My manual says not to completely close the air off with the blower running and I don't. It turns out that I didn't properly explain that to the wife who enthusiastically keeps the insert running when I'm not there. When I got home last night it was humming along with secondaries and everything was nice and warm. I noticed the air was fully closed. She's been running it that way every time.
Is this a danger to the unit? If not, why would the manual advise against it?
Is this a danger to the unit? If not, why would the manual advise against it?