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Topic: 4008 Water Pump Operation (Read 7 times) previous topic - next topic
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4008 Water Pump Operation
Yahoo Message Number: 151249
As suggested, I received answers directly from Pentair, which owns ShurFlo:

Question: Does the 4008 pump use any power at all when power is applied to it but it is not operating?
 Answer: The 4008 pump does not draw any power when the unit is energized and pressurized (fixtures closed), the pressure switch is in the off position in this situation.

Question: Is the 4008 pump fixed or variable speed?

Answer: The RPM of the motor changes depending on demand.

Based on the specification sheet for the pump, it can draw 2.8 to 7.5 amps, depending on demand, with pressures from 0 to 55 PSI

Kevin Lindsay Garden Grove CA 2000 Lazy Daze 30' IB
Kevin Lindsay
2000 Lazy Daze 30 IB
Re: 4008 Water Pump Operation
Reply #1 –
Yahoo Message Number: 151250
Thanks for posting the follow-up; the "rest of the story" is always useful to know, and the information gained adds to the database!

Joan
2003 TK has a new home
 
Re: 4008 Water Pump Operation
Reply #2 –
Yahoo Message Number: 151258
>>Question: Is the 4008 pump fixed or variable speed? Answer: The RPM of the motor changes depending on demand.
 If find the answer to this question a bit misleading even though in the strict sense it is true.
 The old Shurflo 5.7 gpm Variable Speed Pump was designed to provide a constant water pressure over a wide range of flow rates.  It had a pressure sensor (not a pressure switch) that measured the pressure at the outlet of the pump.  An electronics module varied the pump speed and tried to keep this pressure the same no matter what the demand for water.  It is a great idea.  There are larger commercial water pumps that work this way.  Unfortunately the Shurflo implementation of this concept left a lot to be desired.
 The Revolution 4008 pump is just a normal 12 volt water pump with a pressure switch that turns it on and off.  Shurflo has included a "bypass valve" to improve pump operation when there is limited water demand.  When you apply power to this type of pump it wants to run a full speed.  However, as the pressure in the plumbing system builds up, the speed of the pump will decrease and the pump will draw more electrical current.  This is a characteristic of all DC motors.  In that sense, the  pump runs at "variable speeds."  However, this is not the same "variable speed" as that of the older 5.7 gpm pump.  The "bypass valve" feature is an attempt to make the pump run in the "middle of its operating range"  and prevent it from continuous stop/start operation with limited water demand.

Doug Baker