Yeah I read that.
“The use of multiple check valve is to helps to absorb the shock of large volumes of water dropping in the pipe when the pump cycles off.”
As usual many people use multiple check valves as a Band Aid for problems that should not be happening. The spring in a spring loaded check valve should close the check valve before the water reverses direction. So there should be no water “dropping” to start with. Then if the water never drops, it never creates the “shock” that would need to be “absorbed” by any extra check valves. Then of course if the pump is not “cycling”, the check valve is not even being used, as the check only works when the pump shuts off.
“It is very important to properly install “A” check valve to help insure a trouble free water system.”
“Without “A” check valve or improperly placed, several undesirable conditions may immediately occur….conditions such as motor and pump backspin when during shut off; pump up-thrust during startup; and water hammer, which can occur at either pump start up or shut down.”
Looks like Franklin only cares that “A” check valve be used to prevent these undesirable conditions. “Check valve manufacturers often recommend multiple check valves.” Of course they do, they make check valves. They would like for you to put one at every joint no matter how bad it is for the system.
I also read…”There is however, a risk of water hammer if the lower check valve fails”. And….”Vacuum causes water hammer when the pump starts”.
There is no “risk of water hammer or a vacuum” unless you use more than one check valve.
Unless the upper check valve leaks back, there is always a vacuum between multiple check valves. This is obvious in the video you made, which shows a tremendous water hammer when the pump starts. Not only does the pressure gauge peg out instantaneously, but you can also hear and feel the shock when the pump starts and the water hammer occurs. You can also see the gauge go erratic when the pump shuts off and those check valves start bouncing.
Your video proves my point. Multiple check valves cause water hammer.
“The use of multiple check valve is to helps to absorb the shock of large volumes of water dropping in the pipe when the pump cycles off.”
As usual many people use multiple check valves as a Band Aid for problems that should not be happening. The spring in a spring loaded check valve should close the check valve before the water reverses direction. So there should be no water “dropping” to start with. Then if the water never drops, it never creates the “shock” that would need to be “absorbed” by any extra check valves. Then of course if the pump is not “cycling”, the check valve is not even being used, as the check only works when the pump shuts off.
“It is very important to properly install “A” check valve to help insure a trouble free water system.”
“Without “A” check valve or improperly placed, several undesirable conditions may immediately occur….conditions such as motor and pump backspin when during shut off; pump up-thrust during startup; and water hammer, which can occur at either pump start up or shut down.”
Looks like Franklin only cares that “A” check valve be used to prevent these undesirable conditions. “Check valve manufacturers often recommend multiple check valves.” Of course they do, they make check valves. They would like for you to put one at every joint no matter how bad it is for the system.
I also read…”There is however, a risk of water hammer if the lower check valve fails”. And….”Vacuum causes water hammer when the pump starts”.
There is no “risk of water hammer or a vacuum” unless you use more than one check valve.
Unless the upper check valve leaks back, there is always a vacuum between multiple check valves. This is obvious in the video you made, which shows a tremendous water hammer when the pump starts. Not only does the pressure gauge peg out instantaneously, but you can also hear and feel the shock when the pump starts and the water hammer occurs. You can also see the gauge go erratic when the pump shuts off and those check valves start bouncing.
Your video proves my point. Multiple check valves cause water hammer.