Our smaller furnaces are constructed from stainless steel, whereas our larger commercial furnaces are constructed from carbon steel. All of our models are EPA Accredited Laboratory Tested. Also, note that all units are UL approved. The water tank on the furnace is vented to the atmosphere to eliminate the safety hazards common with a pressurized boiler. The primary OHI design goal is to give years of good service and make it easy to maintain.
All furnaces are weather resistant and require no building or protection from the weather.