Hearth and Home Technologies 823-0170 - Manual (Page 10)

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Page 10 September 1, 2008
Isle Royale Wood Stove
250-5763C
To be sure that your stove burns properly, the chimney draft
(static pressure) should be approximately -.04” water column
(W.C.) during a low burn and -.10” W.C. during a high burn,
measured 6 inches (152mm) above the top of the stove after
one hour of operation at each burn setting.
NOTE: These are guidelines only, and may vary somewhat
for individual installations.
The stove was designed for and tested on a 6 inch (152mm)
chimney, 12 ft.-14 ft. (360-420cm) high, measured from the
base of the stove. The further your stack height or diameter
varies from this configuration, the possibility of performance
problems increases. In addition, exterior conditions such as
roof line, surrounding trees, prevailing winds and nearby hills
can influence stove performance.
A masonry chimney or a listed factory-built UL103 HT Class
“A” chimney must be the required height above the roof
and any other nearby obstructions. The chimney must be
at least 3 ft. (91cm) higher than the highest point where it
passes through the roof and at least 2 ft. (61cm) higher than
the highest part of the roof or structure that is within 10 ft.
(305cm) of the chimney, measured horizontally. See 2-10-3
Rule below.
These are safety requirements and are not meant to
assure proper flue draft.
We recommend using a minimum total system height of 12
ft. (360cm), measured from the flue collar to the top of the
chimney (not including chimney cap).
CHIMNEY HEIGHT REQUIREMENTS / DRAFT
3 ft Min
(91cm)
2 ft Min (61cm)
10 ft Min
(305cm)
2-10-3 RULE
A proper amount of flue draft is required to assure the safe
and efficient operation of the this woodstove. Flue draft is
measured as negative pressure in the chimney. The amount
of negative pressure determines the strength of the draft.
This draft performs two important roles in the operation of
the woodstove. It draws the combustion air into the firebox,
and pulls the smoke out of the chimney.
Three factors work together as a system to create the flue
draft; 1) availability of combustion air; 2) heat generated
from the fire, and 3) diameter and height of the flue system..
Increasing or decreasing any one of them will affect the
other two and thus change the amount of draft in the entire
system.
A source of air (oxygen) is necessary in order for combustion
to take place. The combustion air enters the firebox below
the ash catcher and is directed to the upper front of the fire-
box. These openings are regulated by the Primary Air Slide
Control and Start-up Air Control, (see page 18 for operation
of these controls). It is important to realize that whatever
combustion air is consumed by the fire must be replaced.
If you are using room air, the air is replaced via air leakage
that occurs around windows and under doors, etc. However,
in most newly constructed houses, mobile homes, or even
existing homes that are fitted with tightly sealed doors and
windows, the area from which the combustion air is taken
is relatively air tight. In these cases, an outside air source
must be made available to feed combustion air from outside
the home into the stove. An Outside Air Kit is available as
an option, Part 831-1780. The kit is a requirement for mobile
home installations.
A specific volume of air, determined by the diameter and
height of the chimney connector and chimney, is contained
within the flue system. As heat from the fire enters the flue,
it warms this air causing it to rise. The air moving up the
flue draws smoke and more heated air from the fire with it,
thus establishing draft. The amount of draft depends on the
temperature of the heated air and the volume of air that is
contained in the flue system.
If the fire is difficult to start, and smoke spills out of the door,
or you find it hard to establish and maintain a moderately
high burn rate, then the flue draft is too low and corrective
measures must be taken.
If you still suspect you have a low draft problem, it may be
necessary to increase the volume of air in your flue system.
Since the diameter of your flue system is matched with the
size of the flue collar and should not be changed, the height
of the system will need to be increased. Add chimney a little
at a time until the draft improves, and ensure that the flue
collar and venting section are sealed.
Your local dealer is the expert in your geographic area and
can usually make suggestions or discover problems that will
easily correct your flue draft problem, allowing your wood-
stove and its flue system to operate correctly and provide
safe and economical heat for your home.