I have a 1962-built suburban home with original galvanized pipes and
they knock when they heat up and cool. Short of repiping in copper,
are there any solutions: tape, cloth, foam, etc.?

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Request for Question Clarification by haversian-ga on 26 Nov 2002 21:55 PST

Are you sure the knocking occurs as a result of heating or cooling,
and not as a result of a faucet being turned off somewhere in the
house?

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Request for Question Clarification by jackburton-ga on 27 Nov 2002 02:52 PST

Such sounds are usually caused by a phenomenon called 'water hammer.'
With copper pipes you'll tend to hear the noise throughout the house.
Water hammer doesn't accompany flowing water, so if your sound occurs
while water is running, it isn't water hammer. Water hammer happens
when you turn OFF a water flow suddenly (like a dishwasher, a clothes
washer, a toilet or even closing a hand faucet suddenly. Shutting off
the flow suddenly sends a pressure wave down the water line shocking
the pipes and creating the 'hammer' noise.  Most modern homes have
devices called water hammer arresters ( they're called various things
such as air chamber, air cushion, water capacitor, etc.) . They are
air filled chambers connected to the plumbing that let the pressure
wave dissipate harmlessly into a cushion of air. If your banging has
been happening forever then you may not have one. Sometimes these
arresters become waterlogged.
Try this.... Turn off the water to the house at the entry. Find the
lowest faucet in your house--often this is an outdoor garden hose
faucet--open this faucet and then open a few of the indoor faucets at
high locations such as upstairs or at a wet bar and let the low faucet
drain for 5 minutes or until it stops dripping, whichever takes
longer. Close all the faucets and turn the main back on.  Note:  When
you first start using water again there will be air in the lines and
it may spit and sputter with some vigor.
- If this fixes it you have a defective or waterlogged arrester. 
 
Many times a loose washer that is jumping around in the faucet or
valve can cause this noise. This can be fixed by identifying which
valve is the culprit and fixing the washer.
 
Let me know if this corrects the problem

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Clarification of Question by trakkarclay-ga on 27 Nov 2002 08:02 PST

Pipes klunk in the front of the house, closer to the main and the
water heater, when the water is turned on and in the back of the
house, closer to the shower, when the water is turned off. So, what is
causing the klunking with the water on?

My old water heater makes a similar noise, which is caused by
calcification buildup in the heater.  Could that possibly be the
problem?

cheers/bax

No, the klunking is in the pipes.

Is this the answer? Do I need to feed the meter?

Are you using any pressure regulators at all on the water line? I used
to work for a company that made a hose with a pressure regulator
attached to it to reduce water pressure to 40 PSI. See if such a
pressure regulator exists somewhere on the line, and if you can adjust
it, I would try raising the pressure first, but a little at a time
with the water running.

In europe we have plastic pipes, so the "klunking" does not happen.