Why The Chimney Should Cross The Highest Heated Space - Osburn 2200 Installation And Operation Manual

2200 Installation and Operation Manual
Good System Design Inferior System Design
Inside chimneys are preferred because even when Outside chimneys are a problem because
no fire is burning, there is normally upward flow in when no fire burns they will go into cold
the system. backdraft if the stove is installed low in the
house.
8.4.2 WHY THE CHIMNEY SHOULD CROSS THE HIGHEST HEATED SPACE
When it is cold outside, the warm air in the house is buoyant so it tends to rise. This tendency of
warm air to rise creates a slight pressure difference in the house. Called 'stack effect', it produces
a slightly negative pressure low in the house (relative to outside) and a slightly positive pressure
zone high in the house. If there is no fire burning in a heater connected to a chimney that is
shorter than the warm space inside the house, the slight negative pressure low in the house will
compete against the desired upward flow in the chimney.
There are two reasons why the chimney
in the house at right will cold backdraft
when it is cold outside and there is no
fire burning in the stove. First, the
chimney runs up the outside of the
house, so the air in it is colder and
denser than the warm air in the house.
And second, the chimney is shorter than
the heated space of the house, meaning
the negative pressure low in the house
will pull outside air down the chimney,
through the stove and into the room.
Even the finest stove will not work well
when connected to this chimney.
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