Preasurized well tank location

[John Gratton]

I have a 10,000 gallon catchment tank located about 150 ft from a 1 hp shallow well jet pump. The pump has an attached pressure switch.

It's all new construction.

I wanted the preasure tank for the system mounted about 30 ft from the pump but when the plumber tried this configuration the pump wouldn't shut off when it reached preasure. The pressure gauge at the pump showed wild fluctuations of pressure, so it seemed the pump kept seeing a brief low pressure and switching back on for just a short burst, then switching off, then on... To fix this this the plumber moved the pressure tank under the deck next to the pump. That took care of the pump not shutting off, but now I have to get a smaller tank that will fit in the space where the pump is located.

My question is, is there something that can be put between the pump and the tank to keep these pressure fluctuations from getting back to the pump? Is this water hammer? Would an inline water hammer suppression device take care of the problem?

It seems to me these tanks are meant to be placed far from the pump. Take the case of a regular well, the pump is down a big hole, maybe 300 ft from the tank.

Thanks in advance for any help...

 

[RS]

I have seen this happen, and there are a couple of solutions. The best one is to move the pressure switch to be very close to the pressure tank, the other is to install a small pressure tank next to the pump. My understanding of what is happening is the water in the line is moving rapidly, so when the pump shuts off there is a rapid decrease in pressure at the pump, so it starts again. An inline water hammer suppression device would have to be quite large to solve the problem.

 

[Diehard]

Well hopefully @Valveman will stop by and chime in.

Out of curiosity, what is the pump cut-in pressure and the pressure tank bladder pressure?

 

[John Gratton]

30 and 50 psi

 

[Diehard]

50 psi?
I'm not asking the cut-in/cut-out pressure.
I was asking the cut-in and the air pressure that was set for the tank without any water pressure influence.

"The pressure in the pressure tank should be 2 psi less than the cut-in pressure for the pump. For example, if the pump cut-in pressure is 30 psi, the tank bladder pressure should be 28 psi. "

 

[John Gratton]

Oops, sorry.

I dont know how the plumber set up the tank, pressure wise. They did mess with it for quit a while before they moved the tank, so I can assume they tried different pressures.

 

[Diehard]

If it was, by chance, set at 50 psi air pressure, I'm sure the pumps pressure switch wouldn't like that.
If that was the case, I could see you having the problems you described.

 

[Valveman]

Like Diehard says, you need the correct air charge in the tank and the pressure switch needs to stay close to the tank. 30 to 50 pressure fluctuations are just how an old pressure tank system works. Adding a Cycle Stop Valve would make the pressure stay at a strong constant 40 PSI anytime you are using water. Also with a CSV a 4.5 gallon size tank is all that is needed. The small tank saves space, money, and makes the constant pressure happen quicker. A constant 40 PSI is so much stronger shower pressure than an average 40 when cycling 30/50 all the time that you won't even need soap in the shower.