Water Hammer When Pump Stops

[fotingo]

Hello,
I am in Florida on well water. The well head is about 80 feet from the house. The water tank and pressure switch are inside the car garage.
This house is from 1998, so I'm assuming the well is too. Ever since I bought this house, I notice every time the pump stops, it makes a loud noise and sounds like the pipes rattle in the walls.

I have been doing a lot of research, but based on what I've read so far, I am confused as to how to fix this.
Some say the check valve needs to be replace (which is located at the well head). I also read I may just need a water arrester installed after the water tank and before the sediment filter.

The last hurricane that past through here destroyed my well head (well, the PCV pipe that was connected to it). So, I had to redo the connection again.
I was actually going to replace the check valve, but I could not take that thing off at all. I put a lot of force to that thing and it didn't move! So, I left it alone and just redo the PVC connection that goes to the house.

I have no idea on the condition of the check valve. My question is, would a water arrester help with the hammer issue, and if so, what's the best location for it?

Thanks so much.

[Cary Austin]

Your pressure tank is a large hammer arrestor.  The problem is the check valve slamming closed from the full open position after filling the pressure tank.  Adding a Cycle Stop Valve has many benefits.  One of which is filling the pressure tank at only 1 GPM, not the full pump flow rate.  At 1 GPM the check valve is only open about the thickness of a piece of paper and there is no water hammer when it closes when the pump shuts off.

[fotingo]

As far as I know, this has been an issue. I replaced the water tank and the issue was still there. I have the water pressure at 35-55 and set the tank at 33 psi.
I check it every 6 months. I believe the tank is fine as I've never had any issues with it. It only loses 1-2 psi in 6 months.

Is that a picture of what you're suggesting? (the small grey tank)

[Cary Austin]

Water hammer will always be there when the pump is filling the tank at max pump flow of 10-20 GPM.  At 10-20 GPM the check valve is wide open when the pump shuts off.  The spring in a spring loaded, poppet style check valve is supposed to pull the check valve closed when the pump stops, before the water reverses direction and slams the check valve closed.  But that all happens so fast the water still reverses, slams the check valve shut, causing the water hammer.

Adding a Cycle Stop Valve will still allow your pump to produce 10-20 GPM when needed.  The Cycle Stop Valve will just top off the tank at a flow rate of 1 GPM instead of 10-20 GPM.  When the pump is shut off while only pumping 1 GPM, the check valve is only open as much as the thickness of a piece of paper.  From the barely open position, the check valve does not cause water hammer when the pump shuts off.

You can use the CSV with any size tank, but the 5 gallon size shown in the picture is really all that is needed.  But if you have a 50 gallon size tank that holds 15 gallons of water, the CSV should be set at 55 PSI to work with a 40/60 switch.  In this way the tank is filled quickly to 55 PSI, and the CSV fills the last 3 gallons in the tank at 1 GPM rate, making it take only 3 minutes to fill such a large tank after all the faucets are closed.