I heat with a simple 30,000 BTU flame thrower bazooka type heater.

Be careful with these types of heaters. They are not meant to perform
in an enclosed area. If the oxygen is depleated enough through the
combustion process, the products of combustion could result in
'incomplete' combustion producting carbon monoxide.

I have no first hand experience, but I thought I heard once that propane
powered heaters also introduced moisture into the air? Probably not a
desirable feature in a woodshop.

Anthony