Any direct vent propane unit heaters?

[arrowhead]

I'm ready to pull the trigger on a Maxx hanging heater, but thought I'd ask first if anyone know of a similar unit but direct vented. I use my shop for welding/grinding/bodywork/painting and am concerned about buildup of dust on the burner and heat exchanger. I'm not so concerned about an open flame because I never leave any heater running while painting anyway (just blows dust and dirt around), but in a working shop the buildup of dust can be considerable and could clog the ports on the burner. Plus, when the shop exhaust is on, it creates a negative pressure that would **** the flue gasses back in. All these issues can and will be dealt with, but I think a direct vent would be a better choice.

 

[Highbeam]

You're looking for a sealed combustion style. Very common. Usually an upgrade to the base model. I see no drawbacks to burning outside air for combustion.

 

[JB40]

For dusty areas, you may want to consider a tube heater. No fan to kick up dust. More efficient also. There's a collar on the burner box as standard if you want to hook-up flex duct for fresh air intake. Here's an example: http://www.h-mac.com/detroit-radiant-ld-20-40.html