101
3
JOHNSON CONTROLS
5276178-JIM-C-0118
Make sure that burners are level and seat at the rear of
the gas orifice.
Adjustment of Temperature Rise
The temperature rise (or temperature difference between
the return air and the heated air from the furnace) must
lie within the range shown on the CGA/ETL rating plate
and the data in Table 3.
After the temperature rise has been determined, the CFM
can be calculated as follows:
BTUH × 0.8
1.08 × F Degrees Temp Rise
CFM =
After about 20 minutes of operation, determine the
furnace temperature rise. Take readings of both the
return air and the heated air in the ducts (about six feet
from the furnace) where they will not be affected by
radiant heat. Increase the blower CFM to “
decrease”
the temperature rise; “decrease” the blower CFM to
“
increase”
the rise.
Refer to Table 18 for supply air
blower motor and drive data.
Minimum allowable CFM
is 6,000. Limit will open below this rating.
Checking Gas Input
Natural Gas
1. Turn OFF all other gas appliances connected to the
gas meter.
2. With the furnace turned on, measure the time
needed for one revolution of the hand on the small-
est dial on the meter. A typical gas meter usually
has a 1/2 or a 1 cubic foot test dial.
3. Using the number of seconds for each revolution
and the size of the test dial increment, find the cubic
feet of gas consumed per hour from Table 38.
If the actual input is not within 5% of the furnace rating
(with allowance being made for the permissible range
of the regulator setting), replace the orifice spuds with
spuds of the proper size.
To find the BTU input, multiply the
number of cubic feet of gas consumed
per hour by the BTU content of the
gas in your particular locality (contact
your gas company for this information
- it varies widely from city to city).
TABLE 51 - GAS RATE - CUBIC FEET PER
HOUR
SECONDS FOR
ONE REV.
SIZE OF TEST DIAL
1/2 CU. FT
1 CU. FT.
2
900
1800
4
450
900
6
300
600
8
225
450
10
180
360
FIGURE 33 - TYPICAL FLAME APPEARANCE
Example: By actual measurement, it takes 7 seconds for
the hand on the one cubic foot dial to make a revolution
with just a 570,000 BTUH furnace running. Read across
to the column in Table 38, headed 1 Cubic Foot where
you will determine that 525 cubic feet of gas per hour
are consumed by the furnace at that rate. Multiply 525
x 1050 (the BTU rating of the gas obtained from the
local gas company). The result of 551,000 BTUH is
within 5% of the 570,000 BTUH rating of the furnace.
ELECTRIC HEATING
The electric furnace is operational as shipped from the
factory and does not receive any field adjustments.
REFRIGERATION SYSTEM
CHARGE:
Each system is fully factory charged
with R-410A. The correct charge appears on the unit
nameplate.
Thermal Expansion Valves: The Series 40 units have
4 independent refrigeration systems. These TXVs are
set to maintain 15°F superheat leaving the evaporator
coil. The superheat on each valve is adjustable,
however, adjustments should only be made if absolutely
necessary.
Refer to previous section to adjust subcooling
and superheat.
FILTER DRIER:
Each system is equipped with a filter
drier. The drier should be replaced whenever moisture
is indicated in the system.
LD14112
Содержание 40 25 TON
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