banging with hot water

[RodgerW]

I have an Aquasource Pull-Down Kitchen Faucet. The manual lists:
Item 0328012
Item 0328011
Model 65710N-B8303D2
Model 65710N-B8327H2

I'm not sure which applies, though the difference appears to be if it comes with a Escutcheon or not is all.

• No other plumbing does this.
• If the hot water is on partially, it doesn't occur.
• It occurs every time.
• If I hold down the spray button on the faucet it usually doesn't occur but sometimes it does. This model sprays from the same area as it pours and doesn't have an independent spray hose/fixture.
• If I turn the hot water supply off under the sink and then turn the hot water faucet on, it doesn't make any noise (obviously)... but with the slightest amount turned back on at the supply, the banging starts again.

I think that answers the questions that I usually see in forum threads.
Any help would definitely be appreciated!

[rmw]

It sounds like you have a water hammer caused when the water is turned on or off suddenly that is causing the pipe to bang.

you should install a water hammer arrestor right before the supply valve under the sink and if possible secure the pipe better.

[Nestor]

Sounds like a loose washer

I would check with Aquasource to see if that faucet uses rubber washers or not. If so, then the problem is that the rubber washer on the hot side is loose.

You see, if the washer can move forward and backward on the brass screw holding it in place, you have an interesting situation that can make your faucet sound like a machine gun:

Because the AREA of the washer is larger than the area of the seat the washer covers, and force is equal to pressure times area, then as soon as you start to open the faucet, water starts to flow under it. But, if the washer is loose, water can ALSO flow under the head of the brass screw and through the hole in the washer and pressurize then microscopically small space behind that washer. Now, since force is equal to pressure times area, there is a NET force that will push the washer forward against the equal water pressure at the seat. As that washer moves forward, the microscopically thin space behind it fills with water, and your washer effectively turns into a water pressure driven piston that closes tightly over the seat again.

But, no sooner does the washer seal off the flow through the seat that water pressure can't get in behind that washer any more. In fact, now the pressure at the brass screw is only the hydrostatic pressure of the water in the faucet's spout. So, the still pressurized water behind the washer leaks past the brass screw in the opposite direction this time to release the pressure holding the washer tightly against the seat. Since it was that water pressure behind the washer that caused the washer to move forward in the first place, the supply pressure acting over the smaller area of the seat now overcomes the negligible pressure behind the washer, and pushes the washer open again, allowing water to flow to the spout.

It's that rapid forward and backward motion of the washer that causes water to start flowing and almost immediately stop and then almost immediately start again, and stop again which makes your faucet sound like a machine gun.

I'd just replace the washer and while you're at it, replace the brass screw holding that washer in place with a stainless steel one. Often, a brass screw will "de-zincify", meaning that the zinc leaches out of the brass, leaving a reddish brown material for the head of the screw which crumbles under the force of a screw driver trying to turn the drive in that head. Stainless steel screws won't do that.