Thank you. I tried Google, but evidently I heard a corrupt version in my childhood, so I missed "damper".

Come to think, we were a Freudian family.

Of course, even with "damper" instead of "lever", one might be reminded of

Ringtail Tom is the stuff.
He's the boss around the town,
And if you've got your heat turned up,
You better turn your damper down.