Wood Heat

Precautions for Using Wood Heat

Buying a Wood Stove

If you are planning to install a woodstove, or if you have already installed one, your reasons for considering wood as a heat source will vary from wanting to save on heating costs to having the cheery warmth of a woodstove in a room where family and friends gather. Wood heat can provide many hours of enjoyment during the winter months; however, woodstoves require extra care in installation, operation and maintenance as compared to gas, oil, or electric heating units. That is why we have prepared this article of suggested safety precautions. Please read it carefully.

Select a Quality Stove

Before you buy a stove, visit the showroom of several reputable woodstove dealers. Examine the stoves for quality workmanship. All stoves are not created equal. Do not consider buying a stove unless it has been tested and approved by the Underwriters Laboratories (UL), Building Officials and Code Administrators (BOCA), or some similar testing organizations. Most stoves will have a tag attached indicating whether the stove design has been tested under extreme conditions of heat.

Install the Stove Properly

Improper woodstove installation has caused the loss of many homes and lives. Do not “cut corners” to save a dollar on installation. Whoever installs your woodstove should follow the installation guidelines of the stove manufacturer or the guidelines recommended by the National Fire Protection Association.

Clearances – A Must for Safety

Sufficient clearances around your woodstove and flue pipe are vital because of the large amounts of heat produced. We suggest a clearance of at least 18″ from noncombustible surfaces and 36″ from a combustible surface regardless of the type of stove you buy. Commercially made heat shields provide safe protection for walls and floors. You can also use rock or brick for wall and floor protection. Do not use imitation brick or rock for wall or floor protection. Floor protection must extend under the stove and outward for a distance of at least 18″ in front and on each side of the stove. This will provide protection from heat, sparks, and coals which may fall out.

Flue Safety

Your stove will have a stove pipe and flue pipe to exhaust the smoke. The stove pipe is a single wall pipe, blue or black in color. It comes out of the stove and leads into the flue pipe. Stove pipe should be:

  • 24 gauge or thicker
  • Installed with the crimped end down
  • Fastened together with at least 3 machine screws at each joint
  • As short as possible, running vertically
  • At least 36″ from any unprotected combustible material.

Stove pipe is used within the interior of the home but must not pass through the ceiling into the attic or through the roof line to the outside. Flue pipe must be used once the stove pipe leaves the interior of the home. Use a metal or fireclay thimble when passing the stove pipe through a combustible wall. If you must vent through a combustible wall, convert from stove pipe to class A metal flue pipe.

Remember, the most trouble-free system will have few, if any, horizontal pipe sections and elbows. Vertical piping gives the best draft and allows creosote and soot to fall back into the stove to be burned. Most woodstoves will have a prefabricated metal chimney, or flue pipe, made of “triple wall” construction. Insist on a class “A”, all fuel, flue pipe with a “UL 103HT” stamp of approval. These flues have been subjected to test temperatures of 2100 degrees and can withstand most chimney fires without major damage. As the flue exits the roof line, it should be:

  • 2′ above any portion of the roof within 10′ of the flue
  • 3′ above the roof junction.

Be sure to top your flue pipe off with a chimney cap. A cap will keep out birds and rain and will retard any sparks which are emitted.

Use the Right Wood

Burn hardwoods like oak and hickory. Be sure the wood used has been seasoned at least six months. Seasoned wood will have bark that is cracked or shrinking and there will be cracks radiating outward from the heartwood, like wheel spokes. If the wood is wet or freshly cut, the moisture content will be high which will cause a smoldering fire and will reduce the heat value of the fire. Slow burning or smoldering fires will increase the amount of creosote build-up in your stove and piping system.

Creosote: What is it?

A certain amount of creosote will be found in all wood burning appliances. It is created by unburned gases released from the wood. Creosote will accumulate inside the stove and its piping system. Its form can be flaky and crystal-like, or it can be glossy and tar-like, which is the most dangerous stage of creosote build-up. Creosote is the cause of most chimney fires. Creosote can not be completely avoided; however, maintaining a small hot fire with an open draft and the use of seasoned wood will help eliminate the chance of having a tar-like creosote build-up.

Clean the Flue

This is one of the most important duties of a woodstove owner. Frequency of use, the type of fires you build, the length of your piping system and the type of wood burned will dictate how often the flue needs cleaning. We recommend cleaning a flue at least once a year. Call a professional chimney sweep to clean your flue. They will have the tools and expertise to properly complete the job.

What About Inserts?

Inserts set inside the fire chamber of a standard fireplace and function like a woodstove. They are very efficient and can have fans installed to disperse the heat. The insert uses the existing fireplace flue; however, be sure there is a flue pipe extending up from the insert making a direct connection into the existing chimney flue. Many inserts have been installed without a direct connecting flue pipe which allows creosote and soot to fall on top and behind the insert. This could create a fire hazard and makes cleaning more difficult. An insert must not be placed inside of a prefabricated metal, “Zero-clearance” fireplace unless the insert has been designed especially for the fire place, by the same manufacturer. Follow the same rules outlined for woodstove installation, use, and maintenance for safe operation.

Wood heat can be dangerous. If you have a woodstove and would like extra insurance coverage for your home, please contact a Farm Bureau Insurance agent.