In article , Richard Fangnail wrote:
I have tapping noise from the heat system in my apt building. I know
what causes it. The pipes are expanding from heat.

For many years I heard a fast series of clicks every 30-60 minutes or
so, but lately, I've been hearing a "slow tapping," which is one CLICK
and then five seconds of silence and then another CLICK. This lasts
1-2 minutes.

Same cause.

Do you know why this "slow tapping" would happen as opposed to the old
tapping?

Pipe hangers are older, and now have enough corrosion on them to create enough
friction that the pipe doesn't slide more-or-less smoothly through them like
it used to. Now, it moves in a series of jerks.

Try putting a little bit of grease at every point where a pipe is in contact
with a pipe hanger.

--
Regards,
Doug Miller (alphageek at milmac dot com)

It's time to throw all their damned tea in the harbor again.