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 This article explains 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 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 WATER 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. We 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.
Watch Out: 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 & REPAIR and WATER TANK REPAIRS.
If the Water Pump Is Not Turning OFF
If your well pump won't stop running, you should probably turn it off to avoid burning up the pump motor. Causes of continued pump operation include lost water supply in the well, well piping leaks, well pump defects, or an improperly-adjusted pressure control switch that has called for higher water pressure than the pump can achieve.
If the water pump will not turn OFF, see WATER PUMP WONT STOP RUNNING
Water Pump Won't Start - If the Water Pump is Not Turning ON Try These Steps:
If your well pump won't start, you should have already determined that you have electrical power at the pump if you followed WATER PRESSURE LOSS DIAGNOSIS & REPAIR 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 about 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.
Watch out: The same sediment that clogs pump control switches also clogs water pressure gauges.
So your gauge could be wrong. (You can purchase or make a water pressure test gauge that connects to a hose faucet anywhere in the system if you want to double check for this problem.) |
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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.
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- 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 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.
Try the Pressure Control Switch Bypass Lever - if you have one
 Some pressure control switches include a metal lever along one side of the switch. Lifting this lever from its horizontal (off) position upwards towards vertical (on) position, will "force" the pump switch to turn the water pump on.
In our pump control drawing (left) the red arrow points to a pump pressure control switch bypass lever. Most pump pressure control switches do NOT have this feature, however.
Provided that you also have electrical power at the switch, the well pump should turn on if you lift this lever. Some manufacturers such as Square-D call this the "Maintained Manual Cut-in Lever or Manual Cut Out Lever" (depending on the switch model and application). "Manual cut in" means that lifting the lever will turn on the pump.
Watch out: Do not leave the manual cut-in switch on (up). Turn the switch back off and proceed to diagnose why the switch was not turning the well pump on and off automatically.
Check the pump pressure control switch for pressure sensor clogging
 If your well water is high in iron, sediment, or minerals, we 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. Other pressure control switches may be bolted right to the pump motor and may use a flexible plastic or copper tube to transmit water pressure to the switch.
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 our 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.
Check for Problems with the Tubing Connecting the Pressure Switch to the Water Piping or Water Tank
 Debris can clog the tubing connecting (or mounting) the pressure control switch to the water tank or water piping, preventing the pressure switch from responding properly to changes in water pressure. The result may be intermittent failure of the switch to turn the pump on or off, or it may result in a hard failure to turn the pump on or off.
Our photo (left) shows a copper tube running from a two-line jet pump (photo center) to the bottom of a pressure control switch (the gray box at lower left). This is the tube that carries water pressure (pressurizing air in the tubing) to the bottom of the pressure control switch.
Pressure Control Switch Tubing Clogging
Clogging of the Water Pump Pressure Control Switch if your water has a high level of silt, debris, or minerals, it's possible
that the tubing or piping connecting the pump pressure switch to the pump or water piping, or the pump switch bottom orifice through which the pressure switch senses the water pressure in the system has become clogged.
The small diameter of this tubing and still smaller diameter of the pump switch orifice makes clogging easy if your well water is high in sediment or minerals.
A clogged water pump pressure control switch will often fail to turn on the well pump at all, even though the pressure in the system has dropped
below the water pump "cut in" pressure. Reader Jeff Crosby reported an example of this pressure switch clog problem:
[When our well pump kept short cycling and I was unable to get the well pump pressure control switch to work properly, ...] I ended up calling the pump service company to come over. There was an extreme amount of mineral buildup inside the pump where the copper tubing initially comes out to travel to the pressure switch. I thought about checking that out but did not know how funny. There has always been an awl sitting on the pump base for the longest time. One of their maintenance guys left it there long ago. Now I know why - ever since that date when they come do their yearly check up they knock out this sediment [using the awl to open the tubing so that the pressure switch can accurately sense the water pressure in the system]. -- Jeff Crosby
On rare occasions we can tap on the well pump control switch and it will begin
working again, but not for long, and not reliably. Another water pressure control switch failure is the
rupture of a rubber disk or "bladder" inside the switch itself. If you detect or suspect a defective pressure
control switch, try replacing it with a new one.
We see a similar problem affecting water pressure gauges on private water systems: debris or mineral deposits can clog the pressure sensing orifice on the water pressure gauge, causing it to fail to respond at all, or to respond inaccurately to changes in water pressure.
When we find a clogged water pump pressure switch or the tubing connected to it, or a clogged water pressure gauge, we replace those items. A well pump pressure gauge that does not respond to pressure changes is potentially unsafe as it could lead to excessive pressurization of the water tank and building piping.
Pressure Control Switch Tubing Leaks
Thanks to reader Bob Hartman-Berrier for explaining a more subtle problem with pressure control switch tubing - wrong (too-small) diameter, causing a leaky fitting, preventing the pressure control switch from properly responding to changes in water pressure.
The tubing connecting a pressure switch may be steel (a rigid small-diameter mounting pipe), flexible copper (connected with flare fittings), or flexible plastic (connected using special brass connectors. Changing the tubing, especially plastic tubing, can get cause trouble.
Mr. Hartman-Berrier diagnosed this problem by observing that the pressure control switch would turn the water pump on if the override lever on the pressure switch were moved to the "on" position, but otherwise the switch did not work. The pressure switch was not turning on the water pump even though the water pressure was below the "cut-in" pressure setting. Because the pressure control switch was a new one, investigation eventually turned to a possible problem with the plastic tubing connecting the switch to the water tank.
... the pump would not come on by itself but it would come on if I used that over-ride switch. The replacement tubing between the pump pressure sensing diaphragm and the pump body was not small enough on its inside diameter to make a tight seal on the nipples of the switch and the pump body. The seal was tight, but not tight enough; the hose didn't blow off, but it wouldn't allow the pressure to build up in the tube and on the pressure sensor.
For a proper fit and thus for the pump pressure switch to sense the water pressure in the plumbing system, the internal diameter of the pressure tube must match the fittings to which it attaches. I was worried about the outside diameter, thinking the inside dimensions of the new tube would be the same as the old one. It wasn't.
I was also worried about "priming" the pressure sensing tube and the pressure switch diaphragm, thinking that because any air in the tube is compressible and that the diaphragm wouldn't be activated because the air would keep compressing. This was a mistake. The volume of air at higher pressure will be reduced, but the air pressure and water pressure will always be the same. [Boyles law - see WATER TANK PRESSURE CALCULATIONS]. I changed the hose (more-or-less proper ID), plugged in the pump and - miracle of miracles - the switch turned on. Its been running fine since then, and we've had plenty of water and pressure.
Watch out: your water pump might have two tubes running from the pump body: one tube carrying pressure to the pressure control switch, and a second, similar-diameter tube that is connected between the pump body and an air volume control. AVCs are discussed at WATER TANK AIR VOLUME CONTROLS.
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 we have to take the switch off to diagnose it anyway, if on removing and inspecting the pump pressure switch we think it was clogged, I’ll often just replace it.
How to Check & Clean the Well Pump Switch Contacts
 Check the water pump pressure control switch for dirty, burned contact points:
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 we 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.
We 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 PUMP PRESSURE CONTROL REPLACE for reinstalling the control.
Watch out: do NOT try working on a pump control switch without first removing electrical power - you could be killed by electrical shock.
Causes of burned pump pressure control switch contact point surfaces include:
- Old switch, long usage
- History of pump short-cycling on and off too frequently WATER PUMP SHORT CYCLING
- Switch installed in a wet location or one where corrosive gases are present (pool chlorine)
- Prior attempts to "clean" the points surfaces by filing or sanding (works only temporarily)
If the pressure control contact point surfaces are burned, it may interfere with the pump turning on. While it is possible to clean or even file these surfaces to get the switch working again as an emergency temporary fix, the switch needs to be replaced. While we have heard a report of the pump pressure control switch failing to turn "off" blamed on burned contact points, we think that when a pump won't turn off other causes are more likely.
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 PUMP PRESSURE CONTROL REPLACE
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The Home Reference Book - the Encyclopedia of Homes
