Author Topic: Water Hammer when Pump turns ON  (Read 3489 times)

dontribi

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Water Hammer when Pump turns ON
« on: August 31, 2015, 11:53:30 PM »
We are on public water and lack the necessary pressure to supply the house.  I've installed a CSV valve and J15S goulds pump to increase the pressure within the house.  I have an issue with a water hammer when the pump kicks on (very loud bang and then slurping sound).  So when the pump kicks off you get the bang and then it sounds like sucking into the pump until it reaches full speed and then it runs normally.  I've had a plumber come out to check to see if the pump had air in it and it was given the all clear.  I purchased the pside-kick and installed it with all factory settings.

The setup is as follows:

Inbound pressure from the street supply is about 38-40psi (not enough to get through everything in the house).  1" supply line going into a water softener from the street, 1" out of the water softener into the inlet of the J15s pump with CSV and then fed into the house 1" pex line once it is past the CSV valve.  The water hammer does not happen at shut off only at pump turn on.  The csv is set to the 40/60 setting and pressure is maintained perfectly.

I was thinking of getting a water hammer arrester and putting it on the out of the water softener as close to the out connection as possible but I've been reading mixed results on how they function.  I'm not sure what else to try to stop the water hammer at pump start to keep it quiet.  Any guidance would be appreciated.

Cary Austin

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Re: Water Hammer when Pump turns ON
« Reply #1 on: September 01, 2015, 07:03:04 AM »
Water hammer at pump start is nearly always caused by having too many check valves or having a single check valve in the wrong location.  It would be best to have a single check valve on the suction line coming from the supply.  An additional check valve anywhere else in the system will cause water hammer on pump start.  The little tank that comes with the Pside-Kick kit is all you need for surge suppression, you just have to make sure the check valve is in the correct position.