Those little rods do nothing for the humidity. They only create a small air current (Hotter air rises) and keep the area warmer than the surrounding enviroment to ward off condensing moisture on the contents. I think some type of dessicant would be useful to absorb some of the moisture. Buy a temp/humidity gage from Radio Shack and mount it in the enclosure and monitor the humidity. I think most of the safe manufactures say keep the humidity around 40 or less.

 
Thanks everyone for your help. I am installing vents in the door to promote air circulation, but there is no duct work close to this closet,so I was wondering if it is a good idea to put a small battery powered fan in the door vent to promote air circulation? If so, does anyone know of a source for such a fan? Thanks! Joe S

 

I would take a look at either running a small dehumidifier in the closet or going with a vapor phase inhibitor system in it.  The downside to the dehumidifier is that you'll have to empty the tank every day to two unless you can plumb a line to a floor drain.  The emitters prevent oxidation, but you'll need a couple of big ones for a 7"x2" area.  Check out (You need to Login or Register to view media files and links) for this type of stuff.

David
Montezuma, IA

In a closet, I would opt for a Golden Rod or two.  They can't break like a light bulb, and they seldom ever burn out.  I would still suggest a vapor unit like the Bullfrog along with either a Golden Rod or conventional dehumidifier...our local Commissar of Electricity occasionally fails to feed the hamsters during storms, and the humidity raises very quickly when the ac and dehumidifier go out!

David
Montezuma, IA

Hello Joe. Good question and good replies.   
I spent several years in the Panama Canal Zone and did a lot of shooting while there. We kept our firearms in a vault that was wired and we used heating element bulbs that the Govt. provided. They did a great job. We also kept most of our clothing in a similar "dry closet".
For extra protection I used R.I.G. Rust Inhibiting Grease on all my firearms. I was sent to Venezuela for a period of time and was not able to check on my firearms as I usually did. Upon return I had expected some problems. Nada, not one problem with rust.
I still use RIG and have not found anything better for my use. I know there are many other product out there but RIG works for me.
I have a similar vault in my home that you describe in yours. Some firearms are stored in a safe that is in thenroom and some just in the room. It is on a outside wall also.  I have had no problems with rust of any kind.
The light bulb idea (25w) sounds good but if the bulb burns out and you don't check for a while ----.!
  I strongly recommend RIG.
  What ever you do, enjoy them and keep shooting.  4227 

I would be concerned about the light bulb heating anything in close proximity.  Remember those little toy ovens for little girls to play house with?  They could bake a cup cake with a 60 watt bulb.  Something to think about.
Keep on hav'n fun!

yes - added sheetrock (drywall) will add to the fire protection - that is how the gun safe manufactures give their safes added fire protection.
u have a good day now - the rimfire