
50
AIR FLOW
The importance of proper air flow over
the heat exchanger cannot be over
emphasized.
IT IS IMPORTANT THAT EACH DUCT
SYSTEM BE SIZED AND INSTALLED
FOR THE SPECIFIC APPLICATION
BY PROPERLY APPLYING THE
APPROPRIATE INDUSTRY
ACCEPTED STANDARD. IF LESS
THAN MINIMUM STANDARDS ARE
APPLIED, THE EQUIPMENT USER
COULD EXPECT TO EXPERIENCE
HIGHER UTILITY BILLS, MAJOR
COMPONENT FAILURE, VARYING
DEGREES OF AIR NOISE OR OTHER
UNSATISFACTORY ISSUES, OVER
WHICH THE MANUFACTURER HAS
NO CONTROL.
TEMPERATURE RISE CHECK
To determine if the air flow is correct,
make a temperature rise check.
1. Insert a thermometer in the supply
air duct as close to the furnace as
possible yet out of a direct line from
the heat exchanger. See Figure 49.
2. Insert a thermometer in the return
air duct as close to the furnace as
possible.
3. Operate the furnace.
4. When the thermometer in the
supply air duct stops rising
(approximately five minutes),
subtract the return air temperature
from the supply air temperature.
The difference is the temperature
rise.
5. Compare the measured
temperature rise to the approved
temperature rise range listed on the
furnace name plate. See Figure 50.
If the measured temperature rise is
above the approved range, the air flow
is too low. More air must be moved by
speeding up the blower, by removing
restrictions in the duct system, or by
adding more supply or return air duct. If
the measured temperature rise is below
the approved range, the air flow is too
much. Use lower speed tap on the multi-
speed blower.
THE MEASURED TEMPERATURE
RISE SHOULD BE AS CLOSE TO THE
MIDDLE OF THE STATED RANGE AS
POSSIBLE. FOR EXAMPLE, IF THE
RISE RANGE IS 40 TO 70 DEGREES,
FIGURE 49
TEMPERATURE RISE MEASUREMENT
FIGURE 50
TYPICAL FURNACE NAME PLATE
!
WARNING
!
CAUTION
THE MOST IDEAL RISE WOULD BE
55 DEGREES (THE MIDDLE OF
THE RISE RANGE). IN ALL
APPLICATIONS, THE INSTALLER
MUST ADJUST THE
TEMPERATURE RISE TO THIS
"MIDDLE" POINT AS CLOSELY AS
POSSIBLE. ALSO, THE
TEMPERATURE RISE SHOULD
NEVER BE ABOVE OR FALL
BELOW THE STATED RANGE.
DOING SO COULD CAUSE
DAMAGE TO THE HEAT
EXCHANGER OR INTERMITTENT
OPERATION WHICH COULD
CAUSE INJURY OR DEATH AND
WILL VOID THE
MANUFACTURER'S WARRANTY
FOR THIS PRODUCT.
AIR CONDITIONING DIVISION
FORT SMITH, ARKANSAS
Содержание 90RJ Series
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