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How to set the pump pressure control switch:
Starting here with advice about correct problem diagnosis of water pressure problems, this article series describes how to adjust building water pressure by setting the water pump cut-in and cut-out
pressure on the well water pump pressure control switch.
In brief tutorials we explain how to set and adjust a typical pump pressure control switch, how to make sure that the system is safe, and what water pressure settings to use.
We also point to our article on how to adjust building municipal or community
water pressure at a building.
We also provide a MASTER INDEX to this topic, or you can try the page top or bottom SEARCH BOX as a quick way to find information you need.
Water Well Pump Pressure Control Switch Adjustment: how to set the water pump cut-in and cut-out pressures
Here we are discussing setting the water pressures at which a water pump will turn on (to get more water) and off (to stop pumping water from the water source into the water tank).
Water pumps use a pressure control that specifies the pump cut-in (turn on) and cut-out (turn off) water pressures.
[Click to enlarge any image]
Watch out: SAFETY WARNING OF FATAL SHOCK HAZARD: if you remove the cover of the pump pressure control switch you can get access to the
two nuts that adjust the operating pressures of the water pump.
But watch out! There are also live electrical contacts exposed in this
area. If you touch them, especially being near water piping, there is a serious risk of death by electrocution.
Watch what you touch, or have
a professional plumber or electrician do this job for you.
Watch out: Pump pressure control switch adjustments are summarized inside the cover of many pressure switches, as shown in our photo at left.
Complete details of what these adjustment nuts do and which way to turn them are found
First Diagnose the Water Pump Problem Correctly Before Messing With the Pressure Switch Control Nut Settings
But before messing with the pressure control switch an accurate diagnosis of what's wrong might be useful.
If the water pump apparent "short cycle" is say 1-3 minutes this may be all your system can provide.
If however something has changed, and the pump used to run longer, say 2-5 minutes,
I suspect loss of air in the pressure tank or an internal problem in the tank (like a hole in the bladder if it's a "captive air" pressure tank).
The problem of lost air in the water pressure tank along with how to correct that condition are discussed
If the "short cycle" is very short, clicking on and off, there could be a different problem with the pump control pressure switch or with a dirty,
clogged water filter if one is installed on the system.
Dirty water filters as a source of rapid pump on-off cycling
If you want to set up the cut-out pressure on your pump control, while leaving the "cut-in" down where it is, you'll also get a longer "off" cycle, but if you set the cut-out pressure too high, the pump will just run forever since it can't reach that high pressure. This is easy to figure out since if you set it too high the pump will just keep running.
(Then turn it off electrically and set the cutout pressure a bit lower.) [This adjustment is only available on pressure control switches that have two adjustment nuts: Range and Differential]. Details are
In sum, it might be possible to improve this condition by adjusting the pump control which sets the cut-in water pressure (to start the water pump)
and the cut-out water pressure (to stop the pump).
Usually this isn't going to help with pump short cycling but adjusting the water pump can give a longer on-cycle for the pump and it can increase the water system pressure up to a point.
If you ask the pump for more pressure than it
can deliver it will simply keep running without ever reaching the cut-out pressure you've specified.
If your pump short-cycling behavior has
recently gotten worse, don't try to fix it by adjusting the pump pressures, go on to look at other problems like loss of the air charge
in the water tank or a defective or clogged pump control or water filter.
The article links below explain exactly how to set the water pump pressure switch, where the adjustments are located (the large and small nut found under the switch cover), which way to turn the nuts to increase or decrease the pump cut-in and cut-out pressures, and other pressure switch troubleshooting and repair procedures.
Continue reading at PRESSURE SWITCH NUT ADJUSTMENTS for details about which nut to turn in which direction in a pump pressure control switch, or select a topic from closely-related articles below, or see our complete INDEX to RELATED ARTICLES below.
Thank you to Jason Gapco at Education Solutions for careful editing and text suggestions, 12/2008
Thank you to Steven Prior, a reader, for questions leading to our clarification of the function of the large and small pump pressure control switch springs, and for his photograph of the pump switch springs, 3/23/2009
Thanks to reader Rise for pointing out that turning a nut clockwise means "to the right" or to the "more tight" position in the convention of how most threaded devices work. Nov 2009.
Thanks to reader Don Travis for discussing water pump adjustment details - July 2010
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