Vermont Casting 1945 Draft Management, Steel Chimney, Indoor/Outdoor Location, Flue Sizing

Page 25

Defiant Woodburning Stove

Draft Management

A stove is part of a system, which includes the chimney, the operator, the fuel, and the home. The other parts of the system will affect how well the stove works. When there is a good match between all the parts, the system works well.

Wood stove or insert operation depends on natural (unforced) draft. Natural draft occurs when the smoke is hotter (and therefore lighter) than the outdoor air at the top of the chimney. The bigger the temperature difference, the stronger the draft. As the smoke rises from the chimney it provides suction or ‘draw’ that pulls air into the stove for combustion. A slow, lazy fire with the stove’s air inlets fully open indicates a weak draft. A brisk fire, supported only by air entering the stove through the normal inlets, indicates a good draft. The stove’s air inlets are passive; they regulate how much air can enter the stove, but they don’t move air into it.

Depending on the features of your installation - steel or masonry chimney, inside or outside the house, matched to the stove’s outlet or oversized - your system may warm up quickly, or it may take a while to warm up and operate well. With an ‘airtight’ stove, one which restricts the amount of air getting into the firebox, the chimney must keep the smoke warm all the way to the outdoors in order for the stove to work well. Some chimneys do this better than others. Here’s a list of features and their effects.

Masonry Chimney

Masonry is a traditional material for chimneys, but it can perform poorly when it serves an ‘airtight’ stove. Masonry is a very effective ‘heat sink’ - it absorbs a lot of heat. It can cool the smoke enough to diminish draft. The bigger the chimney, the longer it takes to warm up. It’s often very difficult to warm up an outdoor masonry chimney, especially an oversized one, and keep it warm enough to maintain an adequate draft.

Steel Chimney

Most factory-made steel chimneys have a layer of insulation around the inner flue. This insulation keeps the smoke warm. The insulation is less dense than ma- sonry, so a steel chimney warms up more quickly than a masonry chimney. Steel doesn’t have the good looks of masonry, but it performs much better.

Indoor/Outdoor Location

Because the chimney must keep the smoke warm, it’s best to locate it inside the house. This uses the house as insulation for the flue and allows some heat release into the home. An indoor chimney won’t lose its heat to the outdoors, so it takes less heat from the stove to heat it up and keep it warm.

Chimney Height

The common wisdom tells us that a taller flue draws better than a short one. This isn’t necessarily so. If a chimney is tall enough to meet the safety requirements of the 2/3/10 foot rule, then adding more height isn’t the right answer to a draft problem. In fact it could make the problem worse, by adding more mass to the chimney system, which the smoke must warm up, at the far end from the heat source (the stove). Don’t make a chimney taller unless you must to meet the safety rules, or un- less there’s some nearby feature causing a downdraft. Even then, there are downdraft-preventing chimney caps available, which are probably the smarter choice.

Flue Sizing

The inside size of a chimney for an ‘airtight’ stove should match the size of the stove’s flue outlet. When a chimney serves an airtight stove, more is not better; in fact, it can be a disadvantage. Hot gases lose heat through expansion; if we vent a stove with a six-inch flue collar (28 square inch area) into a 10 x 10” flue, the gases expand to over three times their original size. This cools the gases, which weakens draft strength. If an oversized flue is also outside the house, the heat it absorbs gets transferred to the outdoor air and the flue usually stays cool.

It’s common for a masonry flue, especially one serving a fireplace, to be oversized for the stove. It can take quite a while to warm up such a flue, and the results can be disappointing. The best solution to an oversized flue is an insulated steel chimney liner, the same diam- eter as the stove or insert’s flue outlet; the liner keeps the smoke warm, and the result is a stronger draft. An uninsulated liner is a second choice - the liner keeps the smoke restricted to its original size, but the smoke still must warm up the air around the liner. This makes the warm-up process take longer.

Pipe & Chimney Layout

Every turn the smoke must take as it travels to the chimney top will slow it down. The ideal pipe and chim- ney layout is straight up from the stove, to a completely straight chimney. If you’re starting from scratch, use this layout if possible. If the stovepipe must elbow to enter a chimney, locate the thimble about midway between the stove top and the ceiling. This achieves several goals: it lets the smoke speed up before it must turn, it leaves some pipe in the room for heat transfer, and it gives you long-term flexibility for installing a different stove without relocating the thimble.

30001693

25

Page 24 Page 26
Image 25
Page 24 Page 26
Contents Defiant Save These Instructions for Future Reference WelcomeInstallation Accessories Table of ContentsStory of the Defiant Defiant, Model SpecificationsOutside Air InstallationChimney Height Masonry Chimneys What Kind of Chimney to UsePrefabricated Chimneys Chimney SizeSingle-wall Chimney Connectors Chimney Connector GuidelinesSecuring the Single-wall Connector to a Masonry Chimney Freestanding InstallationsAbove the Fireplace Fireplace InstallationsWall Pass-Throughs Through the FireplaceFloor Protection Floor Protection for Fireplace InstallationSafe Ways to Reduce Clearances Keep the Stove a Safe Distance from Sur Rounding MaterialsWall Shields Fireplace and Mantel Trim Clearances Fireplace and Mantel Trim ShieldsStove Clearance Unprotected Surfaces Protected Surfaces Defiant Clearance ChartUnprotected Surfaces Protected Surfaces Defiant Clearance DiagramsStove Heat Shields Defiant With Rear Heat Shield only Distance from the Center of the Flue Collar to the WallSet Up Your Stove AssemblyInstall Stove Legs Install the Optional Bottom Heat ShieldDefiant Controls OperationDamper Directs Air Flow Within the Stove Single Air Control Regulates Heat Output and Burn TimeTwo Ways to Add Fuel Andirons Help Protect the Glass Infra-Red Reflective Glass Panels For Clear Fire ViewingBurn Only High-Quality Wood Surface Thermometer is a Valuable Guide to OperationDefiant Control Settings Use the Air Control Settings that Work Best for YouHigh-Efficiency Wood Burning With Catalytic Combustion Starting and Maintaining a Wood Fire Conditioning Your StoveAdd larger pieces of wood as the fire begins to burn Refuel While the Embers Are Still HotAsh Disposal Steel Chimney Draft ManagementIndoor/Outdoor Location Flue SizingSingle Venting Draft TestingCreosote FuelConclusion Negative PressureMaintenance Adjust the Damper as Needed How to Adjust the Door LatchesCheck the Operation Primary Air Shutter Tighten the Damper Handle as NeededWhen to Suspect a Combustor Problem Inspection and CleaningRemoving and Cleaning the Combustor Catalytic ElementRemove the bricks and the brick retainer 30001693 Replace the Stove Gaskets as NeededAdjust the Door Latch If Necessary Annual MaintenanceChimney System Permanent Defiant GasketsAppendix Catalytic Combustor For a fireplace Appendix Chimney and Fireplace HazardsDefiant Woodburning Stove Defiant Woodburning Stove Model Shell Enamel Parts Defiant Color Warranty CFM Corporation

1945 specifications

Vermont Casting, founded in 1975, quickly established itself as a leader in the cast iron stove industry. However, the reference to 1945 in relation to Vermont Casting might allude to the beginnings of the American hearth industry post-World War II. In this pivotal period, the demand for home heating solutions soared, setting the stage for innovations in wood and gas stoves that would shape future designs.

Vermont Casting made a name for itself through a commitment to craftsmanship and durability. The company utilized high-quality cast iron, renowned for its excellent heat retention and even heating properties. This robust material allowed stoves to radiate warmth long after the fire had extinguished, making them an efficient choice for home heating.

One of the standout features of Vermont Casting stoves is their unique design which blends functionality with aesthetic appeal. The company offered both traditional and contemporary styles, appealing to a wide range of consumer tastes. With elaborate decorative patterns and a classic look, Vermont Casting stoves became a centerpiece in many homes, adding warmth not just through heat but also through design.

In terms of technology, Vermont Casting pioneered advancements in combustion efficiency. Their stoves often feature secondary combustion systems that ensure the complete burning of wood, which helps reduce smoke emissions and maximizes heat output. This not only complies with stringent environmental regulations but also makes their products eco-friendly.

Another notable characteristic of Vermont Casting stoves is their versatility. The company produces a range of models that cater to different fuels, including wood, gas, and pellets. This flexibility allows homeowners to choose the best heating solution for their specific needs and preferences.

Vermont Casting also places a strong emphasis on user comfort and ease of use. Many models come equipped with features like airwash systems for cleaner glass, lever handles for easy door operation, and ash pans for convenient cleanup. These thoughtful details enhance the overall user experience, making heating homes more efficient and enjoyable.

As the company has continued to innovate, it has remained committed to sustainability, focusing on creating products that are not only effective but also environmentally responsible. Vermont Casting's dedication to quality, technology, and design has cemented its status as a trusted name in the hearth industry, making it a preferred choice for consumers looking for both performance and style in their heating solutions.
Top Page Image Contents