Well pump short cycling

**Eilselc** · 04-21-2011, 05:58 AM

Hello, I have a well pump that has started short cycling. I have a Flotec 42 gallon pressure tank that is three years old. I have removed it to check for it being waterlogged and does not seem to be. I have checked the tank pre charge and have it set to 2 psi less than the cut in pressure. Checked it several times since and it always remains constant. I have replaced the pressure switch and it still short cycles. BTW I have a 2 drop jet pump. I am guessing the well is about 90'. The pressure gauge on the pump never drops unless a faucet is opened and doesn't seem to loose prime- by that I mean the water supply is always constant and immediate and never spurts. I have played around with the pressure switch to get it to not short cycle as much, but if the shower is used, the pump will never shut off unless water usage is halted. My guess is my problem is down in the well, i.e. the foot valve. Am I on the right track? Any help would be greatly appreciated.

**valveman** · 04-21-2011, 07:15 AM

You say the system does not lose pressure unless someone turns on a faucet, so your foot valve is OK. The tank is holding the air charge so it is OK. Then you say when the shower is used, the pump never shuts until water usage is halted. Which means your pump is running continuously instead of cycling on and off, which is a good thing. I guess I don’t see where you think the pump is short cycling. Is it just bouncing on and off quickly when the pump starts or something?

**Eilselc** · 04-21-2011, 09:21 AM

Yes, the pump would kick on and off extremely rapidly and would not stop. Since playing around with the differential adjustment on the pressure switch, I got it to where it will now only cycle on and off rapidly about 3 or four times and then shut off. Half a turn either way now, the pump will just short cycle really fast or the other way not turn off at all. Hope this helps.

**valveman** · 04-21-2011, 10:00 AM

I am guessing the pressure switch is mounted on the side of the pump/motor, and you have a check valve between the pump and tank. If that is the case, remove the check valve and the bouncing will go away. Then you will probably find out that the footvalve is leaking, which is probably the root cause of the problem.

**DonL** · 04-21-2011, 10:20 AM

Sounds like a regulator problem, or plugged line going to the switch.

A bad foot valve would let water go back into the well, You would see the pressure drop when using no water.

I believe that a check valve between the pump and tank, It would have always done that, Not just started.

Just my thought.

DonL.

"Theory only works in a vacuum" , there are just to many unknown variables in every day life.

**Eilselc** · 04-21-2011, 11:27 AM

Yes the switch is mounted to the side of the pump. AFAIK, there is not a check valve. The outlet comes out of the pump and goes into a sediment filter. The filter is new and even in the bypass mode the bouncing still happens. Then goes into the softener and then pressure tank. Now that I think about it, I have a shutoff valve just after the pump and when I shut it off, the pressure still bounced. Thanks for the help, guess I need to replace a foot valve.

**valveman** · 04-21-2011, 12:03 PM

Originally Posted by Eilselc

The filter is new and even in the bypass mode the bouncing still happens. Then goes into the softener and then pressure tank.

I bet if you move the sensing line to the pressure switch from the pump to the pressure tank, the bouncing will go away.

**Eilselc** · 04-21-2011, 12:25 PM

Sure I will try that. Thanks for the advise. Why do you think this happened, problem did start a couple of weeks after I installed the sediment filter which was about a month ago?

**valveman** · 04-21-2011, 12:47 PM

Adding the filter made the pressure switch further away from the tank and added more restriction between the two. The pressure switch should always be right at the inlet to the pressure tank.

**Eilselc** · 04-21-2011, 01:41 PM

Will do, thanks again!

**LLigetfa** · 04-22-2011, 08:46 AM

Valveman pegged it. There is a strong enough pulse to trip the switch. Square D makes switches with a pulastion plug or you could try relocating it. You could also install a second filter in parallel to reduce the in-line resistance. A small bladder tank between the pump and the filter would absorb the pulse too.

http://static.schneider-electric.us/...9013HO0801.pdf