This home-built hot water furnace has served Roger Foster well for several years. Overall length is 5 ft. long. The firebox will take up to a 3-ft. log and it's 2 ft. wide. There's a water jacket on the top and sides of the fire box which holds 2 1/2 in. of water. Water is heated by the fire and then travels to a 200-gal. reservoir where it circulates through 120 ft. of 1-in. copper pipe. Heated water in the pipe transfers its heat to the water in the reservoir. Then the heated water in the reservoir circulates to the rooms and radiators.

An "aquastat" controls the flow of hot water. It turns on the circulating pump when water temperature reaches 180 degrees.

The furnace has both natural draft and a fan-forced draft. The forced draft is only used to get the fire started.