Carlin Component Testing - Manual (Page 8)

Carlin U – Residential Oil Burners – Page 25
As air temperature changes, so does
the CO
2
and O
2
• Once an oil burner is setup, the fan always
pulls through about the same volume of air
(cfm) regardless of air temperature. (Air
fl ow will be reduced if the overfi re pressure
increases due to a dirty heat exchanger,
or if the inlet air is blocked or the blower
blades are dirty or linted.)
• Air density changes with temperature. The
colder the air, the more dense the air.
• The blower pulls in a constant volume of
air. If the air density changes, weight of
air (pounds) entering the burner changes.
When the air is colder (heavier), more
pounds of air enter. When the air is warm-
er (lighter), less pounds of air enter.
• When combustion air comes from inside,
it comes in at room temperature, so the
temperature of the air doesn't change
much throughout the year. But when air is
ducted directly from outside, it isn't heated
much before it reaches the burner. It comes
in pretty close to the outside temperature.
In the summer, it could come in at 90°F or
higher, while coming in at below -20°F in
the winter. The air temperature difference
between summer and winter could easily be
100°F for some areas.
• The table at left shows the change in the
amount of air (pounds) as the temperature
of the air changes.
• Take the air temperature into account
when you set up a burner with ducted com-
bustion air.
• % CO
2
rises as air temperature rises.
• % CO
2
drops as air temperature drops.
If you don't consider this, burner combus-
tion can become very poor as air tempera-
ture changes.
• Refer to the setup temperature chart at left
for suggested setup values based on enter-
ing air temperature.
Combustion air temp
Air changes with temperature
Recommended combustion settings
based on inlet air temperature
(for locations
operating with outside air temperature between -20°F and
+90°F)