Table of Contents
Advertisement
HEATING
NUMBER
INPUT
OF
(BTUH)*
ORIFICES
40,000
2
60,000
2
90,000
3
115,000
3
130,000
3
*When a unit is converted to propane, different size orifices must be used. See separate natural-to-propane conversion kit instructions.
†Based on altitudes from sea level to 2000 ft. above sea level. For altitudes above 2000 ft., reduce input rating 4% for each 1000 ft. above sea level. In Canada, from
2000 ft. above sea level to 4500 ft. above sea level, derate the unit 10%.
START UP HEATING SECTION AND MAKE ADJUSTMENTS
IMPORTANT: Complete the required procedures given in the
Pre-Start-Up section above before starting the unit.
Do not jumper any safety devices when operating the unit.
Make sure that burner orifices are properly aligned. Unstable
operation may occur when the burner orifices in the manifold are
misaligned.
NOTE: Make sure that gas supply has been purged, and that all
gas piping has been checked for leaks.
CHECK HEATING CONTROL — Start and check the unit for
proper heating control operation as follows. (see furnace lighting
instructions located inside burner or blower access panel.):
1. Place room thermostat SYSTEM switch in the HEAT position
and the FAN switch in the AUTO position.
2. Set the heating temperature control of the thermostat above
room temperature.
3. The induced-draft motor will start.
4. After a call for heating, the main burner should light within 5
seconds. If the burners do not light, there is a 22-second delay
before another 5-second try. If the burners still do not light,
this sequence is repeated. If the burners do not light within 15
minutes from the initial call for heat, there is a lockout. To
reset the control, break the 24-v power to W.
5. The evaporator fan will turn on 45 seconds after the flame has
been established. The evaporator fan will turn off 45 seconds
after the thermostat has been satisfied.
CHECK GAS INPUT—Check gas input and manifold pressure
after unit start-up (See Table 6.) If adjustment is required, proceed
as follows:
The rated gas inputs shown in Table 6 are for altitudes from sea
level to 2000 ft. above sea level. These inputs are based on natural
gas with a heating value of 1050 Btu/ft
propane gas with a heating value of 2500 Btu/ft
gravity. For elevations above 2000 ft., reduce input 4% for each
1000 ft. above sea level. When the gas supply being used has a
different heating value, or specific gravity, refer to national and
local codes, or contact your distributor to determine the required
orifice size.
These units are designed to consume the rated gas inputs
using the fixed orifices at specified manifold pressures as
shown in Table 6. DO NOT REDRILL THE ORIFICES
UNDER ANY CIRCUMSTANCES.
Table 6—Heating Inputs
GAS SUPPLY PRESSURE
(IN. WG)
Natural
Min
Max
4.0
13.0
4.0
13.0
4.0
13.0
4.0
13.0
4.0
13.0
3
at 0.65 specific gravity, or
3
at 1.5 specific
Propane†
Min
Max
7.0
13.0
7.0
13.0
7.0
13.0
7.0
13.0
7.0
13.0
ADJUST GAS INPUT—The gas input to the unit is determined by
measuring the gas flow at the meter or by measuring the manifold
pressure. Measuring the gas flow at the meter is recommended for
natural gas units. The manifold pressure must be measured to
determine the input of propane gas units.
MEASURE GAS FLOW (Natural Gas Units)—Minor adjustment
to the gas flow can be made by changing the manifold pressure.
The manifold pressure must be maintained between 3.4 and 3.6 in.
wg. If larger adjustments are required, change main burner orifices
following the recommendations of national local codes.
NOTE: All other appliances that use the same meter must be
turned off when gas flow is measured at the meter.
Proceed as follows:
Turn off gas supply to unit.
1. Remove pipe plug on manifold (see Fig. 18) then connect
manometer at this point. turn on gas to unit.
2. Record number of seconds for gas meter test dial to make one
revolution.
3. Divide number of seconds in Step 3 into 3600 (number of
seconds on one hour).
4. Multiply result of Step 4 by the number of cu. ft. shown for
one revolution of test dial to obtain cu. ft. of gas flow per hour.
5. Multiply result of Step 5 by Btu heating value of gas to obtain
total measured input in Btuh. Compare this value with heating
input shown in Table 6. (Consult the local gas supplier if the
heating value of gas is not known.)
EXAMPLE: Assume that the size of test dial is 1 cu. ft., one
revolution takes 32 seconds, and the heating value of the gas is
3
1050 Btu/ft
. Proceed as follows:
1. 32 seconds to complete one revolution.
2. 3600 ÷ 32 = 112.5
3. 112.5 x 1 = 112.5 ft
4. 112.5 x 1050 = 118,125 Btuh input.
If the desired gas input is 115,000 Btuh, only a minor change in the
manifold pressure is required.
Observe manifold pressure and proceed as follows to adjust gas
input:
1. Remove cover screw over regulator adjustment screw on gas
valve.
2. Turn regulator adjustment screw clockwise to increase gas
input, or turn regulator adjustment screw counterclockwise to
decrease input. Manifold pressure must be between 3.4 and
3.6 in. wg.
14
MANIFOLD PRESSURE
(IN. WG)
Natural
Propane†
3.5
3.5
3.5
3.5
3.5
3.5
3.5
3.5
3.5
3.5
3
of gas flow/hr.
Advertisement
Table of Contents
