This is Part Two of a two-part series based on the Chimney Fire Prevention class held by Instructor Fred Chamberlain at the Wakefield Fire Hall on Wednesday, September 10, 2008. Part One is available in the Chronicle archives.

WAKEFIELD, MI - Monday, September 15, 2008 - On Wednesday, September 10, 2008, the Gogebic County Firefighters' Training Council sponsored a free Chimney Fire Prevention class. Instructor Fred Chamberlain attracted a large crowd area residents and firefighters to the class held at the Wakefield Fire Hall on the city's main street. The class was extremely interesting and very informative. Representing the media at Wednesday's seminar were Lou Bonagura from IronwoodInfo.com and yours truly.

WAKEFIELD, MI - Tuesday, September 16, 2008 - Back in 1985 Auburn University was awarded a grant to determine whether or not long-leaf yellow pine could be used satisfactorily as a home heating fuel. It seems many trees of that species were diseased and needed to be destroyed. As a result, there was a large supply of wood that appeared to have no purpose.

According to Instructor Fred Chamberlain, long-leaf yellow pine is incredibly pitchy. In fact, sawdust from the species can easily be packed into a ball.

Auburn University decided to make a comparison between a number of different woods. In three separate wood stoves, three different woods were burned. In one stove they burned hickory. They burned oak in another, and long-leaf yellow pine in yet another.

Water coils were placed around the chimneys of each wood stove. The purpose of the coils was to control the chimney temperature. They wanted to keep it low in order to deliberately create creosote. (Remember that creosote will not collect in a stack that reaches 300 degrees.)

Notice in the diagram above that the hickory produced the most creosote; oak produced the second most; and long-leaf yellow pine produced the least. On the surface, these findings defy logic. It's been a common belief that burning soft wood was an invitation for a chimney fire. Why did the hardwoods produce more creosote than the pitchy pine?

The answer lies in two pieces of information that were presented in yesterday's article. Hardwood produces more BTU's of heat per cord than softwood, and all but two components of creosote were flammable. Under normal conditions, without temperature restrictions on the chimney, the hardwood will burn hotter than the softwood. More creosote will be consumed in the firebox as a result, and less will accumulate in the stack. Remember that the key to efficiency and safety is a hot fire and a hot chimney. Maintaining a stack temperature of 300 degrees will prevent the build-up of creosote in a chimney.

When one compares hardwood to softwood, hardwood is more dense. So 50 pounds of hardwood has less volume than 50 pounds of softwood. A fifty pound bundle of hardwood is smaller than a 50 pound bundle of softwood. When compared pound for pound, they produce equal BTU's of heat.

According to Chamberlain, the Auburn study did much more than prove that long-leaf yellow pine could be used for fuel. It proved that all wood could be used. The key to a clean, safe burn is to maintain the stack temperature, and to improve the efficiency of the burn. Opening the damper and reducing the charge (size of fire) provides a cleaner, hotter fire and reduces the likelihood of a chimney fire.

Now, back to the two wive's tales mentioned in yesterday's article. Remember that Mr. Chamberlain claimed that burning potato peelings in a wood stove prevented chimney fires. He said it works! Why? Not due to any magic or any special chemical in the peeling, but simply because it takes a hot fire to burn wet potato peelings. A hot, efficient fire, means a hot stack. And a chimney temperature of 300 degrees or more will not develop deposits of creosote. A hot fire is also the reason burning an aluminum can prevents chimney fires.

What causes creosote build-up? According to Chamberlain, when a wood stove exhaust chimney is not hot enough to prevent distillation of flue gases, creosote will collect on the walls of the chimney. Therefore, it is very important to build smaller, hotter fires and to allow the chimney to heat up to 300 degrees or more.

Some recent developments in the "modern" wood stove were discussed Wednesday. A catalytic combustor, according to Chamberlain, is  a good thing. It's special construction forces things that would not normally burn to burn. It creates a hot fire. A Heatilator, on the other hand, is a bad thing. It burns wood at a lower temperature. A lower temperature means less efficiency. Less efficiency means cooler stack temperature, and an invitation for a chimney fire.

A member of the audience at Wednesday's meeting pointed out that she had a earth stove with a catalytic combustor, and the manual says not to burn softwoods. Chamberlain explained that cooler burns will coat the converter with creosote and make it less efficient.  He said that a hot fire was essential for a converter to work. He said softwoods could be used provided there was a small enough charge to force a hot, efficient fire.

Chamberlain pointed out that "air tight stoves" provide a "secondary burn." Many of the chimney gases are recycled back into the fire. This gives many of the combustibles in creosote and chimney gases a second chance to burn.

Which is better, a masonry chimney or a metal chimney? Chamberlain told the class that Underwriters Laboratories (UL) did several studies to determine the safety of metal chimneys. Today all metal chimneys sold in Michigan are required to have a UL stamp of approval embossed directly on the flue. Modern metal chimney systems have two layers; an inner layer and an outer layer. The two layers are separated by a fire-retardant insulation.

Chamberlain explained that it is very unsafe to use any chimney after a chimney fire has occurred in it. The extreme temperatures that develop in the chimney during a fire cause the insulation between the layers to breakdown and settle. When a new fire is introduced to the damaged chimney, hot spots are created and the outer layer can become dangerously hot. Temperatures of roughly 350 degrees can cause a structure fire. If the weakened hot spot on the chimney contacts any part of the house framing, risk of fire is extremely increased.

Chamberlain told the class that many firefighters prefer masonry chimneys, but he pointed out that metal ones can be just as safe, if not safer, if properly used. Chamberlain pointed out that all current masonry chimneys are required to have linings in them. The linings are either made of metal or of tile. The mass of a masonry chimney can be a contributing factor in causing a chimney fire. He said massive masonry chimneys are much harder to bring up to the optimum temperature (300) that doesn't allow flue gases to settle on the chimney walls.

He told the crowd that a "shock loaded" masonry chimney instantly becomes damaged. It is not unusual for new masonry chimneys to be cracked shortly after installation. Because of this, a masonry chimney cannot hold up to the UL standard of a metal one. The "saving grace" of a masonry system is the very thing that causes the chimney fire to begin with. The mass of a masonry chimney helps to contain the fire.

Chamberlain stressed the importance of getting the word out to the general public about wood burning appliances and chimney fires. To accomplish this goal he supplied the following list:

• Wood - The amount of heat generated by seasoned wood, green wood, softwood, hardwood, etc. varies. It's important to create a hot fire and to warm the chimney up to 300 degrees or more to prevent accumulation of creosote and to prevent chimney fires. Seasoned wood does not remove BTU's from the fuel source. Green wood contains a lot of water and the water in the wood reduces the BTU's.
• Air - Air in the system makes your fire burn hotter. No air kills the fire. Not enough air produces a cool fire which can lead to creosote build-up.
• Starting the Fire - Properly starting a fire is very important.  
• Kindling & Newspaper - The proper way to start a fire is with kindling and newspaper.
• Petroleum Products - Petroleum products produce a fast start fire and may shock-load a chimney. DO NOT START WOOD FIRES WITH PETROLEUM PRODUCTS
• Talk to the Kids - Chamberlain urged the students of the class to bring this program into the schools. By teaching kids, the parents will learn. Kids love to share what they've learned.
• Open a Window to Replace Oxygen - Chamberlain joked, "How many guys in this room have gone home at night; patted the wife on the hind end; and she said, 'I've got a headache'? Has that happened to anybody in the room?"
• One student in the class raised his hand and said, "It's been two weeks!"
• Chamberlain asked, "Do you have a wood stove?"
• The student responded, "NO!"
• "Well, you've got a problem then!" Chamberlain returned with a chuckle.
• One of the first signs of oxygen depravation is a headache, and wood stoves use a tremendous amount of oxygen. Open a window and let some fresh air into the room.
• Removal of Ashes - Use only metal containers to remove your ashes.
• Recognizing a Chimney Fire - Here are some signs:
• Roaring Sound - The fire ring actually rocks the chimney. It sounds almost like a train coming down the tracks.
• Fire Coming Out of the Stack - If it looks different than usual, there may be cause for alarm.
• Creosote - Tell kids and other people there are three different kinds of cresote.
• What Does a Chimney Fire Look Like?
• How Do You Call the Fire Department?
• Does Your Insurance Company Know You Are Using a Wood Burning Appliance?
• Do You Have a Smoke Detector?
• When Was the Last Time the Batteries Were Change In Your Smoke Detector?
• Do You Have a Carbon Monoxide Detector?

 

 

Jim Albert