- c297-1.jpg - Variable-speed geothermal heat pump in Dulley's home uses a horizontal ground loop. - Photo credit - James Dulley

- c297-2.jpg - This is a high-efficiency oil boiler for floor radiant or baseboard heating. Gas and propane models are also available. - Photo credit - Burnham

- c297-3.jpg - A super-efficient geothermal heat pump shown with and without the front cover. Notice the large air cleaner and water fittings for also heating hot water. - Photo credit - WaterFurnace

- c297-4.jpg - This is a 50-pound bag of shelled corn which can be burned in corn stoves and some pellet stoves. Corn, bought directly from the farm, is on the least expensive sources of heat for a home. - Photo credit - James Dulley

- c297-5.jpg - This is a heat pump used in a hybrid heating/cooling system with a gas, propane or oil furnace. This models uses ozone-friendly R410A refrigerant instead of freon. - Photo credit - Carrier

- c297-6.jpg - This shows the interior of a high-efficiency condensing furnace. Notice the tubular-style heat exchangers near the top.- Photo credit - Maytag