I have one for the boiler outside it runs 24-7 for 7 months so I do have one in case it clunks out at 30 below zero thats when stuff usually happens to me any way
I do not......yet. Now that I read this thread, mine will go out the first time it hits -10 during the middle of the night. LOL. I did plan on getting a extra one for the shelf this year anyways. I figure I've gone three years now and it hasn't happened yet and I would guess it's bound to happen at some point.