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Maintaining Your Wood Heating System
Maintaining your wood heating system
Wood-heat system maintenance includes simple tasks such as ash removal and glass cleaning, as well as bigger jobs such as chimney cleaning, gasket replacement, repainting and major repairs. Wood-burning systems operate under a variety of conditions during each heating season, and these different conditions create the need for various maintenance tasks. For example, the slower burning needed in fall and spring when heat demand is low, tends to result in more rapid creosote build-up in the flue pipe and chimney. Chimney cleaning is usually needed more often in spring and fall, especially for older appliances that do not burn the wood completely. On the other hand, wood-burning appliances operate closer to their maximum heat output during the coldest winter months which causes stress to parts that are exposed to high heat. Advanced-technology wood heaters have internal parts that wear out because of their exposure to high temperatures. In good quality appliances, any part that can wear due to normal use is replaceable.
One of the best ways to be sure that your wood heating system gets the maintenance it needs is to hire a professional chimney sweep who is trained and certified under the WETT program (or CSIA). A professional sweep will clean the system from top to bottom and report any problems to you. The sweep might suggest that it is time to replace the flue pipes, catalytic combustor, or door gaskets, and will probably be able to do the work for you when the time comes. Your WETT-certified (CSIA) wood heating retailer may also offer sweeping and maintenance services. Here are the most important maintenance tasks to consider as you look over the condition of your wood heating system:
Clean and inspect the chimney and flue pipes
The chimney and flue pipes must be checked regularly until the rate of creosote buildup is determined. Chimney fires usually happen because the user was surprised at how fast the deposits developed. Check the pipes often and clean when the deposits have built up to more than 4 mm (1/8 in.). Older systems that smolder can need cleaning as often as every few weeks. Advanced-technology appliances can operate so efficiently that cleaning is only needed once a year. However, even if you have an advanced stove, never assume the chimney is clean. Check it often to be sure. As maintenance is done, it is a good idea to check the condition of the chimney and flue pipes to see if there is any deterioration. Check the flue pipes for rust that can weaken the joints. Look for corrosion or rust stains on the outer shell of a metal chimney, and check for bulges or corrosion in its liner. When inspecting a masonry chimney, look for black or white stains on the outer bricks, and cracks or missing pieces in the chimney liner. Always check the condition of the chimney in hidden spaces including the attic, wall and chimney chase areas where corrosion and other deterioration can occur. The most thorough cleaning and inspection of the appliance and venting system should be done in the late spring just after the heating season is over. Deposits left in the appliance can combine with the warm humid summer air to cause corrosion of steel parts. Cleaning and inspection in spring will also give you plenty of time to order replacement parts and do any needed repairs before the fall heating season begins. If you see any problems during your cleaning and inspection, have the system thoroughly inspected by a qualified chimney sweep and repaired before continuing to use it.
Check firebricks, baffle plates and catalytic combustors
Cracked firebricks don’t necessarily need immediate replacement, but if bricks start to break up, they should be replaced right away because they protect the steel parts from being damaged by heat. Baffles are steel, ceramic or firebrick plates within the stove that divert the exhaust to take a longer path before exiting at the flue collar. Because of their location and function, baffles can deteriorate with use. Any warping or breakage of a baffle is a sign that it needs replacement. Some appliances have air tubes at the top of their fireboxes that may also deteriorate. It is important to immediately repair any damage to baffles
or air tubes because continued use could do permanent damage to parts that cannot be replaced. Catalytic combustors deteriorate slowly over their expected life span of two to six years. Follow the manufacturer’s instructions for the annual maintenance of the combustor. Visible smoke from the chimney may be the first indication that the combustor has stopped working. To check its function, start a fire and warm the stove
normally. Engage the combustor by closing the bypass damper and set the air control for an extended burn cycle. Wait 15 minutes then go outside to see if there is visible smoke coming from the chimney. If you see smoke, check with your wood heat dealer or chimney sweep on further advice on when to replace the combustor.
Replace door gaskets and other seals
Gaskets and seals are important because they control the location and flow rates of air into the appliance. Leaky seals will reduce the efficiency of the unit. Some gaskets may need replacement as often as once each year, and others may be fine for several years of use. The glass panels in stove and fireplace doors also have gaskets that should be replaced when the door gasket is replaced. All gaskets and seals should be checked at least once a year during a thorough maintenance inspection and perhaps once again during the heating season. You can do a quick check of door gasket seals when the appliance is not operating by closing the door on a thin piece of paper. When the door is latched closed, the paper should be gripped firmly by the door seal. Do this test all the way around the door. If the paper pulls out easily, either the door latch needs adjustment or the gasket needs replacement. To get a good seal with gaskets, the correct size and type must be used. Follow the manufacturer’s instructions for gasket selection and, if possible, go back to the retailer that sold the unit to buy gasket material and glue. Some retailers offer a gasket replacement service in which you bring in your appliance door and the staff installs the correct door and glass gaskets for you.
Maintaining door glass
The door glass in modern wood burners is a transparent ceramic material that can withstand very high temperatures. It is unlikely that the glass will break because of heat, but if it is struck with a hard object, it can break. Always go back to the store where you bought the appliance or to its manufacturer for replacement glass, so you are sure to get the right size, shape and material. Most new appliances have an air-wash system to keep the glass clear, but these systems vary in effectiveness. Some door glass panels stay clear for weeks, while others get hazy within a few days. Wait until the appliance has cooled before cleaning the glass. Usually, a damp cloth or paper towel will remove the ash dust or light stains. To remove darker more stubborn stains, see your stove retailer for the special stove glass cleaner that removes the stains and does not scratch the surface. Apply the cleaner to the cloth, rather than spraying it on the glass to avoid having it drip onto the gasket where it may cause deterioration. Dark streaks forming from the edge of the glass panel are a sign that the door glass gasket needs replacing.
Service fans and other components
Stove, fireplace and furnace fans can pick up dust and hair which can cause wear and reduce their efficiency. Any fan that is used regularly should be cleaned at least once each year. The fan motor may need lubricating and the fan enclosure should be vacuumed.
Maintenance tasks for pellet stoves
Pellet stoves are more complex than wood stoves, with motors, fans, electronic controls and heat exchangers. Most pellet stoves need cleaning every four to six weeks or after having burned about one ton of pellets. This servicing includes cleaning of the firebox walls, heat exchanger, ash pan and burn pot of ash deposits. Clean the hopper of pellet dust, and, in the case of a stove with a gasket on the fuel hopper lid, clear this
area of pellet chips and dust. The venting system may need cleaning each month if a high-ash grade of wood pellets is being burned. Hearth shops offer vacuum cleaners that are specifically designed for pellet stove maintenance. At the end of each heating season a more thorough servicing is needed. The pellet stove installation manual outlines the steps to be followed for this annual service. The venting system is usually cleaned thoroughly and re-sealed at the end of the heating season. Fan and auger motors may need oiling, and deposits should be removed from fan blades. The component compartment of the stove should be vacuumed and the stove re-assembled. Glass and door gaskets should be checked and replaced when required. Many people choose to do the periodic cleanings on their own, while having a qualified technician complete the more complex annual cleaning. The efficient operation and durability of pellet appliances depends on proper servicing periodically during use as well as the major servicing at the end of the heating season.