"Taking care of the fireplace"
Column #871 11/05/11
On The Level
Q. There was a fireplace in our house when I was growing up and my Dad burned fires a lot during winter and other than watching the fires I didnít pay attention to it. After I moved out and got married I lived in apartments and condos that didnít have fireplaces but now we have a house with one and I hear different things about using and cleaning it. What should I do and not do?
A. Fireplaces inside of modern homes are a total anachronism and just donít make sense. However, weíre not going to easily get rid of something that appeals to some deep, almost primordial comfort and safety gene lodged deep in our brains that loves the look and warmth of a dancing flame on a cold winterís eve. But since you are starting a fire with an open burning flame inside of your house which, if handled improperly, could cause a major disaster there are a few things you need to know.
The design of fireplaces remained the same over the centuries until the time of the American Revolution when two Americans revolutionized the design and performance of the till then traditional fireplace. A New Englander named Benjamin Thompson came up with the smoke shelf and angled sides which greatly improved the draft or draw of the fireplace--keeping the fire inside of the firebox
Ben Franklin invented the damper which controls what the fireplace did when it isnít burning and to some degree while it is. Open the damper and air can go up the chimney. Close it and it stops chimney air movement. Thatís important because if you are heating your house with a furnace or heat pump and inadvertently leave the fireplace damper open you will be venting your expensive heat up the chimney and out of the house 24/7 until you remember to close it. I often see fireplaces with dampers left open and I can tell by the amount of dust I see on the damper plate that it has been open for a long while pulling air from the house. Also, depending upon atmospheric conditions, air can come down the chimney and into the house with the damper open. Frequently in summer the fireplace can smell like burned wood and stale smoke after it rains. The house is pulling air down the chimney and with it the chimney smell.
The rules for safely enjoying your fireplace are pretty simple. First only use cured, dried hardwoods for firelogs. Good firewood is available all over the place but just make sure there arenít softwoods like pine mixed in. Pine will yield a lot of creosote when it burns and that will soil the chimney much faster than hardwoods will. Burning wood can pop and throw burning embers into the room so have a fireplace screen in front of the fire while itís burning.
When getting ready to build a fire take a flashlight and get on your knees, open the damper and look up the chimney to see if anything is blocking it. There is a bird called a chimney swift that builds nests in chimneys and other animals can fall into the chimney an expire. These are unpleasant surprises that can be greatly reduced by the addition of a rainhood with a bird screen at the chimney top. If you don't have one, get one.
Set the fire small and to the back of the firebox. I see fireplaces all the time where I can tell the firestarter crammed firewood into the fireplace, crumpled a bunch of newspaper and set a match to it. The fire erupts and since the natural draft hasnít started yet the fire burns out of the firebox and smoke stains the area above the fireplace or they didnít ensure the damper was open. Itís a mess. And expensive to clean up.
Iím routinely asked how often should the chimney be cleaned. I respond that itís a function of use. If you burn a couple of cords of wood a winter then closer attention has to be paid to cleaning than the normal fireplace usage which tends to be major winter holidays, anniversaries if they occur in winter and Super Bowl. Thatís about four or five times a year and at that level of usage you can go quite a while between cleanings. I tell folks to again climb down on their knees and using a flashlight, open the damper and look at the chimney lining. If you can see a shiny crust of soot and creosote forming then itís time to call the chimney sweeps.
The main purpose of keeping the chimney clean is to prevent a chimney fire. A chimney fire can occur when the build up of creosote on the flue wall gets to the point where it can ignite and burn. When it does it is very dramatic. It sounds like a jet engine and you canít control it. It hurls burning bits of creosote up and out which land on the roof shingles and the rood catches fire. Iíve only seen one in action and it got my attention. The fire department gets called and they put it out but not before the temperatures inside the chimney get above 2000ļF and when itís all said and done the chimney is ruined and must be rebuilt.
Old fashioned fireplaces had ash dumps of the floor of the firebox where you could push the ashes but most modern ones donít which means you have to take them out yourself. Be very careful doing that and place the ashes in whatever you put them in away from the house and not on a wood deck. You might think the fire is out but there is often a spark left and that can cause trouble. Itís happened to me. Wait a least a day before you close the damper as there may be residual embers in the ashes and smoke will set off your smoke alarms. Donít forget to close that damper when itís time. And finally, donít store firewood against the house-- it can attract termites and provide dwelling for other unwelcome critters.
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