I serviced HVAC for a number of years
ANY salamander type device fired with ANY fuel generates large amounts of moisture.
ANY direct fired device of this nature is an explosion hazard. I simply cannot believe how many people seem to get away with this. It's only a matter of time.......
Even an electric furnace CAN be an explosion hazard, because of arcing in the controls, as well as the possibility that the elements may get hot enough to reach an ignition temperature.
(Think of some portable heaters you've seen--red hot elements)
I believe the ONLY safe heating device for a paint booth is:
Electric that has appropriate shielded elements, think in terms of your baseboard heater. HOWEVER the controls must be spark proof as well
Gas/Propane/ Oil that is in the form of a furnace type device with a HEAT EXCHANGER so that there is isolation from the combustion and paint booth.
Additionally, something like a furnace MUST be OUTSIDE the booth. An atmospheric burner, taking in polluted air into the burner, presents not only an explosion/ fire hazard, but.....
any chemicals in the air ALSO hasten the destruction of the heater.
I've worked on equipment in places like laundries (bleach and soap) beauty parlors--various chemicals, photo/ print type shops--all KINDS of chemicals, and ANY of these types of chemically laden environments are VERY hard on the equipment, because when you HEAT or BURN a chemical, it usually makes the reaction much more severe
The thing is, the explosion hazard does NOT only come from vapors like paint thinners, etc in the air. The hazard ALSO comes from the DUST hazard. Various kinds of dust are very explosive. (Google stuff like wheat explosions)
http://www.osh.dol.govt.nz/order/catalogue/archive/dustexplosions.pdfI'm no expert on the electrical code, but paint booths are required to be wired in terms of exposion proof devices and fixtures
