Optima Installation and Operation Manual
8.4
The Relationship Between the Chimney and the
Because the venting system is the engine that drives the wood heating system, it must have the right
characteristics. The signs of bad system design are cold backdrafting when there is no fire in the
stove, slow kindling of new fires, and smoke roll
two guidelines to follow. First, the chimney should be installed up through the heated space of the
house, not out and up an outside wall. Second, the chimney should penetrate the top of the building
at or near the highest heated space.
8.4.1 Why inside chimneys are preferred
Venting systems that rise straight up from the stove flue collar provide the best performance.
Chimneys that rise inside the warm space of the house tend to provide a small amount of draft
when there is no fire burning. This means that when you light a fire, the initial smoke goes up the
chimney and strong draft builds quickly as the chimney flue warms up. Although they are common in
North America, chimneys that exit a house wall and r
Good System Design
Inside chimneys are preferred because even
when no fire is burning, there is normally
upward flow in the system.
8.4.2 Why the chimney should penetrate the highest heated space
When it is cold outside, the warm air in the house is buoyant
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.
The Relationship Between the Chimney and the House
Because the venting system is the engine that drives the wood heating system, it must have the right
characteristics. The signs of bad system design are cold backdrafting when there is no fire in the
stove, slow kindling of new fires, and smoke roll-out when the door is opened for loading. There are
two guidelines to follow. First, the chimney should be installed up through the heated space of the
house, not out and up an outside wall. Second, the chimney should penetrate the top of the building
r near the highest heated space.
Why inside chimneys are preferred
Venting systems that rise straight up from the stove flue collar provide the best performance.
Chimneys that rise inside the warm space of the house tend to provide a small amount of draft
when there is no fire burning. This means that when you light a fire, the initial smoke goes up the
chimney and strong draft builds quickly as the chimney flue warms up. Although they are common in
North America, chimneys that exit a house wall and run up outside can cause problems.
Inside chimneys are preferred because even
when no fire is burning, there is normally
upward flow in the system.
Inferior System Design
Outside chimneys are a problem
because when no fire burns they will go
into cold backdraft if the stove is
installed low in the house.
Why the chimney should penetrate 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
he 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.
35
Because the venting system is the engine that drives the wood heating system, it must have the right
characteristics. The signs of bad system design are cold backdrafting when there is no fire in the
out when the door is opened for loading. There are
two guidelines to follow. First, the chimney should be installed up through the heated space of the
house, not out and up an outside wall. Second, the chimney should penetrate the top of the building
Venting systems that rise straight up from the stove flue collar provide the best performance.
Chimneys that rise inside the warm space of the house tend to provide a small amount of draft even
when there is no fire burning. This means that when you light a fire, the initial smoke goes up the
chimney and strong draft builds quickly as the chimney flue warms up. Although they are common in
un up outside can cause problems.
Inferior System Design
Outside chimneys are a problem
because when no fire burns they will go
into cold backdraft if the stove is
installed low in the house.
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
he 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
