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Vermont Castings  •  Dauntless FlexBurn Installation Manual_R8  •  2020 - ___ •  11/21

14

3-90-586000i

Chimneys & Venting 

A. Venting & 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 exhaust 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 hot gases rise through the chimney they provide 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 stove’s exhaust 

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.

Draft, Chimney Height & Performance

This appliance was tested for emissions on a 15 foot chimney, 

using  a  combination  of  single  wall  chimney  connector  & 

insulated class A pipe. The unit requires a draft between .03 

and .065 in of H2O. The draft measurement should be taken 

with an active fire, the damper closed and the air control at 

the maximum setting. If the draft is below .03 in of H2O, the 

unit may have issues operating with the damper closed and 

may back-puff into the room on lower burn settings. If the 

draft of the chimney system is too low, additional vertical 

height should be added to the system or the number of 

elbows/tees in the system should be reduced. The venting 

system should have no more than a total of 180° of turns (2 

x 90° elbows, 4 x 45° elbows or any combination). Two 45° 

elbows create less draft reduction than a single 90° and can 

be substituted for installations with low draft. Tall chimney 

systems, particularly internal Class A systems may generate 

draft which is well above 0.65 in of H2O. In that case, the 

unit may experience short burn times, difficulty controlling 

the burn rate of the stove and the potential for overfiring. In 

the past, stack dampers could be recommended in these 

installations, but manufacturers are no longer permitted to 

specify these on EPA Certified models. The chimney system 

should be carefully reviewed and draft tested (if possible) 

prior to installation of this unit.

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 chimney gases 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 chimney warm. 

The insulation is less dense than masonry, 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.

Single Venting

Each ‘airtight’ stove requires its own flue. If an airtight stove is 

vented to a flue that also serves an open fireplace, or a leakier 

stove, it’s easier for the chimney draft to pull air in through 

those channels and performance of the stove suffers. Imagine 

a vacuum cleaner with a hole in the hose to understand the 

effect here. In some cases the other appliance can even cause 

a negative draft through the stove, and result in a dangerous 

draft reversal.

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 faster as they travel slower 

through a chimney; if we vent a stove with a six-inch flue collar 

(28 square inch area) into a 10 x 10" flue, the gases slow to 

one third their original speed. This allows the gases to cool 

more rapids, 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 is 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 diameter as the stove or inserts flue 

outlet; the liner keeps the exhaust warm, and the result is a 

stronger draft. An non-insulated liner is a second choice - the 

liner keeps the exhaust restricted to its original size, but the 

hot gases still must warm up the air around the liner. This 

makes the warm-up process take longer.

Содержание Dauntless FlexBurn

Страница 1: ...the vicinity of this or any other appliance Do not over fire If appliance or chimney connector glows you are over firing Over firing will void your warranty Comply with all minimum clearances to combu...

Страница 2: ...ations 3 E Non Combustible Materials 4 F Combustible Materials 4 G California 4 2 Getting Started A Design and Installation Considerations 5 B Fire Safety 5 C Negative Pressure 5 D Tools And Supplies...

Страница 3: ...6 Inch 152 mm Firebox Size 1 8 cu ft Outside Air Size 3 Inch Recommended Length 16 Inch Max Wood Length 18 Inch Fuel Orientation East West Fuel Seasoned Cordwood 20 moisture or less Weighted average...

Страница 4: ...r surfaced with any of the following materials Wood Compressed Paper Plant Fibers Plastic Plywood OSB Sheet Rock drywall Any material that can ignite and burn flame proofed or not plastered or non pla...

Страница 5: ...hould be given serious consideration 1 Install at least one smoke detector on each floor of your home to ensure your safety They should be located away from the heating appliance and close to the slee...

Страница 6: ...duct work and air handler joints and seams taped or sealed Basement installations should be avoided Reciprocating saw Framing material Pliers High temp caulking material Hammer Gloves Phillips screwd...

Страница 7: ...e with proper clearance Chimney meets recommended height requirements Minimum 16 Feet Roof flashing installed and sealed Terminations installed and sealed Clearances Combustible materials not installe...

Страница 8: ...lass surface Door opening width 24 5 8 625 mm 17 1 2 445 mm 16 3 8 416 mm 18 7 16 479 mm 23 1 16 586 mm 25 3 4 654 mm 25 5 8 651 mm 25 3 4 654 mm 13 3 8 340 mm 27 686 mm 22 5 8 575 mm Figure 3 2 Side...

Страница 9: ...ingle wall pipe 1 6 0 0 m m 8 1 0 m m 9 3 1 m m 1 4 6 7 m m 4 5 7 m m f r o n t d o o r o p e n i n g CANADA Figure 3 7 457MM FRONT DOOR OPENING 203MM 1114mm minimum 1254mm minimum 203MM Must extend 5...

Страница 10: ...Pipe 10 26 1 2 14 For Factory Alcove 6 diameter listed Double wall air insulated connector pipe with UL103 HT listed factory built Class A Chimney or Masonry chimney Maximum depth Alcove shall be no m...

Страница 11: ...20 Figure 3 13 Disclaimers Extended floor protection may be required for shallow installs follow floor protection requirements Full insertion installation may not allow use of the top load door depen...

Страница 12: ...chimney should Install through the warm space enclosed by the building envelope This helps to produce more draft especially during lighting and die down of the fire Penetrate the highest part of the r...

Страница 13: ...g the diameter of the chimney can affect draft and cause poor performance It is not recommended to use offsets and elbows at altitudes above 4000 feet above sea level and or when there are other facto...

Страница 14: ...d in these installations but manufacturers are no longer permitted to specify these on EPA Certified models The chimney system should be carefully reviewed and draft tested if possible prior to instal...

Страница 15: ...ys Chimney The chimney can be new or existing masonry or prefabricated and must meet the following minimum requirements specified in Section 4B C Chimney Systems Prefabricated Metal Chimney Must be mi...

Страница 16: ...lumber to fit into wall opening Inside opening of frame should be no less than 14 x 14 356 mm x 356 mm Figure 4 4 Attach the wall spacer to the chimney side of the frame 5 Nail the frame into the wal...

Страница 17: ...e 6 152mm UL103 HT WARNING WARNING Asphyxiation Risk DO NOT CONNECT THIS APPLIANCE TO A CHIMNEY FLUE SERVICING ANOTHER APPLIANCE DO NOT CONNECT TO ANY AIR DISTRIBUTION DUCT OR SYSTEM May allow flue ga...

Страница 18: ...ll the Bottom Heat Shield NOTE TheBottomHeatShieldisrequiredinmostinstallations Refer to Floor Protection in the Dimensions and Clearances Section of this manual for further details 1 Align the bottom...

Страница 19: ...heavy stove gloves available near the stove Have special safety accessories e g Child Guard Screen available for use if small children will be in the home Fire Risk Do not leave the fire unattended wh...

Страница 20: ...e wall or flooring in your home 1 Remove all materials from packing box 2 Using a 2 Phillips screw driver attach the flex adapter to the appliance using 4 screws Figure 5 8 5 9 3 Floor Rear Installati...

Страница 21: ...rk Metalbestos DS or Security DL double wall connector or any listed double wall connector pipe 5 In Canada this appliance must be connected to a 6 152 mm factory built chimney conforming to CAN ULC 6...

Страница 22: ...mportant operating and maintenance instructions included Leave this manual with party responsible for use and operation Read understand and followtheseinstructions for safe installation and operation...

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