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On Wed, 26 Apr 2006 23:41:38 GMT, (Doug White)
wrote:
In article , Dave Hinz wrote:
On Wed, 26 Apr 2006 21:38:24 +0100, David Billington wrote:

You can buy fancy spring-loaded space age water hammer arrestors, or you
can make 'em out of 18" of 3/4" pipe and a cap. The latter works great
for my house.

The reason for the fancy commercial ones is two-fold: 1) they will fit in
places where several feet of pipe might be a problem, and 2) the air in
the home brew version will slowly dissolve in the water, and the thing
will stop working. You can always shut off the water & drain the whole
system to get air back in, but why bother?

You have to design your homemade ones to be easily and quickly
drained when the hammer starts up again - 1/2" ball shutoff valve on
the inlet, 1/2" garden-hose faucet for a drain, and a 1/4" or 3/8"
valve on top for air vent is optional but will speed the draining.

Since this is at the laundry a drain is available, though you may
have to remove the washer's drain hose and insert the stub garden hose
while draining the arrestors.

There are two kinds of water hammer. One is the loud bang you get when a
pressure pulse is created by a rapidly opening or closing valve (closing
is more common). The other is an oscillation in water pressure that can
make the pipes moan or in bad cases go bang bang bang as the water
pressure bops up & down. This requires flowing water. Imagine blowing
over an open soda bottle, only under water. The big spikes can be
handled by pre-compressed piston jobs like the Oatey "Quiet Pipes" sold
at Home Despot & some hardware stores. However, eventually the pistons
can stick, and they won't work well for low pressure fluctuations. They
also make water hammer arrestors with a diaphram that are better for
stuff like that, and they can't stick. Those you'll need to get from a
plumbing supply place, probably special order.

Home Despot is stocking the Oatey stored air expansion tanks in the
1 and 2 gallon sizes, meant for handling the temperature expansion
caused by hot water heaters after a pressure regulator. They are
larger than the little inline 'water hammer arrestors', but the stored
air bladder also means they shouldn't lose their charge.

But where's the challenge in a store bought solution? ;-)

-- Bruce --

--
Bruce L. Bergman, Woodland Hills (Los Angeles) CA - Desktop
Electrician for Westend Electric - CA726700
5737 Kanan Rd. #359, Agoura CA 91301 (818) 889-9545
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