A great unit for heating my shop, which is approximately 20‘ x 18‘. I took the unit and Ran exhaust through an old water heater tank that I modified and filled the inside with sand. Using the exhaust heat, I ran that through where the water would’ve went. It actually is a heat sink, allowing the heater to put out the regular heat through the discharge and using the exhaust to heat the sand up which intern last for hours heating up my shop.