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Pump is constantly cycling on and off at the pressure limits of 40 and 60psi, respectively , when the water is being used.

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Do you have a tank with a air bladder inside or do you have one with a air valve on the side?

I suspect you have a tank with an air valve. If that is the case, yours sounds like a classic case of "air bound". There is the possibility that you have a Blue tank with a air bladder inside trhat does not have a air valve on the side - but lets talk about the classic tank now.

Your pump is "short cycling" because there is very little air cushion at the top of your tank. What you need to do is get more air into your tank. Turn off your pump. Turn off the main water valve. Open the tank drain. Press in the (probably) black ball on the side of the air valve. Let the water all drain out. When the tank is empty, let go the black ball, close the tank drain, turn on the pump. When it stops, open the water main to the house.

Let me know what happens.


Posted on Sep 26, 2009


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Water pressure tank. Cycles on and off every few seconds with water running. How can I test to see if the float is good or bad to get the air the tank needs. Thanks

Hi Robert:
Since it's cycling every few seconds, I'd be looking for one of two problems, either the pressure switch, or lack of air in the tank.
There should be a pressure guage on the tank, and the pump should have a low pressure start and a high pressure stop.
I'm not familiar with the "float" that you're referring to.
I would shut off the power to the pump and close the valve from the tank to the outlet line. Then I'd drain the the tank so that I knew there was lots of air in it. Turn the pump power back on, and see what the pressure builds to when the shutoff occurs. Then open the outlet lne valve. The pressure will drop and ultimately the low pressure limit will happen and the pump will start.

As long as the triggering pressures are correct, and there is air in the tank, all should be good.
Modern tanks have a diaphragm that separates the water from the air. There may be an air fitting on these.
Old tanks don't, so the air can eventually be absorbed into the water, and you have to add more air. Some of these tanks had air fittings on the top.

Jun 19, 2015 | Plumbing

1 Answer

I have a Fimcoatv sprayer with a high flo gold series pump mod # 5275704 ..the pressure will rise to 40psi & then drop to 20psi & then back to 40, this cycle continues through out the spraying...

As it is a diaphragm pump some pressure fluctuation will be normal but that is likely to be more of an oscillation at the speed of the pump rather than a steady or slow cycling of pressure.
If it is important those oscillations are damped to provide a smooth noise-free pressure the design would include an accumulator.

If everything remains constant - a constant fluid intake and a constant spraying orifice and the pump running at a constant speed then the pressure would be constant and the motor would be consuming a constant current.
Clearly something is not constant. Something must be changing and cycling to cause the pressure fluctuations. I have a theory but am not in a position to test the theory myself - Inserting an ammeter in series with the motor in the electrical supply to the pump and monitoring the current drawn should show it fluctuating at the same time the pressure fluctuates. If the current falls as the pressure falls my theory is the pump intake is being restricted somehow and if the current rises as the pressure falls the pump is labouring due to outlet being restricted in some way or because there is a motor fault. It would be important to monitor the supply voltage at the pump at the same time to ensure it remains stable.

Jun 01, 2014 | Northern Tool Garden

1 Answer

I replaced old pump w/ Flotec 1/2HP FP4012 and replaced old pressure tank w new 35gal tank. Pump primed but cycles on-off every minute constantly even w/ no water turned on. Goes to 50PSI, loses pressure...

The water and therefore the pressure has to be going somewhere. If you are sure that there are no leaks in the house or outside, then the water is going back into the well. There is a check valve either in the suction line of the pump between the top of the well and the pump or down in the well.
If this check valve fails, it allows water to go the wrong way and back to the well. The result is that you lose pressure.
Secondly, you have to be sure that there are no air leaks between the top of the well and the inlet to the check valve. Leaks in that piping will make repriming difficult.
Write back with more and I'll try to help more.

Jan 22, 2011 | Flotec Corrosion Resistant Shallow Well...

1 Answer

The motor keeps cycling on and off (about twice every second) when the pressure trigger is not operated. The unit seems to supply plenty of water pressure when trigger is operated.

The motor is holding pressure in the line.
Check the manual.
I don't think it is supposed to cycle that much.
If it's not designed to do that, then there is a seal or a bearing that is leaking.
It's letting water pressure escape the hose by letting water seep back into the pump.
The motor is pushing more pressure into the line to keep up with the internal leak.
Two times a second seems like a lot, and the noise is probably annoying.
If the unit is new, take it back.
If it's doing the job, run the equipment until it dies, or else take it for repairs.

We had a similar problem with a paint sprayer.
Paint sprayers also hold pressure on a line, except the fluid is paint instead of water.
When the machine sensed a loss of pressure, it would cycle once to restore pressure.
After a while it was cycling constantly, just like your machine.
Working indoors with the constant noise was a nuisance.
I had the machine rebuilt, and used it for another year before buying a heavier machine.
I don't know if there is a business that rebuilds your equipment, or how hard parts are to find.

Oct 27, 2010 | Karcher K2.26 Electric Power Washer

2 Answers

The pump goes on and off repeatedly

The pump should only run if you are using water. If you have a leak it will cycle on and off. If it only cycling fast when you're using water, you may need an expansion tank, sometimes referred to as a bladder tank for newer style. If you have a "bladder" tank , the bladder may be leaking and lost it's air charge. This bladder will have an initial air charge, and when the pump runs it will compress the bladder even further. When the pump shuts off the bladder is compressed. When you begin to use water, mainly low flow like one faucet, the bladder will begin to expand expelling the water from the tank until the pressure drops below that of the pump pressure switch. This makes the pump start and stop fewer times.

Jul 05, 2010 | Flotec Corrosion Resistant Shallow Well...

1 Answer

1/2 hp shall well pump. set at 30/50....seems to hesitate around 48 for an extra amount of time....have to shake the hose or tap the pressure plate to get pump to cycle off. also....noticed the pump...

50 PSI for a 1/2 HP pump is approaching the upper limit for that pump. Many things can affect the upper limit. How far the pump has to pull water up the well pipe, is there any air leak what so ever on the input. If the pump lost its prime because it could not attain the 50PSI, I would suspect it may be just outside the limits of the pump at this point in time. If this pump is on a shallow well, it may be that the shallow well point is beginning to plug and not allowing as much water in which would cause a harder pull for the pump. I would turn the high pressure side down to maybe 45 and see if it operates properly at that pressure.

I hope this helps.

Jun 22, 2010 | Flotec Corrosion Resistant Shallow Well...

1 Answer

Installed a new jet pump for shallow well (gravity feed to pump) - used old pressure tank - after about 4 months pump began kicking on and off constantly when in use - troubleshooting guide suggested it...

The pressure tank must have a certain amount of air in it so pump doesn't cycle as you say. The new pressure tanks have a bladder that separates air from water and keeps the pump from cycling so much. Make sure your pressure switch on the pump is OK--ie doesn't have burned contacts!

Mar 01, 2010 | Flotec Corrosion Resistant Shallow Well...

1 Answer

I have a propane hot water tank that in discharging the hot water out the relief valve (Champion energy saver series)

possible problems not knowing age of unit the
control valve could be sticking open allowing gas to continue to flow until high limit is reached and shuts down valve another possible problem with the newer style back flow preventer being install by water companys the rapid heating and expansion of the water over pressures the water system causing releif valve to pop open and reclose most water heater manufacters are recommending instalation of an expansion tank to allow the growth in volume of water somewhere to go is valve constantly leaking or only during heating cycle if you could supply additional information does unit only leak when heating
or is steam expelled when releif valve opens
t-stat not opening gas valve sticking partially open
bad high limit bad pressure releif valve no expansion tank to allow for thermal expansion if steam is present and unit is boiling water inside replacement of water heater for safety concerns,would be reccomended if only water and pops couple of times water temp not over 140 degrees after most hot water has been used out of tank and is reheating most of capacity probably lack of expansion tank as the releif valve is the final safety device on a water heater is of great concern
the temp control gas valve or high limit are supposed to shut unit done long before the safety limit of releif valve is reached

Dec 11, 2009 | Water Heaters

1 Answer

Gould 1/2hp submergible well pump cycles on and off constantly. low to no water pressure .The pressure switch remains in the closed position. Power to pump side of pressure switch good. pump runs 15...

My first thought was that of a water logged tank which causes short cycling, from your notes the tank is good (the tank may be partially water logged though) If the tank is ok and your getting short cycling (and the switch is good) I would guess your check valve down the well has failed. As the pump creates pressure then shuts off the water may be going right back down the well causing the pump to cycle again. This could also account for the poor water pressure as the check valve may be stuck slightly open allowing the system to loose pressure but only allowing a small amount of flow by when running. There could be a leak within the pumps drop-pipe and your loosing pressure through this leak. I expect you'll have to have the pump pulled.
I hope this may have helped,

Oct 10, 2009 | Plumbing

2 Answers

Need help

pump got nothing to do with water level only pressure sw vary it

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