50, 40/60 and 50/70 psig for WX-101 to WX-350 (e.g. WX-202, 20 gal: 6.2 / 5.4 / 4.7 gal); factory precharge 38 psig; sizing table built on 1-minute run time for pumps up to 3/4 hp and 2 minutes above; note that drawdown depends on temperature and pressure. (How the tank works)
- (2019). Well-X-Trol Installation and Operation Instructions, 9015-868 MC10185 (06/19). Amtrol, West Warwick, RI. manufacturer manual How a well tank works (air above the diaphragm compressed as water enters); set precharge 2 psig below cut-in (38 psig for 40/60); adjust only with the tank drained and the system off, at ambient temperature; explosion hazard warnings; only licensed professionals should check or re-charge; licensed professional inspection yearly. (How the tank works)
- (2019). Chemistry 2e, §9.2 Relating Pressure, Volume, Amount, and Temperature: The Ideal Gas Law. OpenStax, Rice University. textbook Boyle's law: at constant temperature and amount, the volume of a gas is inversely proportional to its pressure (PV = constant); ideal-gas assumptions. (How the tank works)
- (2008). Guide for the Use of the International System of Units (SI), NIST SP 811, Appendix B.8 Factors for units listed alphabetically. National Institute of Standards and Technology. standard Standard atmosphere = 1.01325 × 10⁵ Pa; 1 psi = 6.894757 × 10³ Pa; so 1 atm = 14.696 psi. (How the tank works)
- (2014). WellMate In-Line Pressure Tanks data sheet, WM01 Rev D. Pentair, Milwaukee, WI. manufacturer data sheet Drawdown volume multiplier chart 'based on Boyle's Law' (e.g. 20/40: .35; 40/60: .25); tank size = pump gpm × minimum run time ÷ multiplier; recommends at least 1 minute run time. (How the tank works)
- (2025). HYDRO-PRO Tanks: Cross Reference and Sizing Guide, CRSGTANK R2. Xylem Inc., Seneca Falls, NY. manufacturer data sheet Sizing for one-minute ('adequate') and two-minute ('recommended') pump run times at 20/40, 30/50 and 40/60; 'Precharge at 2 lbs. below cut-in setting of pressure switch.' Revision R2, dated 3/2025 in the footer. (How the tank works)
- (2024). Diagnose and Repair Air Discharge at Faucets and Fixtures. InspectApedia. reference website Causes of air at the taps on a private well: falling well water level, a leak in the drop pipe, a failed air-volume control, a burst bladder (the tank then waterlogs and the pump short-cycles), a check valve that lets water drain back. Year approximate (page undated; read 2026-11-10). (How the tank works)
- (2026). AIM Manual: 60 Hz Submersible Systems, Application · Installation · Maintenance, 2026 edition. Franklin Electric Co., Fort Wayne, IN (copy hosted by the Nebraska Department of Water, Energy, and Environment). manufacturer manual p. 4 Frequency of Starts: excessive cycling damages control components, splines, bearings and windings; run motors at least one minute; maximum starts per 24 h (300 for encapsulated motors up to 0.75 hp); p. 7 check valves hold pressure when the pump stops; VFD section: small tank, 10–20% of pump output per minute, max 200 starts/24 h. (How the tank works)
- (2000). SQ/SQE Stainless Steel Submersible Pumps (product brochure). Grundfos (distributor copy). manufacturer brochure SQE motor speed variable between 65% and 100%; the CU 301 controller holds a constant pressure from a pressure sensor; soft start with a 2-second ramp. Year approximate (c. 2000). (How the tank works)
- (2024). Water pump won't start, won't stop, or short cycles (diagnostic table 1 of 3). InspectApedia. reference website Pump will not shut off: water running, damaged pump cannot reach cut-off, cut-off set too high, clogged pressure-switch sensor port; a pump that does not turn off creates a dangerous over-pressure condition. Short cycling: waterlogged tank most common, too little precharge; very rapid cycling can be a clogged water filter or blockage on the pump's outlet side. Pump starts with no use: slow leak (running toilet), leaky check or foot valve. Year approximate (undated; newest reader note 2024; read 2026-11-10). (Why Your Well Pump Keeps Cycling)
- (2024). Diagnose and Repair Poor Water Pressure / Lost Well Water Pressure. InspectApedia. reference website Poor pressure from pump, tank or control-switch problems; low well yield; rust-clogged steel supply piping; small-diameter piping limits flow; a clogged water filter reduces pressure. Year approximate (undated; read 2026-11-10). (Why Your Well Pump Keeps Cycling)
- (2025). 4" Submersible Pumps Quick Guide, IM453 Rev 2. Xylem Inc.. manufacturer manual Check valve for every 200 ft of vertical pipe; some installers add one on the discharge even with a built-in valve; with a pitless adapter the top check valve should be below the pitless, not at the tank; with well seals or well pits it is allowable to locate the top check valve near the tank. Footer IM453_Rev 2_2025-07. (Why Your Well Pump Keeps Cycling)
- (2021). You and Your Well (PUB-DG-002). Wisconsin DNR, Drinking and Groundwater program. state guidance In Wisconsin only persons with a current pump installer license may install and replace pumps, pitless adapters, piping and pressure tanks. Year approximate (no date printed). (Why Your Well Pump Keeps Cycling)
- (2011). Pumptrol Water Pump and Air Compressor Pressure Switches (catalog pages, Class 9013 Type FSG). Schneider Electric. manufacturer catalog Standard settings 20/40, 30/50, 40/60 psig; FSG2 cut-in range 20–65 psig, adjustable differential about 15–30 psig; 'Differential: the difference between cut-in and cut-out pressure'; low-pressure cut-off option opens at about 10 psig below cut-in to stop the pump if it runs dry or a line breaks. (Why Your Well Pump Keeps Cycling)
- (2007). How do you adjust the settings on a 9013FSG switch? (FAQ FA121330). Schneider Electric. manufacturer FAQ The large range nut sets cut-in (and moves cut-out with it); the small differential nut sets cut-out only. Published 2007, modified 2026. (Why Your Well Pump Keeps Cycling)