Guide to Well Pump Tailpipes or Low Water Cutoffs
to Increase the
Life Expectancy of Well Pumps
WELL PIPING TAIL PIECE - CONTENTS: Definitions of well tail pipe or well tail piece for well pump damage prevention. Low water cutoff controls to protect well pumps from damage. Well drawdown control devices for pump protection. Water pressure regulators and smart tanks to protect well pumps from damage. Low flow well solutions - how to protect the water pump from damage by a low recovery rate water well. Factors affect the life expectancy and pressure ability of water pumps? How can we extend the life of a water pump, and how do we know when to replace the pump or pump controls?
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Well tailpieces for well pump protection:
Well Tailpipes or Tailpieces serve as Low Water Protection Devices.
This article describes the use of a tailpipe or tail piece, or other low water cutoff controls to protect a well pump from damage in a low-recovery rate well, thus extending the life expectancy of water pumps and pump controls.
What are the Best Low Water Cutoff Devices for Well Pump Protection?
How do we protect the well pump from damage if the well is subject to seasonal or permanent low flow rates or has a poor recovery rate? Here we explain the function & role of a tailpiece installed at the bottom of well piping in order to protect the pump and other water supply equipment controls from damage.
Low Well Water well pipe tailpieces or well tailpipes to protect the well pump
When the well pump's capacity is known to exceed the flow rate of the well, a tail pipe, tail piece, or low water cutoff control is installed to protect the pump from damage such as that caused by well pump cavitation or motor overheating.
Details: some wells that are known to have intermittent low water problems may be equipped with a special tailpiece on the water pick-up end of the well pipe precisely to prevent the well pump from becoming damaged when water level in the well drops too low. The red component in our sketch (left) is the ejector used by a two-line jet pump to bring water from the bottom of the well. This red component shows where a well flow protection tailpiece may be added - as an extension below.
A longer taipiece (blue in our sketch) extending into well water (30 inches recommended by the Alberta Canadia DOA) may help avoid air intrusion, but in addition, a special fitting at the in-water end of the tailpiece can cause water to recirculate through a well pump if well water level becomes too low. If the well pump is a submersible model (recommended for well depths over 80 feet), a similar low well water protection device may be installed in the well. In our sketch at left the foot valve is shown in yellow.
The well piping tailpiece (also shown in this sketch) permits the in-well water pump to continue to run by recirculating well water within the pump but by halting delivery of water or slowing delivery of water to the building.
Electrical Low Water Cutoff Devices to Protect the Well Pump
Many sources, including the Penn State School of Forest Resources recommend installing a low water cutoff device to protect a well pump that has to operate in an inadequate or low-yield well. That resource describes an electrical low-water cutoff switch:
Normally, a low-water cut-off switch
controlled by water-level sensors in the well should
be connected to a relay at the pump switch box. A
low-water signal relayed to the main switch should
override other pump controls and stop the pump if
the water level drops to a critically low point where
air or sediment would be pulled into the system.
A low water sensing device to protect a well pump may be installed in an intermediate water storage tank, for example.
A different approach to water pump protection where the well yield is poor is a tailpiece that is installed in the well itself. When the water level inside a well drops too low, the tailpiece re circulates water through the well pump (keeping the pump cool and protecting it from damage) until the well has recovered and the water level has risen.
Watch out: the low water cutoff devices that we discuss here are intended for building water supply piping to prevent well pump damage. These low water cutoff devices or switches are distinct from and have nothing to do with the heating or steam boiler low water cutoff safety devices discussed at LOW WATER CUTOFF VALVES
Water Pressure Regulation to Protect the Well Pump
A still different approach that may provide some water pump protection by reducing the well pump cycling rate is the installation of a Smart Tank that regulates water flow in the building. According to the manufacturer, Flexcon Industries,
Every Smart Tank
system includes a relief valve and a manifold that provides ports for the system’s
pressure switch, pressure gauge, drain valve and relief valve.The Smart Tank pressure system works just like a standard pressure tank system but
with one major difference - consistent water pressure delivery!
1.On demand, water is drawn from the Online pressure tank until the cut-in
pressure of the switch turns the pump on.
2.System water now flows through the regulating body of the Smart Tee
valve. The valve will maintain constant water pressure at each given flow rate, and
consistent water pressure over a broad range of flows.
3.When system demand ends, the Smart Tee’s calibrated bypass port keeps
the pump running just long enough to fill the tank and satisfy the cut-out setting of
the pressure switch. The pump shuts off, and the system is now ready for the next
The Smart Tank pressure system will reduce pump cycles
by as much as 75%, and give the homeowner the benefit of constant
water pressure. Fewer pump starts and longer run times means
longer pump and tank life.
Well Pump Cavitation Damage
Well pump cavitation describes the entry of air or gases into the mechanical parts that are trying to move water through a water pump. The presence of air or other gases in the actual pump chambers or around the water pump impellers leads to overheating of these parts and mechanical damage to the pump moving parts.
Cavitation can also cause the pump to have to work longer to satisfy the water demand and thus its electric motor to overheat, also reducing motor life.
Cavitation inside of a water pump can be caused by several problems including:
Inadequate well yield: if the yield of a well drops for any reason, trying to pump water beyond the safe yield of a well pump can introduce air into the well pump and water piping.
See WELL YIELD DEFINITION where we define safe well yield and discuss the importance of a proper match of the well pump capacity and its output rate to the well's safe yield. In that article you will
find how to DEFINE SAFE YIELD for a WELL
Oversized pumps that mis-match the well flow rate to the pump's output rate can also cause the pump to form a strong vacuum inside the pumping chamber around the pump impeller. The vacuum, in turn, causes dissolved gases in the water itself to leave solution and return to bubble form.
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Typical Shallow Well One Line Jet Pump Installation [ copy on file as /water/Jet_Pump_Grove_Elect_Jet_Pumps_1.pdf ] - , Grove Electric, G&G Electric & Plumbing, 1900 NE 78th St., Suite 101, Vancouver WA 98665 www.grovelectric.com - web search -7/15/2010 original source: http://www.groverelectric.com/howto/38_Typical%20Jet%20Pump%20Installation.pdf
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Water Fact Sheet #3, Using Low-Yielding Wells [ copy on file as /water/Low_Yield_Wells_Penn_State.pdf ] - , Penn State College of Agricultural Sciences, Cooperative Extension, School of Forest Resources, web search 07/24/2010, original source: http://pubs.cas.psu.edu/FreePubs/pdfs/XH0002.pdf
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