I have the same type of thermometer in my garage - but for a different reason - I'm at the far other end of this spectrum. My garage has no ceiling and with the full length ridge vent, any heat that my trash can heater puts out goes straight up into the rafters and quickly out that vent. I use the thermometer to keep track of the air temps in the rafters and I turn on a fan to blow the warm air down to keep me from freezing - lol.
Long story on the garage ceiling. No joists - just rafters and rafter ties. They are roughly 4' apart so no way to do a ceiling. However I am planning on hanging some 8 mil plastic in an effort to keep more warm air below the attic - at least for a little while before it cools off since again - no insulation - lol. I should only have to rough it for the remainder of this winter because my pole barn is built, sided and roofed but not much more yet, and should be more than ready for whatever next winter brings us.
But your system is very impressive - especially at only R19! I don't think most homes are even that efficient. You must have done an awesome job of sealing that place up! I can only hope to get that kind of result in my pole barn. But dang - thanks for giving the rest of us something to shoot for!!
