The baseboard electric heater in our home clicks when it's (a) on, and
(b) the room is cold. It's driving us nuts at night! Is there
something simple we can do to stop it from clicking? Some nut we
tighten, or thingy we can oil?

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Clarification of Question by jhabley-ga on 31 Dec 2002 12:16 PST

MarshallW - Thanks... it's an electric baseboard, though, not an older
hot-water type radiator.

bobthedispatcher - Seems to be the metal itself clicking, not a relay
of some sort. We'd thought it was simply expansion as well, but it's
the only heater in the house to do that.  One would think they'd all
do it...?...

Without further examination it is hard to be sure, but a good
possibility would be that the expansion (caused be heating) of metal
parts was causing it. Possibly a section that is
rivited/screwed/bolted has become just a tiny bit loose, or a corroded
joint is allowing some twisting as it heats up. This would probaby be
worst when very cold, and lesser as it warms up. Typicaly the noise
stops shortly after the power is turned off (or it reaches the desired
temperature).

Other possibilities are the thermostat (if any) and any other switch
or relay
that might be cycling, or not staying on.

Having lived with a boiler-and-radiator heating system (operating on
the same principle as a baseboard heating), I wonder if you might have
air in your baseboard's water line. Over time, as water courses
through the heating system, air leaches out from the water and
collects in the uppermost parts of the line it can reach; a natural
phenomenon, but it can lead to noises within the line (not to mention
reducing the radiator's efficiency). One end of each radiator had a
"bleeder valve" which I would open every six months or so in order to
release built-up air. The valves had a squarish knob onto which one
would place a turning key; with that key gone missing, I always used
needle-nosed pliers to turn the knob open and closed. It also helps to
have a bucket or dish to catch any rusty water that might spurt out
with the released air. Perhaps your baseboards also have such valves.

In regular plumbing lines, built-up air can create a related
phenomenon known as "water hammer", a banging that occurs as one shuts
off the tap.

I would be interested to hear whether this suggestion applies to your
situation.