Heating Help

Your current chimney flue may be showing signs of deterioration, such as a hairline crack in the flue, missing mortar between the clay flue tiles, or you may not have a flue at all. Chimney deterioration can cause dangerous combustible gases, such as carbon monoxide, to pour into your living space. Putting any chimney liner down your flue will not solve the problem. Understanding your appliances’ capacities and fuel type, as well as understanding the different types of chimney liners, can result in a safe and efficient way of venting.

Chimney Liner Sizing

Choosing the proper size chimney liner is the most important part when determining which chimney liner is right for you. Choosing a liner that is too small can cause a few problems including poor drafting and condensation issues. Choosing a liner that is too large can cause excessive creosote buildup, as well as wasting fuel from over-drafting.

To figure out which size liner is best for your appliance, start by understanding what fuel you are using. With a wood-burning or coal-burning stove this is easy. The size of the exhaust hole on the top or back of the unit will dictate the diameter of the chimney liner. When sizing a gas- or oil-fueled appliance, a little more information is needed. For a gas appliance you need to know the BTU capacity, the lateral length from the appliance to the chimney, the height of the chimney, and its efficiency rating. Sizing an oil-fueled appliance is similar. You will need to know the gallons per hour firing rate, the height of the chimney, the lateral length from the appliance to the chimney, and the steady-state efficiency rating. You can also connect two or more appliances within the same chimney liner by adding the capacities together and following those same steps. With this information, you can get a recommendation from a venting professional as to what size chimney liner you will need.

Types of Chimney Liners

Once you know the appropriate size of your chimney liner, the next thing you’ll want to know is the different types of chimney liners that will be compatible with your fueling type.

Types of Chimney Liners:

·         316TI Flexible Stainless Steel Chimney Liner:

o   A unique titanium alloy designed to resist flue acids and the extreme stresses of hot and cold cycles. It can withstand multiple heating cycles up to 2100 degrees.              Intended Fuel: Wood, Coal, Low efficient Oil and Gas, and Pellet appliances

·         AL29-4C Flexible Stainless Steel Chimney Liner:

o   Intended for use with HIGH EFFICIENCY GAS, OIL, and CORN burning appliances. The flue gases from these appliances are cooler and create exceptionally high amounts of moisture which in turn promotes formation of an especially corrosive acid.         Intended Fuel: High efficient Gas, Oil, and Corn appliances

·         304L Rigid Stainless Steel Chimney Liner:

o   A smooth interior wall allows the liner to vent without the turbulence that the flexible liners produce. Strong 24-gauge steel makes for a long-lasting, easy-to-clean liner.  Intended Fuel: Wood, Pellet, Low efficient Oil, and Gas appliances

·         316L Rigid Stainless Steel Chimney Liner:

o   Tougher against corrosion than the 304L.  The 316L can withstand high temperatures as well as corrosive acids found by higher-efficiency appliances.  The smooth interior wall also gives the liner better draft and reduced turbulence.  Intended Fuel: Wood, Coal, Pellet,  Gas, and Oil appliance

Do I Need To Insulate My Chimney Liner?

Adding insulation around the flue liner will help your chimney liner vent to its utmost efficiency. This will help the liner retain the heat inside the flue and keep the flue from compensating. Insulation will also cut down on the buildup of creosote inside the flue. When the flue gases start to cool down, the byproduct is creosote. Creosote is inevitable, but insulating the liner cuts down on the buildup of creosote. There are various types of chimney-liner insulation. The insulation blanket wrap and the vermiculite pour-down mixture are the most common to maintain the UL listing of the chimney liner. 

(Our friends at Rockford Chimney Supply provided this important information. You can reach them at 1-866-708-2446, or visit their website.)