Page 145 - Boiler plant and distribution system optimization manual
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130 Boiler Plant and Distribution System Optimization Manual
Description umes of high temperature exhaust gasses. Years
When a boiler isn’t firing, a great deal of en- ago, slots were cut in the stack and metal damp-
ergy can be lost up the stack due to the chimney ers inserted, but these often were unsatisfactory.
effect when the lighter hot air formed in the boil- A modern adjustable design has been developed,
er internals and in the hot stack pull cold air in a special exhaust gas buffer that has shown good
through the boiler. This situation is most common results (Figure 10.29).
on atmospheric burner units, but may be present
on some older equipment too. Advantages/disadvantages
A damper automatically closes off the stack This inexpensive device can slow down the
when the boiler isn’t firing, holding the heat in escape of hot gases up the stack. It can also be
the boiler (Figure 10.28). adjusted to a specific location.
Advantages/Disadvantages
Stack dampers have full safety approval and
should be installed to curb this unnecessary loss.
10. SLOW DOWN ExHAUST FLOW
Cost
Low
10. Savings
Moderate to low
Description
In many cases the size of stacks and exhaust
systems is excessive allowing unrestricted and
often excessive negative draft “draw” to exist.
Oversized exhaust systems offer little resistance
Figure 10.29—A fixed damper buffers high velocity
to the varying conditions of stack “draw” and
escape of flue gas without limiting cross sectional
cause excess air to be pulled into the burner as
area of stack
well as aid the unrestricted escape of large vol-
11. WIND DEFLECTOR FOR
BOILER ROOM VENTS
Cost
Small, basically a design consideration
10. Savings
Moderate
10. Description
Boiler rooms are required to have a certain
square footage of free ventilation access per boil-
er horsepower. In some locations wind driven air
pressure can cause draft control problems. One
Figure 10.28—Stack dampers used to block heat loss-
has only to try to walk into a strong wind to grasp
es.
