Profile: Tjernlund Products, Inc. designs and manufactures oil fired forced air furnaces. We offer gas fired furnaces and custom packaged roof top heating & cooling equipment. Our engineering and manufacturing departments feature the latest technology in 3D CAD design and CNC turret presses and brakes. Our products include side wall vent system, in-line draft inducers, in-forcer fresh air intake systems, ventilation fans, santek electronic air cleaners and cooling fans.