I have a kerosene heater in my shop. I bought it about 3 years ago when 5 gallons of kerosene was only $18. It ran about 12 hours on a tank full and 5 gallons lasted quite a while.

Now that 5 gallons of kerosene is about $30 I’m looking for a cheaper alternative heater and was considering the type that runs off propane and secures to the tank top. Are these any good? I don’t know off the top of my head the square foot dimensions of my shop but it’s a little bigger than a one car garage.

How long would a standard BBQ tank run one of these heaters?

A BBQ will last quite some time.  Propane is easier to store too.