Wood burning stoves offer heating alternative

Tuesday, December 1, 2015

As temperatures continue to drop, wood burning stoves will get more and more action.

The stoves are an economically friendly solution to heating the house, but without proper operation, the result could be more costly than just a high natural gas bill. The majority of fires involving wood stoves are a direct result of improper operation.

The Oklahoma Cooperative Extension Service offers guidelines from everything from starting a fire to ash removal to ensure a warm and uneventful winter.

Once the wood stove is installed correctly, open the damper completely. Kindling or paper should be placed over the entire bottom of the box, which will achieve an evenly burning fire. Use of flammable liquids to start a fire can result in explosions and uncontrolled fires.

Slowly add seasoned dry wood to lit kindling, being careful not to smother the fire with too much wood. Once the fire is burning briskly, adjust the draft controls to maintain the desired heat output.

Stoves are built differently and should be treated accordingly. New cast-iron parts need to be “seasoned” and should have only small fires built the first few times to avoid cracking. Stoves without an ash pit should have two inches of sand insulating the bottom of the firebox to prevent overheating and an eventual burnout.

As the fire calms and it is time to refuel, the draft controls should be opened for a couple minutes for the stove pipe and flue to heat up.

“This will increase the draft and should prevent smoke from coming out into the room when the stove door is opened,” said Scott Frazier, associate professor of biosystems and agricultural engineering at Oklahoma State University’s Division of Agricultural Sciences and Natural Resources.

Wood should then be added and the draft left open until the new wood catches fire. The new wood will require readjustment of the controls to the desired setting. Once the desired setting is reached, we cannot let our guard down, said Frazier.

“One of the most common causes of wood stove-caused home fires is leaving the fire untended,” Frazier said. “Whenever someone must leave the house while a fire is burning, take the necessary precautions to prevent the possibility of an uncontrolled fire.”

Frazier said the worst danger in leaving a stove burning is the fire could burn out of control and overheat the stove, or a spark will escape through a draft inlet. Opening the stove pipe damper and closing the air inlet dampers can avoid both of these scenarios.

Older stoves which are not airtight are much more difficult to control as they have their own hidden air intakes. The best thing to do is to make sure the fire has died down before leaving the house.

“Allowing a large fire to burn unattended in such a stove is dangerous,” Frazier said.

Any combustible material should be at least three feet clear of the stove.

“It’s easy to overlook such thinks as clothes drying, kindling, newspaper, carpets or logs left to dry under the firebox,” Frazier said. “All of these things can catch fire from intense heat radiation.”

Upon returning to the house, the dampers should be opened and the fire stoked. The fire should burn briskly for a while to get it hot and burn off some of the creosote. Creosote is a tar that forms on the inside surfaces of the stove and chimney. This unwanted product comes from smoke and water and mainly occurs when using green wood or fires that are not hot enough (below 250F).

Creosote is very flammable and if ignited could cause a damaging chimney fire. Chimney fires are sometimes hard to detect but may make a loud, continuous “whoshing” sound. If a chimney fire is detected – shut off all air supply to the fire (glass doors, vents, etc.), and safely extinguish the main stove fire. A fire extinguisher should be located near the stove within easy reach.

Only multipurpose dry chemical extinguishers should be used, as a pressurized water extinguisher could result in severe stove damage or even an explosion. As always, if things are getting out of control – call the fire department.

To avoid creosote buildup, the best method is to keep the fire burning with dry, well-season wood, which will keep flue temperatures above 250 degrees. However, this preventative measure may be uncomfortably warm for some people as it produces a continuous amount of heat.

“Another alternative to help reduce creosote buildup is to deliberately have a hot fire for 15 to 30 minutes each day,” said Frazier. “This will tend to burn off creosote in small amounts to reduce buildup problems.”

No matter the method chosen to reduce buildup, inspection of all stove pipes and flues should happen regularly, especially during the first wood burning season. A simple method of checking stove pipes is to tap on the pipe with a metal object. The sound will change from a “ping” to a dull “thud” as creosote builds up on the inside of the pipe.

A flashlight can be lowered down a chimney flue to see any buildup. Frazier said 110-volt electric bulbs should not be used for this unless the bulb is protected in a wire cage. Mirrors also can be used, in some cases, to look up the chimney from inside the house.

“Ideally, the chimney and stove pipe should be inspected once a month during heating season,” Frazier said. “If the inspection indicates significant creosote buildup, then the chimney should be cleaned.”

While ash buildup is typically not a major problem, a stove that is functioning under normal heat output under round-the-clock operation will need to have the ashes removed once every week to 10 days.

When removing ashes, keep in mind that they may still be hot and should not be shoveled into a paper bag, cardboard box, plastic container or any other combustible material.

“There are many cases of home fires which have started when hot embers in disposed ashes ignited the combustible container in which they were placed,” said Frazier. “Always remove and store ashes in a noncombustible container, which is stored on a noncombustible floor or on the ground, well away from combustible materials, until final disposal. Also, be careful about dumping the ashes from these containers as field fires have been started from ashes that were several days old.”

Everyone is encouraged to use the disposed ash as a fertilizer as it is very beneficial. Simple maintenance and proper usage of a wood burning stove will result in a warm and cozy winter, without the hundreds of dollars lost on gas and propane.