Because Chimney Sweeping is an industry that not many people know detailed information about, we at JP Chimney Services get a lot of questions from customers. Here are a few of the most frequently asked questions:

Why do I need to get my chimney inspected?

Over time and with use, chimneys can become damaged, causing them to no longer conform to building codes under which they were constructed. Masonry chimneys are exposed to the elements, and therefore deteriorate. Prefabricated fireplaces are highly susceptible to water penetration and misuse.

How often do I need to have my chimney swept?

It all depends on the type of chimney you have, the type of appliance connected to your chimney, and the frequency of that appliance usage. According to the National Fire Protection Association (NFPA), you should have your chimney at least inspected annually. If you have a wood burning stove or fireplace, and you burn more than a cord of firewood a year, it should probably be swept once or twice annually.

Is cleaning the chimney a messy job?

At JP Chimney Services, it’s very important to us to keep your home as clean as possible. We use multiple drop cloths that are laundered regularly at our shop. We also have professional quality HEPA filter vacuums, so the soot in your chimney doesn’t end up blown all over your sofa through the vacuum exhaust!

What is exactly is creosote?

Creosote is actually a flammable tar that can form on the inside walls of your pipes, flue liner and chimney cap from burning wood.

How does creosote form?

Creosote forms when a large amount of smoke exits the wood burning stove and cools off as it enters the pipe and rises up the flue. The smoke actually condenses out as a tar as it cools off in a similar manner as steam condenses out as water.

Can creosote be prevented?

Yes! Since we are all wood burners ourselves, we are strong advocates of burning wood cleanly, safely and efficiently. We own 5 wood burning appliances among us and our family that burn a total of about 20 cords of firewood per year and we have absolutely no creosote problems at all!

How is that possible?

Rather than trying to tell you what you’re doing wrong, I’d rather tell you how we burn wood, virtually creosote-free. To be fair and honest, we do have some creosote that forms on our chimney caps. However, this creosote is only a small amount and is not at all a problem or very dangerous. Inside our chimneys, they are absolutely free of any creosote tar.

So tell me, how do you do it?

I look at four different key factors. I’m not going to say you have to do everything we do, but changing one or two things out of the four can make a huge difference. Some may consider our methods extreme, but there’s simply no denying the results!

The first and most important factor is the dryness of our wood. We like to stack all of our wood into ventilated sheds by the end of March for the following heating season. The reason for this is so that it can dry out properly. One of the biggest causes of creosote problems is from burning wood with a high moisture content. Too much moisture in the wood results in a cooler, smokier fire that just doesn’t perform right. Even if the wood guy says the wood is seasoned, and even if it feels dry to the touch, most of the time we feel it’s not ready to burn yet when it’s delivered because it has way too much water content from rain and ground moisture. When people say the wood is seasoned that only means that it wasn’t cut from a live green tree within at least the past year. We hate tarps because they tend to trap moisture in the wood, they can blow off in the wind, develop leaky holes, and they’re a total pain in the neck to deal with when ice and snow storms come around. By stacking all of our wood into ventilated sheds by the end of March, we are absolutely assured of having perfectly seasoned and dried wood to burn every time!

The second factor is almost as important as the first! We have insulated, properly sized flue liners for all of our wood burning appliance chimneys. This is a huge advantage. Remember, creosote forms by a large amount of smoke cooling off as it rises up the flue. High temp insulation keeps the flue temperature much warmer and also protects the surrounding combustible framing of  our houses from overheating. If a flue liner is too large it can cause the smoke to expand outward and cool off too rapidly. If it’s too small, it can cause the appliance to have smoke spillage problems. A flue liner sized properly to the appliance is best. Sadly, masons are still building beautiful masonry structures with lousy, non insulated, “dinosaur-age” terracotta flue liners. This is the same material they have been using for well over a hundred years! These types of flue liners are difficult to clean and are prone to cracking and creosote problems, especially if they are exposed to the cold weather on the outside of a house. The good news is that most chimneys can be relined with an insulated stainless steel flue liner.

The third factor to look at is our stoves. I have a Vermont Castings 2-In-1 Defiant. This catalytic/non-catalytic stove is a newer design that can actually be burned with or without the catalyst, hence the name 2-In-1. I find it’s easier to get a clean burn with the catalyst than without it. However, that means replacing it fairly often, but there is a pro-rated warranty on it. I consider spending less than $100 per year as part of my heating fuel bill well worth it considering the benefits. Older stoves do not have the clean burn systems that the newer stoves have. Clean burn systems, aka secondary combustion chambers are designed to burn the smoke off when the air intakes are set low. (Remember, creosote forms by an excessive amount of smoke cooling off as it rises up the flue.) This can be overcome somewhat by burning the older stove on a higher air setting all the time, but that can have obvious drawbacks such as shorter burn times and too much heat production at once.

The fourth factor is our burning habits. Smoke is actually a flammable gas that burns at about 1100 degrees. I always strive for a clean burn with virtually no smoke coming out of my chimney. When I get up in the morning, my stove has usually burned down to a bed of embers, but is still giving off some heat. My clean burn method here is to open the stove damper and put some smaller logs on first, then a larger log or 2, but I only fill the stove halfway and set the air intake on high. The reason for this is that if I load the stove completely full, it often produces a larger than necessary amount of smoke because the stove has cooled down somewhat. A lot of smoke not only can produce excessive creosote on the cap, it also can produce irritated neighbors! This is never a good thing! After the fire is well established, I will turn the air intake down to medium setting, but leave the damper open. After breakfast and right before I go to work, I then load the stove completely full and shut the damper, setting the air intake on medium to medium-low. You see, by this time the half load of wood in the stove has turned to hot charcoal embers and is hot enough to start the secondary burn process going after the damper is shut. Alternatively, after the fire is well established from loading the stove halfway, load the stove full at that time, shut the damper, but set the air intake on high. Wait until you get the clean burn, then lower the air intake. I know I’m getting a clean burn by looking at the top of the chimney for smoke or use a catalytic probe thermometer. If you have a non catalytic stove, the procedure is very similar.