help me figure out this noise

I live in an apartment. The apartment has natural gas appliances. The natural gas furnace lives in a little locked closet above the stairway going up to the second floor. I am pretty sure the natural gas water heater is in there too (I hear a loud click every once and awhile that I assume is the water heater).
Now for the strange part. When I am in my bedroom at night I sometimes hear a strange noise. This noise happens randomly (although last night it seemed more frequent) in 5-10 second intervals. It sounds like pressure is being released (it sounds like when you let air out of a ballon with that whiny sort of noise).
Now I am thinking about calling the maintenance people but the noise is so random and I am not sure what it is that I am afraid that they might think I am crazy or something.
In the last two weeks the noise has only been happening while I have been going to sleep (about 12:00) but I never noticed it during the mornings. Last night the noise seemed to be occuring throughout the night. I woke up a few times last night and heard this funny whiny noise. I also noticed the noise last summer but it seemed to go away during the winter and then it started coming back as we came into spring. I think the noise is coming from the attic (not sure what would be in the attic making this kind of noise) but since the noise randomly occurs and only happens for 5-10 seconds, I never have enough time to figure out where its coming from.
Any thoughts of things I should look for? I might call the maintenance folks but it would be good if I had better info for them.
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Michael Dauria wrote:

<SNIP>
My prime suspect would be the water heater.
The fact that it happens (only?) late at night could mean that city water pressure jumps up then.
Find out from maintenance where the heater discharges to when the relief valve opens. Might be to an indoor drain or even to the outside. Monitor that for signs of water being discharged. If it *is*, you have some leverage to work with.
Jim
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Water heaters sometimes make this sort of noise. It usually means some sort of deposit/hot spot on the inside of the casing is causing localized fairly intense water bubbling. Especially calcium deposits on the bottom impeding heat flow.
Your first course of action is to get the HWT flushed.
It's easy to do yourself, but talk to the super first.
One other thing to check - is there any water dripping from the HWT?
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Chris Lewis, Una confibula non set est
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Mice having sex?
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Christopher A. Young
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