Pump cycles on at 10-psi (new here)

[Mr B]

I have an older pumptrol 20/40 pressure switch and a well-x-trol model wx 250 pressure tank. Every thing is working fine as far as water pressure, bath, toilet, sinks, etc but I was looking at the pressure gauge the other day and I notice that my tank will pump up to 40 psi and cycle off but it drops down to 10 psi before it cycles on.

I drained the water from the pressure tank and the tank pressure is at 19 psi. So I filled the tank back up with water and ran a faucet and the pressure dropped to 10-psi and the pressure switch cycled on, went to 40 psi and cycled off. So I ran the faucet and same thing off at 40 on at 10.

Can this be fixed and/or its not a big deal? I thought there should only be a 20 pound cycling difference between on/off.

Thank you

 

[Reach4]

You could get a new pressure switch. They are inexpensive. You could try adjusting the old one instead.

To raise or lower the cut-in and cut-out settings while keeping the
differential between those two settings constant, adjust the range
nut. The range nut is the 3/8-inch nut that adjusts the larger of
the two springs in Models FSG, FYG, FRG, and Type G Pumptrol
switches.
Turn the range nut clockwise to increase the cut-in pressure and
counter-clockwise to lower the cut-in pressure. Three and a half
revolutions of the range nut will change both the cut-in and
cut-out settings by approximately 10 psi.

Adjust the differential nut if you want to raise or lower the
cut-out setting while keeping the cut-in pressure constant. The
differential nut is the 3/8-inch nut that adjusts the smaller of
the two springs in Models FSG, FYG, FRG, and Type G switches. Turn
the differential nut clockwise to increase the cut-out pressure and
counter-clockwise to lower the cut-out pressure. Adjusting the
differential nut will change only the cut-out setting while the
cut-in setting remains unchanged.

You want to reduce the differential.
Maybe go 25/45 presuming the pump has no problem hitting shutoff.​

If you have a jet pump, set the air precharge to 3 or 4 PSI less than the cut-on to give the pump time to get going. Submersibles are faster, so 2 psi for them.

 

[Sponsor]

 

[Mr B]

I forgot to mention that it is a submersible pump down 280 feet. The cut out setting (40-psi) is fine it's just the cut in that can't be adjusted...from what I have been reading anyhow.

I just not sure if the 30 psi differential is a bad thing. I hate to change the pressure switch if it is not a problem with that much differential .

Also when the pressure switch reaches 10 psi it quickly (1 second) drops to zero and then the pump starts up.

Thank you Reach4 for the reply.

 

[Reach4]

I just not sure if the 30 psi differential is a bad thing. I hate to change the pressure switch if it is not a problem with that much differential .

It is a bad thing. It stretches the diaphragm more than it should.

Also when the pressure switch reaches 10 psi it quickly (1 second) drops to zero and then the pump starts up.

That means that your precharge is high. The only problem with a precharge that is high is the glitch in pressure that you are seeing.

 

[Mr B]

So lower it to 17 or 18?

 

[LLigetfa]

Replace the switch. they are not expensive and not worth repairing. I've tried taking one apart and the diaphragm disintegrated. You can buy rebuild kits but they are hard to find. What happens is that minerals build up under the diaphragm of the switch which prevents it from closing when it should.

 

[Mr B]

Thanks for the input LLigetfa. Sounds like I'll have a weekend project. Should I upgrade to a 40-60 psi?

 

[LLigetfa]

All of the switches are identical. It is just that the factory presets them to 20/40/ 30/50, 40/60. etc. You cant dial down a 40/60 to 20/40 if you desire.

That said, I would go for 40/60 if the tank is sized right for it. Higher pressure means less drawdown.

 

[Mr B]

Maybe I'll do a 30/50 just to be on the safe side. My pipes are 60 years old.

 

[Valveman]

It could also be the little nipple the pressure switch is screwed into is clogged. And if you really have 19 PSI air in the tank, the pressure should drop from 19 to zero instantly. Dropping from 10 to zero instantly makes me think you only have 10 PSI air in the tank. Might be your tire gauge is off.

 

[Mr B]

Thanks valveman, I did double check it with a dial gauge and a digital gauge and both read 19. The pressure switch is a very old square D with a metal cap and was in the house/basement since I bought it 23 years ago, for all I know it could be original. I had to use some solvent to get the 20/40 numbers off of it. Its an old system with a light switch and two fuses to turn the power off to the pump/switch.

 

[Valveman]

With the cover off the pressure switch, see if the points click closed when the pressure drops to 20 PSI, or if they do not close until 10 PSI. If they close at 20, but you have to wait for water to come, you may have a hole in the pipe or a bad check valve. But if it doesn't even click closed until it gets down to 10 PSI, either the pressure switch is bad of the nipple to the switch is clogged.

 

[Mr B]

I checked and they don't click closed until it reaches 10 psi and the system does hold pressure when not in use.

I was looking online and the big box store has 2 Square D's Model# FSG2J21BP and Model# FSG2J21CP both are 30/50 psi but I do not see the difference in the two except for the price. I cannot read any writing on my old box cover and there is no diagram on the inside of it....any ideas which one will work? Thanks

 

[Reach4]

CP stands for clamshell package, and is oddly sold cheaper than box/bulk version.

I think "BP= box" but that could be bulk packaging?

 

[VAWellDriller]

Pressure gauge on tank is bad and maybe a stopped up nipple on switch too.

 

[Mr B]

Thanks for the info guys. I'm going to buy the part tonight and install it on Sunday. I'll report back on the fix.

I was just looking at the wiring (4-wires) on the switch and there doesn't seem to be a green ground wire, that's weird. Unless it is hidden underneath the contacts.

 

[Mr B]

I bought a new pressure switch and the wiring diagram is opposite to my original switch. Mine has the pump wired to the two outside terminal and the power to the two inside terminals.

Should I go by the new diagram and wire the pump to the inside and power to the two outside terminals?

Thanks

 

[Valveman]

Doesn't matter.

 

[Boycedrilling]

The equipment grounding conductors may be green or bare copper. The are not switched by the pressure. They attach to the grounding screws at the base of the switch. Like vsovrmsn said, it really doesn't matter if the incoming power conductors are on the outside or inside set of screws. Just don't wire them both to one side of the switch. Seen that tried more than once, creates a dead short!

 

[Mr B]

Got it.....thanks guys.