Siebring Manufacturing, Inc. offers Heat Reclaimers using industrial components including a very heavy duty fan. The Heat Reclaimer fits over the chimney of any furnace when the chimney is on the top of the furnace.  There is an 8” model and a 9” model.  The Heat Reclaimer has reduced the chimney temperature by 150 degrees F on every model tested, which is about 5% of fuel efficiency. If a unit normally uses 1000 Gallons of fuel, you will save 50 gallons.  The Heat Reclaimer is used in conjunction with a barometric damper (supplied as standard equipment by Siebring) and a good chimney cap that prevents downdrafts or excess suction of heat up the chimney.  Well installed chimney equipment can make a difference of 20% – 30% in fuel savings.