Chimneys and Heating Systems
(reprinted with permission from Grinnell Mutual Reinsurance Company, I-80 & Hwy 146, Grinnell, Iowa 50112)

A. Chimneys and Vents

  1. Gas fired appliances equipped with draft hoods and other equipment listed for use with Type B gas vents may be connected to Type B vents, that have a one inch clearance from combustible material.  Appliances and heating systems burning wood, coal, or oil should use an approved masonry, UL or ULC listed prefabricated all fuel chimney.  chimneys should have at least a two inch clearance from combustible material.

  2. Chimneys or gas vents should terminate three feet above the point where they pass through the roof and at least two feet higher than any portion of a building with ten feet of the chimney or vent.

  3. Provide openings into attic spaces to permit yearly chimney inspections.

  4. Chimneys and gas vents should be checked and maintained on a periodic basis.

B. Smoke Pipes-Chimney Connectors

  1. A double wall ventilated metal thimble three times the diameter of the chimney connector should be used if the chimney connector passes through an interior wall.

  2. Smoke pipe should have an air tight connection into the flue opening using either a thimble or cemented in place using refractory cement.

  3. Provide at least 18 inches of clearance from smoke pipe to combustible material.  Clearances can be reduced when the combustible material is protected in accordance with National Fire Protection Association's pamphlet #211 - Chimneys, Fireplaces, Vents, and Solid Fuel Burning Appliances.

  4. Chimney connectors shall be as short as practical, (not longer than 10 feet), make no more than two 90 degrees bends, and slope 1/4 inch per foot from stove toward chimney.

  5. Joints in a woodburning stove pipe should fit tightly, be secured with sheet metal screws, and should be assembled to funnel any liquid creosote accumulating in the pipe back to the stove where it will burn.

C.  Heating Systems

  1. All heating systems should be tested and listed by a recognized testing agency such as Underwriters Laboratories or the American Gas Association.

  2. Clearances to combustible material for agricultural heaters (suspended unit, portable, electric, etc.) and residential heaters (such as furnaces, boilers, portable heaters, etc.) need adequate clearance from floors, walls, ceilings, and other combustible material in accordance with the clearances specified on their nameplate or appropriate National Fire Protection Association code book.

  3. Clearances for woodburning stoves to combustible walls shall be 36 inches unless specified differently on their nameplate.  Adequate floor protection is also needed depending upon the type of unit and height of the legs.

  4. Establish a routine maintenance program before each heating season.  Furnaces, boilers, oil burners, wood burners and their operating and safety controls, vents and chimneys should be checked by a qualified serviceman.

  5. The fuel supply lines plus all connections and joints should be tight, securely supported, and protected from physical damage.