How to Repair a Water Pump Pressure Control Switch
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Here we discuss inspecting, cleaning, and possibly repairing a typical Water Pump Pressure Control Switch, normally found mounted on piping at the water pressure tank such as in this example where you see a small gray-covered box with electrical wires coming in (power) and out (to pump) of it.

The details of how to remove and replace a well pump pressure control are at WATER PUMP PRESSURE CONTROL REPLACE for reinstalling the control.

The pump pressure control switch, by being connected to the actual water piping in the building, senses the water pressure and when necessary, turns the water pump on. The water pump pressure control switch either turns on the water pump directly, or (particularly when a submersible water pump is in use), this switch may operate a physically separate (usually wall-mounted) heavier-duty pump relay which turns on the water pump itself. See PUMP RELAY SWITCH for more details of that control.

If the water supply is high in sediment often sediment will clog the pressure sensing opening at the bottom of the pressure control. We've tried cleaning out this orifice but it's never proven to be a lasting repair. If your pump pressure switch stops responding to changes in water pressure it probably needs to be replaced.

How to Diagnose and Repair a Water Pump Pressure Control Switch that Sticks "on" or "off" or is misbehaving

If we’ve traced a pump control problem to the water tank or water pump pressure switch itself with some certainty, we will often just replace the switch. But beware, we once replaced a pump control switch when the problem was a clogged filter which was causing the pump to cycle on and off erratically. I felt pretty stupid.

How to Diagnose a Malfunctioning Water Pump Control Switch

 We’ll need to do some water pump switch diagnosis – here are a few ideas that may help getting a recalcitrant pump control switch working again.

Safety warning - Shock Hazards: To remove a pump control/pressure switch remember to turn off electrical power, and using a neon tester or VOM double check to make SURE that electrical power is off, and taped-off so that on one turns it on and causes you to get shocked. Working around electricity and plumbing is particularly dangerous because of the increased chance of touching a live electrical wire while touching grounded plumbing piping.

How to Check a Well Pump Pressure Control Switch for Normal Operation

A pump or water tank pressure control switch is designed and adjusted to turn the pump on at a "cut in" pressure, usually 20 psi or 30 psi, and to turn the water pump off at a "cut out" pressure, usually 40 psi or 50 psi. When you buy this control it is usually set at the proper cut-in and cut-out pressures - check the box.

If your pump control is properly adjusted (see WATER PUMP PRESSURE CONTROL ADJUSTMENT ) then it should be turning the pump on and off nicely at the pre-set pressures. If the switch is behaving erratically or not coming on or not shutting off at all, there could be various explanations, some of which have nothing to do with the switch itself. These other problems are discussed at WATER PRESSURE LOSS DIAGNOSIS GUIDE and WATER TANK REPAIRS.

If the water pump is not turning on

You've already determined that you have electrical power at the pump if you followed WATER PRESSURE LOSS DIAGNOSIS GUIDE and WATER TANK REPAIRS.

Look at the water pressure gauge reading.

• When pressure is below the water pump control cut-in pressure:
  
  In our water pressure gauge photo at left we show a pressure of abuot 17 psi. Since this is below our water pump cut-in pressure which was set to a little over 20 psi, the pump should have cut on. Something was wrong.
  
  If the water tank pressure gauge reads a low number, say below the pump's cut-in pressure, try tapping the gauge gently to see if the indicator needle moves.
  
  The same sediment that clogs pump control switches clogs water pressure gauges.
  
  
  
  
  
  
  
• When the water tank pressure gauge reading is above the water pump's "cut-in" pressure (say 32 psi as we show in the photo at left), don't expect the pump to turn on. In that case, run some water in the building, watch the gauge pressure fall to below the pump's cut-in pressure, and then we should hear the pump turn on.
  
  
• If the water pump is in the well (a submersible well pump) you won't hear it running, but you can hear the pump relay click in and out (close or open) and you can see the water pressure change at the gauge when the water pump is running.
  
  
• If the pump runs and water pressure is present in the building but the water pressure gauge pressure never changes, it's probably the water pressure gauge that needs replacement. You can replace a water pressure gauge following the same procedures we outlined at WATER PUMP PRESSURE CONTROL REPLACE.

Tap on the water pressure control switch

If the water pressure gauge stays low (below the pump; cut-in pressure, try tapping on the side of the pressure control switch housing itself. Don't bang it with a hammer, just tap it.

If the pressure control relay switch closes and turns on the pump after you tap on it but if it otherwise sometimes "sticks" in the "off" , there's probably a problem with the pressure control. It could be a dirty or burned electrical contact, a loose electrical connection, or debris clogging the diaphragm of the pressure sensor (or something else we haven't thought of).

Tap on the water pump itself

If the pump is accessible we might give it a smart rap with a small wrench. Don't bang it with a hammer. Just as a connection in a pressure switch may be loose or dirty or bad, the same could be true of a pump motor. If tapping on the water pump makes it start, it needs repair or replacement.

Check the pump pressure control switch for clogging:

If your well water is high in iron, sediment, or minerals, I find that sometimes the small diameter pipe that mounts the pressure control switch onto the water line, water pump, or water tank will clog with these materials. In the photo at left I'm pointing to the pressure control switch. You can see the small diameter mounting pipe that connects the bottom of this pressure switch to the building water supply piping right at the bottom of the water tank.

If this pipe (usually ¼” or 1/8” IPT diameter) is clogged with debris, you might be successful in getting the pressure control switch working again by removing the control switch, confirming that the line is packed with debris, and replacing it.

BUT

In  my experience often when there is enough debris to clog the pressure control switch mounting pipe then the same debris also clogs the still smaller opening in the bottom of the pressure switch itself. It’s this small opening that permits water to press against a diaphragm in the bottom of the pressure switch and thus allows the switch to sense the water pressure.

How to Check the Bottom of the Pump Control Switch for Clogging

If as long as we’re taking the switch off to check these things I’d check out that opening on the switch bottom as well. We do this by unscrewing the connecting pipe from the bottom of the pressure switch, and looking inside of the opening into which that pipe was connected.

In a pinch it’s good to know that you may be able to clean the water pump control switch right up and get it working again.

Be careful about poking anything into the threaded opening which connects the pressure switch to the water pump or water tank. It's tempting to just jam a paper clip into the little sensor hole and wiggle it around. But if you puncture the switch diaphragm you'll certainly need a new switch. (You probably need one anyway if you see a lot of crud in there.)

It's possible to remove all of the phillips-head screws you see in this photo of the underside of a pump pressure control switch, to expose the diaphragm, and to clean out the whole mechanism. Don't tear the diaphragm

Since a new pressure switch is not very costly, and since I have to take the switch off to diagnose it anyway, if on removing and inspecting the pump pressure switch I think it was clogged, I’ll often just replace it.

How to Check & Clean the Well Pump Switch Contacts

 If the pump pressure control switch contacts are burned we can sometimes get it working again for a while by first, turning off electrical power as I described above, and then using a file, carefully cleaning all touching-surfaces the switch contacts.

A file may produce less grit and debris in the switch than sandpaper. I sometimes use fine sandpaper anyway, but in either case be careful not to leave grit and debris in the switch or it’ll fail again that much sooner.

If after inspecting the pump pressure control switch or its mounting fittings you decide that you've repaired it or that you need to replace it, follow the instructions at WATER PUMP PRESSURE CONTROL REPLACE for reinstalling the control.

A Guide to Building Water Pressure by Adjusting or Repairing the Water Pump Pressure Control Switch

• How to Adjust Water Pump Pressure: The detailed, step by step procedure for inspecting and adjusting the water pressure control switch is discussed in detail at ADJUST PUMP PRESSURE CONTROL.
• Diagnosing Water Pump Short Cycling on and off: If your water pump is clicking on and off too often or quite rapidly see SHORT CYCLING.
• Diagnosing & Repairing Lost Air in the Water Tank: The problem of lost air in the water pressure tank along with how to correct that condition are discussed beginning at SIGNS OF AIR LOSS.
• Diagnosing & Repairing a Water Pressure Control or Water Pump Control Switch: We discuss diagnosing and repairing a water pressure control switch that sticks "on" or "off" or simply won't operate, at water pump Pressure Switch Repairs.
• Replacing a Bad Water Pressure Control Switch is discussed step by step at WATER PUMP PRESSURE CONTROL REPLACE
• Replacing a Bad Water Pressure Control Switch is discussed step by step at WATER PUMP PRESSURE CONTROL REPLACE