How to Trouble Shoot Jet Pumps
The following problems will cause your pump to fail:
Low or no water - Loss of prime meaning the pump and piping on the suction side are empty of water and they must be full of water before starting the pump.
Leaky suction pipe or poor plumbing - This will also cause your pump to lose prime and run dry
Bad check or foot valve - This problem will present itself as a pump that shuts-off when the switch reaches its high setting and the pressure gauge immediately starts to drop. The pump turns on again, and the whole process repeats itself. If this continues very long the pump will over-heat and the thermal protector will turn of the motor. Then you have to wait until the motor cools off before it will again start. If this condition is not corrected it can quickly damage a motor.
If the pump is allowed to Run dry for any extended peroid, your impeller and diffuser will melt.
When this occurs you pump will still turn on but you will get low or no pressure, low or no water. You will also likely have to replace the mechanical seal. Which is great for people like us who sell parts, but not good for you!
Bad check valve or foot valve -The pump will build pressure then shut off then start again in rapid cycles. The valve must be fixed immediately or your pump will burn up due to excessive heat buildup. The thermal overload protection will kick in but this is still very unhealthy for your pump.
Bad or punctured tank - The pump will build pressure then shut off then start again in rapid cycles. The thermal overload protection will kick in but this is still very unhealthy for your pump. Check the air valve located at the top of the tank, if any water is discharged your tank is bad and must be replaced ASAP.
New Pump Installation
Jet pumps, check valves and pressure tanks must always be installed together, within a couple of feet of each other.
Sometimes on new installations you will hear what's called "pump chatter" at the start of a cycle or at the end of a cycle. There is nothing wrong with the pump or the tank or the check valve. The major cause is likely in the plumbing. As a general rule the line size from the suction should be larger or the same size as the discharge pipe. You should never use less than 1" between the discharge of the pump and the pressure tank tee. If you must reduce, do it after this point.
Water hammer is the result of a water shock wave inside pipes. The water hammer causes the chatter. A common cure is to adjust the pressure switch (caution - disconnect all power before attempting to adjust pressure switch on pump). Also you must check the air pressure in the pressure tank. Use a tire gage. Look for the shrader valve located at the top of the tank. The pressure should read 2 PSI (pounds) less than the cut in pressure of your pump For example; If your pump is set for 20/40 PSI you must set the tank pre-charge at 18 PSI. If you want 30/50 PSI then your tank should measure 28 PSI. This pressure test must be done only when the tank is empty of water.
If this does not work you might try relocating the pressure switch sensing line away from the pump and closer to the pressure tank. What can sometimes happen, expecially with larger pumps, or to small size, the pump builds up pressure and causes the switch to rapidly shut on and off.
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Deepwell jet pump (50 feet depth) pumps
water but will not build pressure. Possible
you are not giving me all the information I need, however, here are some things to consider.
1. I assume this pump was working properly when it was first installed. All of the other observations are based on this premis. If it never worked properly, there are a number of engineering factors to consider such as proper deep well jet sizing, etc.
2. The most common problem with poor jet pump performance is a leak on the suction side. It any air gets into the suction side, the performance is significantly reduced. This might present itself as air bubbles in the output water.
3. You might have a plugged jet or impeller. If foreign material gets past the foot valve and into the suction line of the pump, it can lodge in the above mentioned areas and not allow the pump to build up pressure. If a jet pump injector becomes plugged the pump will not be able to produce more than 30-35 PSI.
3. A defective pressure switch can also be a possible factor in low pump performance, but this is more unlikely.
I hope this helps, it by no means inclusive, but it's a place to start.
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