4
87D0174
SSTB11 Woodburning Fireplace
OPERATION GUIDELINES
As wood is burned in this fireplace, room air enters the
side vents of the SSTB11 and circulates around the fire-
box. This air circulation cools the firebox and must not be
blocked or restricted in any manner. Blocking the airflow
can cause a fire hazard.
When an AK4 combustion air assembly and a combus-
tion air duct are attached to the connecting point on the
left or right side of the fireplace, combustion air may enter
the firebox through a dampered opening behind the left or
right side brick. This feature is designed for your benefit
to reduce the room air used for combustion and to prevent
excessive loss of heat from the room. When the fireplace
is in use, this damper should be open. When the fireplace
is not in use, the damper should be closed to prevent cold
air from entering the firebox. The combustion air damper
is open when the lever, located on the left and right side
of the firebox near the top of the firebrick, is up and closed
when the lever is down.
Outside air for combustion is optional unless required by
federal, state or local building codes. See the section of
this manual providing the instructions for installation of
the combustion air assembly. The design of the fireplace
allows the routing of the combustion air duct up, down, or
horizontally to obtain the outside combustion air. This per-
mits flexibility in planning your installation. Refer to
Page
19, Figures 24 & 25
for typical installation methods. Re-
view the precautions and recommendations in this manu-
al pertaining to outside combustion air installation.
The fireplace is also equipped with a flue damper, which
must be open when the fireplace is in use. The flue
damper control lever is located inside the fireplace. The
counterweighted damper is operated by simply pushing
up to open or pulling down to close the damper. When
the fireplace is not in use, the damper should be closed
to prevent cold air from entering the chimney as well as
preventing warm air in the room from escaping up the
chimney.
NOTE
: It is normal for a small amount of smoke to be re-
leased from the upper portion of the fireplace the first few
times you use your new fireplace. This results from an oil
residue on the metal. Open a door or window to allow the
smoke to escape.
The grate included with this fireplace helps to appropri-
ately locate and contain the burning wood. Failure to use
this grate may cause overheating of parts of the fireplace
and allow large pieces of burning wood to roll forward out
of the firebox. If the grate becomes warped or damaged, it
must be replaced with grate number 072954 only.
WARNING:
Fireplaces equipped with doors should be
operated only with the doors fully open or doors fully
closed. If doors are left partly open, gas and flame may
be drawn out of the fireplace opening, creating risks of
both fire and smoke.
All fireplace chimneys are in direct contact with cold air
on the exterior of the structure. Consequently, when the
fireplace is not in use, cold air can fall down the chimney
of the fireplace to cool off the fireplace chase. Therefore,
the fireplace chase must be insulated to minimize the risk
of cold air infiltration to the home. Even if the fireplace
chase is adequately insulated, this cannot completely
ensure that cold air infiltration into the structure will be
eliminated. Cold air infiltration is a possibility with any
fireplace or device that freely communicates with the air
on the outside of the structure. Today’s homes are more
energy-efficient and, therefore, better insulated and tightly
constructed. Unfortunately, when air is removed from the
house, as by a bathroom fan, or consumed by a furnace,
additional air is needed to replace the air consumed. Un-
less the additional air is supplied, this can cause a nega-
tive pressure in the home. When this happens, the house
will draw in outside air from the cracks in the windows,
down the fireplace flue or other locations of air leakage in
the home. Because cold air infiltration may be unavoid-
able in some structures, MHSC is not responsible for heat
loss or air infiltration through or around the fireplace.
WARNING: Due to the fact this fireplace has two (2)
openings, it is more susceptible to the adverse effects
of drafts or pressure changes in the room or rooms
it serves. The fireplace should be operated with both
sets of doors closed to prevent smoke or flame spill-
age out of the fireplace openings caused by drafts or
pressure changes. The door should only be opened
during the very brief period to add wood to the fire or
to remove ashes. Refer to
Page 25, Figure 31
In extreme cases when a positive draft is difficult to
achieve, a special glass kit is available which will close
off one side of the fireplace. This special door is inoper-
able once installed, but will create a stronger and more
positive fireplace and chimney draft without affecting the
aesthetics of the see-thru design. This special glass kit is
available through your MHSC dealer. Order SST Special
Glass Kit, pt. no. 060848 or ST36 Special Glass Kit, pt.
no. 061040.
The Problem
Depressurization (negative pressure) is caused by the
interaction of air where small differences in air pressure
between indoors and outdoors (pressure differentials)
amounting to no more than .0001 atmosphere creates a
‘stack effect’ - the tendency for air to rise whenever it is
warmer than the surrounding atmosphere.
The stack effect is the working principle of all chimney
systems. Heated flue gases rise up the chimney and vent
into the atmosphere pulling cooler air behind it to fill the
void. Therefore, when the air is warmer indoors than out-
doors, air tends to flow in through the lower part of the
structure and out through the upper part. Air turnover is
accomplished by infiltration through various openings and
