4
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Unrestricted permanent fresh air inlet required to draw in outside
air needed for correct operation.
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A barometric damper must be installed to help regulate the draft. A
barometric gives you more control in the “fuel to air” mixture needed
for correct combustion. (See Pg. 8).
3. Ventilation
You MUST replace the air inside your boat at the same rate that the heater is
removing it. The higher the heater’s burning rate, the more air the heater will
require. If the air flow is blocked or restricted, the heater will burn inefficiently,
create soot, blow out and can be a health hazard.
A permanently open fresh air inlet MUST be installed or dedicated to the heater.
This inlet must be at least 3" in diameter. Ducting fresh air to the heater is also
an option. It is important to create and maintain a positive pressure inside the
boat. High winds can draw air out from the boat and thus create a negative
pressure. This condition can result in down drafts. Ensure that when you do
have windows open that they do not create a suction effect in the cabin due to
the window’s position and the wind direction. In a similar way, it is possible for
the air intake on your engine to suck the air out of a cabin if it is not properly
vented.
Your heater is a natural draft appliance and it creates its draft pressure like a
chimney in a wood stove. The rising, heated air in the chimney pulls fresh
air into the heater as it rises up the chimney and exits the flue cap. The
greater the draft pressure, the more able the heater will be to resist strong
winds, overcome flue elbows that inhibit draft and the hotter you will be
able to get your heater without sooting. A CO alarm should be installed in
the boat.
4. How Does the Chimney affect the Heater?
The heater does not create the draft for a natural draft appliance to operate; it
is the chimney that creates the draft for operation. The purpose of a chimney
is to take the combustion products (smoke and gasses) from the appliance to
the atmosphere outside your boat, and at the same time, to draw air in for
