Woodburning 101 | Don't forget to clean the screen

Sound familiar? My stove burned great after the chimney was swept but gradually it got "sluggish". The wood didn't start as quickly, it wouldn't burn as hot as it used to and smoke started coming out the door when you first started a fire or opened it to load more wood. These are all classic signs of a plugged chimney cap. It doesn't have to be completely blocked to cause these symptoms, just restricted enough by a build up of creosote, a by-product of the un-burned gases and moisture driven out of the wood during the burning process. We've received a string of phone calls lately from people with these symptoms and 99% of the time a plugged chimney cap is the cause. There could be other issues such as a down-draft problem or wet wood, but in the vast majority of cases it's the spark arrestor screen in the cap that's the culprit. What causes the cap to become blocked by creosote? Burning wet wood, either not seasoned long enough or not stored properly so it becomes wet from rain or snow, is one factor. Wood should, at the very least, be under 20% moisture content to burn properly. It takes energy to evaporate the moisture out of the wood and carry it up the chimney. This is energy that would otherwise go towards creating heat, so wet wood may burn but it won't give you the heat it should. The combination of moisture and un-burned gasses then goes up and condenses on the cooler chimney walls and screen in the cap, building up a layer of creosote. How often should you expect to have to clean your chimney and spark arrestor screen? The answer is "that depends". The general rule of thumb is that you should have your chimney swept at least once a year. This can vary greatly, however, depending on the moisture content of your wood and how you burn your stove. If you load your stove with wood and then close it down to a low burn constantly you can expect to have to clean your chimney and cap much more often than if you burn your stove hot on a regular basis with the air control open for about 20 minutes. Just make sure your chimney is clean beforehand if you haven't been doing this. You may need to clean your screen much more often than you need to clean the whole chimney. In some cases you may be able to go a year between cleanings, in others it can become plugged in as little as a week. It all depends on the condition of your wood and your burning habits. You can clean the chimney and screen yourself! If you're comfortable getting up on your roof a handheld wire brush works well for the screen. For the whole chimney, we carry a full line of chimney cleaning brushes and rods. We also do chimney sweeps in our local area around Grass Valley and Nevada City, CA. Just call our offices M-F 9-5 or Sat 10-2 to schedule a complete chimney and stove cleaning-530-265-8618.