My flue (sp) is stuck open. I have a whole house fan for the summer, so I can't have it opened. It was fine last year. I have tried silicone spray... working it, working it... Nothing!

Any suggestions:confused:

Careful with any spray. Silicone spray is flamible unless you buy the non flamible type of wd 40. If it ever gets cool enough you could run a fire through it and see if that loosens it. Be very careful. Or have a professional chimney sweep come out for a good cleaning and inspection. Sometimes over time water can get inside or humidity and caus them to rust tight. If you do run a fire through it it should expand the metal and free it up if that is the root caus.

I am a chimney sweep.
Use two wrenches; adjustable, socket, open or closed end, and with one on each end of the bolt, loosen the bolt holding the handle to the damper support brace.

Then tighten to where it is stiff but not too tight.
I have used a lock-washer to make the handle resistant to wind pulling the damper open.

If you can't do that, fill a garbage bag full of newspaper sheets compressed into balls and plug the opening.

If you forget and start a fire, it will open on its own!
But better to not forget and first remove the plug.