Pump hammering after installing accumulator

Jetstreamer wrote:
I had the exact problem and surmised that the bypass type pump does not interface well with an accumulator tank. I spent a lot of time messing with the pressure set screws on the pump and could not get it to work well. I think the accumulator somehow interferes with the way the bypass feature tapers off the flow of water/pressure....
Ended up replacing the pump with one of the older style non bypass types and it works great. I wouldn't be without the accumulator setup..
I'm sure that your hammering issue may stem from the fact that the pump isn't quite cycling correctly and you may have an additional problem with water lines rubbing somewhere...
Just some thoughts from personal experience....

Interesting, I suspected this was the problem, but I didn't find any posts about this online so I wasn't sure. This sounds exactly correct. I'm on city pressure for the meantime, but I'll have to swap back to the old style pump I suppose.

Old-Biscuit wrote:
Shuflo 4008 bypass SHOULD start to open at 40psi

Bypass adjustment is screw in assembly down low and closer to inlet side

Pressure switch adjustment is screw in assembly with wires coming out

Increase set points.......turn set screw 'CLOCKWISE'
Decrease set points.......turn set screw 'Counter-Clockwise'

Bypass should start to open at 40psi....fully open at 65psi
Pump shutoff should be at 55psi


Caution:
Full by-pass pressure setting should be at least 10 psi higher than pump shut off pressure.
If full by-pass is reached before the shut-off setting, the pump will not shut off.

So, if I understand correctly, if I fully turn the bypass adjustment (get it way up over 70PSI or so), it should eventually just never open at all because the pump will shut off before the line sees that much pressure?