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PLUMBING TOPICS WATER PUMPS, TANKS, TESTS, WELLS, REPAIRS WATER PRESSURE REGULATOR ADJUST WATER PRESSURE REPAIR GUIDE & COSTS Questions about lost water pressure Advice to a homeowner Adjusting Water Pump Pressure Control Right Repair to Pump & Tank? Well Pump & Tank Replacement Costs Reliability of Pump & Tank Repairs WATER PUMP PRIMING PROCEDURE WATER PRESSURE LOSS DIAGNOSIS GUIDE WATER PRESSURE & FLOW MEASUREMENT Water Pressure Intermittent No Water Pressure Well Tank relation to Water Pressure Shaking the Water Tank? Water Pressure Tank Problems Water Pressure Tank Diagnosis Water pressure Later Returns "on its own" Water pipe clog diagnosis Water pipe clog repair guide Making the "right" repair Typical Water Tank & Pump Prices WATER PUMPS & WELL TANKS WATER PUMP & TANK SAFETY WATER PUMP CONTROLS & SWITCHES IDENTIFY WELL PUMP TANK COMPONENTS MAIN WATER SHUTOFF VALVE WATER PUMP ELECTRICAL SWITCHES WATER PUMP PRESSURE CONTROL WATER PUMP PRESSURE CONTROL ADJUSTMENT WATER PUMP PRESSURE CONTROL REPAIR WATER PUMP PRESSURE CONTROL REPLACE WATER PRESSURE REGULATOR ADJUST WATER PUMP RELAY SWITCH WATER TANK AIR VOLUME CONTROLS TANK AIR INLET VALVE TANK AIR VALVE REPAIRS WATER TANK PRESSURE GAUGE WATER PRESSURE GAUGE ACCURACY WATER TANK DRAIN VALVE WATER TANK RELIEF VALVE CHECK VALVES WATER FILTERS WATER PUMP TYPES & LIFE EXPECTANCY WATER PUMP, ONE LINE JET PUMP, TWO LINE JET PUMP, SUBMERSIBLE PUMP, WATER PRESSURE BOOSTER PUMP & TANK REPAIRS & COSTS PUMP & TANK SAFETY WATER PUMP SHORT CYCLING SHORT CYCLING PUMP CAUSES WATER PUMP & WATER TANK REPAIRS WATER PRESSURE REPAIR GUIDE & COSTS WATER PRESSURE LOSS DIAGNOSIS GUIDE WATER PUMP PRESSURE CONTROL ADJUSTMENT WATER PUMP PRESSURE CONTROL REPAIR WATER PUMP PRIMING PROCEDURE WATER PUMP WONT STOP RUNNING WATER SUPPLY & DRAIN PIPING CLOGGED DRAIN DIAGNOSIS CLOGGED SUPPLY PIPING / Tankless Coil & Hot Water PIPING IN BUILDINGS SEWER GAS ODORS WATER PRESSURE LOSS DIAGNOSIS WATER TANK TYPES: WATER, OIL, EXPANSION, ALL CAPTIVE AIR BLADDER WATER TANKS STEEL WATER TANKS BIG WATER STORAGE TANKS OPEN WATER TANKS WATER TANK AIR, HOW TO ADD WATER TANK AIR VOLUME CONTROLS WATER TANK AIR ADD AT AIR VALVE WATER TANK AIR ADD BY DRAINING WATER TANK AIR HOW MUCH TO ADD WATER TANK AIR HOW OFTEN TO ADD WATER TANK BLADDERS & CAPTIVE AIR WATER TANK BLADDER PRESSURE ADJUSTMENT WATER TANK LIFE EXPECTANCY WATER TANK PRESSURE CALCULATIONS WATER TANK REPAIRS CONTROLS & SWITCHES on WATER TANKS INTERMITTENT CYCLING WATER PUMPS WATER PUMP SHORT CYCLING SHORT CYCLING DETECTION SHORT CYCLING CAUSES WATER TANK AIR LOSS SIGNS WATER TANK REPLACEMENT WATER TANK SIZE & VOLUME WATER TANKS HOW THEY WORK WATER SOFTENERS WATER TESTS, CONTAMINANTS, TREATMENT WELLS CISTERNS & SPRINGS WELL CLEARANCE DISTANCES WELL LIFE EXPECTANCY WELL PIPING CHECK VALVES WELL PIPING FOOT VALVES WELL PUMP PRIMING PROCEDURE WELL SHOCKING GUIDE WELL, PUMP, TANK LIFE EXPECTANCY WINTERIZE A BUILDING More Information InspectAPedia® Home & Site Map Air Conditioning & Heat Pumps Bookstore Electrical Environment Exteriors Heating Home Inspection Insulate Ventilate Interiors Mold Inspect/Test Plumbing Water Septic Roofing Structure Accuracy & Privacy Policies Contact Us |
This article describes how to select and use an air or water pressure gauge to obtain accurate pressure readings, and what causes inaccurate water tank pressure gauge readings. Readers should also see WATER TANK PRESSURE GAUGE where we discuss water pressure gauges and their repair or replacement. Readers concerned with water pumps, tanks, and wells themselves should see WATER PUMPS, TANKS, TESTS, WELLS, REPAIRS. The page top photo shows the author testing the air pressure in a Well-X-Trol bladder type well tank. © 2009 Daniel Friedman, All Rights Reserved. Information Accuracy & Bias Pledge is at below-left. Use links at the left of each page to navigate this document or to view other topics at this website. Green links show where you are in our document or website. How to Read Water Tank Pressure or any Pressure Gauge Accurately
For digital pressure gauges such as the one we demonstrate in photos on this page, gauge accuracy and our ability to read the pressure gauge accurately may not be a concern. Our photo at above left shows the water pressure gauge at the bottom of a water tank. The left hand pressure gauge is "stuck" at a high pressure, probably from rust or debris entering the gauge bottom port. Our photo at above right shows an identical gauge (same manufacturer) installed on the same water system, but located on the water pump itself. It is reading accurately.
But for dial-type pressure gauges or for "stick type" tire gauges (photos above left and right) use an indexed stick that protrudes from the gauge bottom. The accuracy with which a gauge reports and you can read pressure varies. We don't trust stick-type pressure gauges for accuracy. Dirt on the sliding indicator gauge, age, loss of lubricant, quality of manufacture (on some units, not all), and errors in reading the gauge all lead to errors, sometimes substantial errors.
Our photos just below show the author using a digital tire pressure gauge to measure the air pressure in a bladder-type water pressure tank or well tank.
Check the air pressure in the water tank by using an accurate air pressure gauge (such as a dial type or digital tire pressure gauge) to measure the air pressure at the schrader valve on the water tank. The tank pressure should be within 10% of the original factory water tank pressure setting. Our photo (above left) shows the water tank air inlet valve on the top of our Well-X-Trol well tank. We removed the cap and label for the photo. Our photos, below, show these same pressure gauges in use to measure air pressure in an automobile tire - a Mini Cooper run-flat tire that needs to be kept accurately at the proper air pressure. Be sure to press the gauge orifice down firmly and straight onto the air valve. Regardless of whether you are checking pressure in a vehicle tire or a home water system well tank, holding the gauge askew will cause air to be lost out of the pressurized container.
Causes of False Water Tank Pressure Gauge Readings - too high or too lowWhile normally water pressure gauges do a great job and are reasonably accurate, on a water tank a water pressure gauge can give very inaccurate pressure readings, especially if it's pressure intake port, a small diameter hole, or the small pipe on which it's mounted are debris clogged. If your water supply contains sediment or debris, or if the water is high in iron or mineral content, this blockage becomes more likely. False High Water Pressure IndicationsWater under pressure has entered the gauge at the high-end of the pump on cycle, but its exit is blocked or slowed by blocking debris at the gauge. So when actual water system pressure falls (water is drawn out of the system, pressure drops typically 20 psi before the pressure switch turns the pump back on), the gauge continues to read higher than actual pressure. False Low Water Pressure IndicationsThe system water pressure has fallen, perhaps to just below the pump cut-in pressure, and stays there long enough for the pressure gauge to slowly bleed its own higher pressure water out through a partly blocked opening. The indicated pressure on the gauge falls to some low level, in some cases even near zero. Additional water is drawn from the system, the pressure drops just enough more that the pressure control switch turns on the pump and system water pressure rises up to the cut-off or cut-out water pressure. But the gauge continues to read a false "low" because incoming water to its sensor port is blocked by debris. Note that these debris blockage conditions that cause false high or low water pressure indications on a water pressure gauge are the same conditions that can occur at a water pump pressure switch, causing it to misbehave as well. A water pressure gauge can also indicate incorrect pressure simply because the gauge is inaccurate (this is not precisely calibrated lab-grade equipment) or because the gauge has become damaged. Remedy - How to Correct A Water Pressure Gauge that Reads too High or Too LowThe well pump is turned off, pressure is drained from the system (you do not have to let all of the water out of the tank, just be prepared for a little spillage). Then the new water pressure gauge is prepared for installation (make sure the gauge bottom threads match those of the old unit being replaced as diameters vary from 1/4" to 1/2"). See WATER TANK PRESSURE GAUGE for details of how to repair or replace a water tank pressure gauge. ... Technical Reviewers & References
Use links just below or at the left of each page to navigate this document or to view other topics at this website. Green links show where you are in our document or website. PLUMBING TOPICS If You Need Help Diagnosing a Loss in Water Pressure or Other Pump & Well Problems See These GuidesWATER PRESSURE LOSS DIAGNOSIS GUIDE
Books & Articles on Building & Environmental Inspection, Testing, Diagnosis, & Repair
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PLUMBING TOPICS WATER PRESSURE REGULATOR ADJUST WATER PRESSURE REPAIR GUIDE & COSTS WATER PUMPS & WELL TANKS WATER TESTING WATER TREATMENT EQUIPMENT CHOICES WELLS CISTERNS & SPRINGS More Information InspectAPedia® Home & Site Map Air Conditioning & Heat Pumps Bookstore Electrical Environment Exteriors Heating Home Inspection Insulate Ventilate Interiors Mold Inspect/Test Plumbing Water Septic Roofing Structure Accuracy & Privacy Policies Contact Us |
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11/03/2009 - 04/18/1998 InspectAPedia.com/water/Pressure_Gauge_Accuracy.htm - © 2009 - 1988 Copyright Daniel Friedman All Rights Reserved - InspectAPedia® is a Registered U.S. Trademark