Quick answer: Torpedo heaters are cheap to buy but loud and smelly, and they blast heat to the ceiling. Propane radiant is quiet but ties you to cylinder swaps and open elements. Infrared diesel — like Rex Nordic — runs at 48 dB with no flue and no smell on cheap pump diesel, and its low fuel use keeps running costs down, which is why all-season shops end up here.
| Rex Nordic infrared diesel | Torpedo / forced-air | Propane radiant | |
|---|---|---|---|
| Noise | 48 dB — talk over it | Loud; conversation is hard | Quiet |
| Smell & fumes | Odor-free triple combustion, no flue | Noticeable fuel smell into the space | Low odor; adds moisture |
| Heat type | Radiant — warms people & surfaces | Convection blast — rises to ceiling | Radiant |
| Electricity | ~80 W | Fan motor required | Usually none |
| Fuel & refills | #2/renewable diesel, 6.6–18.5 gal tank | Kerosene/diesel, small tanks, frequent fills | Cylinder swaps |
| Thermostat / unattended | Precise built-in; holds overnight per manual guidance | Basic or none | Varies |
| Open flame exposure | Enclosed burner behind grille | Open combustion | Exposed elements common |
| Operating cost | Lowest — low fuel use keeps running costs down | High — fuel plus frequent refills | Cylinder swaps add up |
The math that decides it
If you heat regularly, fuel is the lifetime cost — and pump diesel is the cheapest professional heat per BTU in most regions. Add the productivity tax of a torpedo's roar in an occupied shop, and the fuel savings add up for daily users.
Safety note
Any fuel-burning heater used indoors must follow the manufacturer's ventilation and clearance guidance and local codes. See each Rex Nordic manual for placement requirements.