Pressure switch not turning on at 40PSI

[KineticoUser]

Ever since the pipe to one of my pressure tanks broke (and I fixed it), I find that my pressure drops to 45PSI and then stays there till it immediately drops to 15PSI for 8 seconds before the pressure pump kicks in. I checked my tanks and they are charged to 38PSI drained. My cutoff for my pressure switch works at 60PSI. This results in a few seconds of cold water in the shower every time this happens. I wonder if adjusting nut #2 up by 10PSI on my Square D switch and then lowering nut #1 by 10PSI might fix this problem. Before I do this, I thought I'd run it by the experts. What are your thoughts on this?

 

[LLigetfa]

I checked my tanks and they are charged to 38PSI drained.

Probably either your water or your air gauge is reading wrong and the two are not calibrated. If it goes immediately from 45 to 15, then there is probably too much air in the tank. Then again the gauge could be off as it should drop to zero if the tank is empty.

If the nipple to the switch is plugged or there is mineral buildup under the diaphragm of the switch, those too, could manifest the same symptom.

The 8 second delay is excessive and suggests a secondary problem. Is it a jet pump or submersible?

 

[Sponsor]

 

[KineticoUser]

It is a F&W CJ101B201 Centrifugal Pump
The pump works steadily to pressurize the tanks, and the tank pressure drops steadily, though it does seem to hang up at 45PSI a bit longer than at any other point. It is an immediate drop at that point, not a gradual one. I can manually depress the switch to engage the contacts, and the pressure pump goes on immediately. How do I check the nipple and diaphragm?
It doesn't drop to zero as there is water pressure from all the water in the pipes in the attic, and the storage tank is above the house, so there is gravity feed from there.

 

[Reach4]

When the pressure gauge reads 50 PSI (or some other pressure greater than 48, that you specify), what does the air precharge pressure read?

 

[LLigetfa]

If you describe or post a picture of how the switch connects to the water supply, then we could better advise. If it is a rigid threaded nipple, then you would need to remove the wires and unscrew the pipe threads. I have found that disassembling the switch diaphragm usually damages it so unless you have a rebuild kit on hand, you might be making an emergency run to the hardware store to pick up a new switch. IMHO they are inexpensive enough to just replace it if it is old and cruddy. If the inside of the nipple is cruddy then there is a good chance the switch is too.

 

[LLigetfa]

the storage tank is above the house, so there is gravity feed from there.

Is the storage tank separate from the pressure tank? The pressure switch should be near the pressure tank.

 

[KineticoUser]

OK, something's not right. The precharge pressure reads 49PSI. The inside header gauge reads 59PSI. The outside faucet reads 51PSI.

That's using 3 different instruments to read 3 different locations.

 

[KineticoUser]

I have a 10K gallon gravity feed storage tank. The pressure switch is on the pipe between the pressure pump and the pressure tanks. The pressure switch is threaded, so I can unscrew it, but not till Saturday. It's not that old, and it looks good from the outside.

Maybe I should adjust nut #1 until the faucet pressure is higher. Actually, I had the inside pressure reading 75PSI, but I lowered it to 60PSI. The delay appears to be longer at 60PSI. What if I set it so the outside faucet reads 70PSI?

 

[Reach4]

Probably either your water or your air gauge is reading wrong and the two are not calibrated.

OK, something's not right. The precharge pressure reads 49PSI. The inside header gauge reads 59PSI. The outside faucet reads 51PSI.

When the pump is off and the pressure is at an intermediate pressure, all 3 should read about the same. Yes, there is a difference due to altitude differences of 0.434 psi per foot, and there could be a slight effect from diaphragm tension, most of that difference will be calibration difference.

So you will want to take that into account in setting things up.

Your tire store could probably check the calibration of your tire pressure gauge for you.

 

[KineticoUser]

Based on the altitude difference, the higher gauge on the inside header should be no more than 1.5PSI less than the pressure tanks and 3PSI less than the faucet. I just bought 2 new faucet gauges, and they both read the same, so that is the reading I'd trust the most. There is about a 1.5PSI increase from the higher pressure tanks to the lower faucet, so those make sense. If I adjust the pressure to the outdoor faucet, what would be the ideal reading? Square D says: "NOTICE: The switch should never be adjusted to cut-on below 20 PSI, or cut-off above 60 PSI."

 

[LLigetfa]

If you have been changing the settings then you might have got turned around as to which nut does what, inadvertently lowering the cut-in. Try turning the nut on the big spring in a few turns to raise the cut-in. Note that it also raises the cut-out. The small spring affects only the cut-out.

 

[KineticoUser]

I raised the outside faucet pressure to 60PSI. Now, the inside gauge reads 68PSI.
I've only been turning nut #1, which is the larger spring.

 

[LLigetfa]

I've only been turning nut #1, which is the larger spring.

So then, does raising the cut-out also raise the cut-in? If you don't want to raise the cut-out any higher then turn the nut on the small spring out a turn for every turn you make on the big spring.

 

[KineticoUser]

I'll see how it works when I take a shower tomorrow. If it still has a problem, I'll increase the large spring nut and decrease the small spring nut. I won't be able to do it till Saturday, so I'll get back to you with the results.

 

[Reach4]

So then, does raising the cut-out also raise the cut-in? If you don't want to raise the cut-out any higher then turn the nut on the small spring out a turn for every turn you make on the big spring.

I did not try to compute the corrections, but you should compute the gauge offsets, and set your air precharge to 2 PSI below your cut-on. Remember to always have near zero water pressure ( well under the precharge anyway) when you set the precharge air.

 

[KineticoUser]

I believe you were correct. When I removed the switch, I discovered the nipple was pretty much completely sealed. I drilled it out and cleaned it up, and I thought that would be an easy repair. Unfortunately, when I tightened the nipple into the PVC fitting, I cracked the fitting, so I had to rebuild that part of my PVC line. I have it all put together, and have water in the system, but I want to let it set a bit more before pressurizing it. I think I'll order another switch, as I'm sure debris got into the diaphragm area. I expect this one will work till I replace it. Thanks for the insight. I'll get it all adjusted once the PVC cement completely sets and I pressurize the system.

 

[PumpMd]

A pressure switch should work freely by seeing if you can turn the pressure switch on and off manually on the metal plate under the springs or spring. When you can't work it freely with little effort, your going to have build up under the pressure switch and sometimes bad enough inside the pressure switch on it's diaphragm to not work properly when you Only take care of build up under the pressure switch.

So you don't completely wipe out your threads trying to unscrew the nipple completely with build up on the threads of the nipple. Remove the build up inside the nipple still in place and manually activate your pump to remove the build up you knocked off(Pressure and flow going out the nipple, so don't get your electrical items wet).

Putting to much torque on a plastic fitting will crack from top to bottom.

 

[KineticoUser]

No more cold blasts in the shower or significant reduction of pressure, and I won't even receive the new switch till today. I guess I'll store the new switch and put off replacing it till I see another problem. Thanks for your help.

 

[Valveman]

No more cold blasts in the shower or significant reduction of pressure,

With the pressure switch nipple cleaned out you should never see lower than 40 PSI when using a 40/60 switch. But the 40 PSI is a significant reduction in pressure from 60 PSI at pump shut off. You would have even stronger pressure in the shower and a steady temp from the water heater if you had 50 PSI constant, instead of the 40 to 60 over and over you see now. A constant 50 PSI in the shower gives much stronger pressure than when the pump is cycling on and off between 40 and 60.