Trane Horizon OADG Series Installation, Operation And Maintenance Manual page 54

Startup
3. Confirm Gas Flow at Unit
WARNING
Hazardous Voltage and Gas!
Failure to turn off gas or disconnect power before
servicing could result in an explosion or electrocution
which could result in death or serious injury. Turn off
the gas supply and disconnect all electric power,
including remote disconnects, before servicing the unit.
Follow proper lockout/tagout procedures to ensure the
power can not be inadvertently energized.
AVERTISSEMENT
Tension dangereuse et présence de gaz!
Le non-respect de l'obligation de couper le gaz ou
l'alimentation électrique avant de procéder à une
opération d'entretien peut entraîner une explosion ou
une électrocution pouvant résulter en des blessures
graves, voire mortelles. Avant toute intervention sur
l'unité, couper l'approvisionnement en gaz et
l'ensemble de l'alimentation électrique, y compris les
disjoncteurs à distance. Suivez scrupuleusement les
procédures de verrouillage/mise hors service
préconisées pour empêcher tout rétablissement
accidentel de l'alimentation électrique.
Open door to unit vestibule housing the gas heater.
Move gas control lever to "OFF" position. Remove 
1/8-in. pressure taps (see
modulating and on-off sections of the split heater
manifold. Install a barbed fitting in both 1/8-in. tapped
holes for connection to individual gas manometers.
Note: There is a third 1/8-in. gas pressure tap located in
the pipe connecting the main valve/regulator and
modulating valve. Maximum pressure into
modulating valve is 5-in. The On-Off gas valve
includes a regulator adjustment device that is
located on the top of the valve. Use this device to
regulate valve output to modulating valve as
required.
Wait 5 minutes for any gas to clear. If you smell gas, see
Step 2 and correct leak. If you don't smell gas or have
corrected any leaks, go to
4. Burner Starting Sequence and Burner Ignition
Figure 42, p. 56 illustrates indirect fired gas furnace
components.
5. Main Gas Supply
Turn manual gas cock "ON".
6. Split Manifold High Fire and Burner Test
Open all manual gas valves. Turn power on at unit's
main disconnect switch. Open gas supply manual shut-
off valve. Using unit display (or computer with Trane
Tracer TU), proceed to System Status Display and
Override all Compressor stages OFF, Disable
Dehumidification, Disable Economizer Mode, Disable
54
Figure 42, p. 56) from both
Step 4.
ERV. If two heaters are installed, test heating with split
manifold first by overriding burner 2 OFF. Override
heating Output Command to 100.0 percent if one
heater is installed and to 49 percent if two heaters are
installed. Override Heat Cool Mode Active to Heat. This
will enable call for heat to split manifold heater.
Depending on outdoor air temperature, at time of
startup, heater high limit temperature may be
exceeded causing limit switch to trip. Limit switch is
auto-reset. Limit switch must be jumpered out of the
circuit if OA temperature dictates.
With limit switch closed, the draft inducer will run on
high speed for 10 seconds for proof of high and low
airflow switch closure, then begin a 30-second pre-
purge period. At the end of the pre-purge the direct
spark will be energized and On-Off gas valve will open
for a 5-second ignition trial. Following successful
ignition, the inducer remains on high for 10-second
flame stabilization, followed by 30-second warm up.
Should the flame go out or the burner fail to light, an
ignition retry will initiate following a 15-second inter-
purge period.
Following successful ignition, manifold pressure
should be 1.2 in. WC during the warm-up period. The
manifold pressure will rise to 3.5 in. WC at 100 percent
firing rate. Following these sequences to check low fire
gas pressure for modulating section, reduce Heating
Output Command to 0 percent. Inducer speed will
reduce to low speed. Correct gas pressure for
modulating manifold section of heater at 0 percent
output signal or low fire will be 0.4 in. WC. For
modulating sections, the outlet gas pressure from
main/regulator valve into the modulating valve is
5-in. WC.
Main On-Off valves in 1/2-in. gas line require 3/32-in.
Allen wrench to adjust outlet gas pressure. Valves in 
3/4-in. gas line require flat blade screwdriver to adjust
outlet gas pressure. Following these sequences,
inducer speed will reduce to low speed and will now be
speed-controlled by the heater controller based on gas
input to burners.
With heating command at 100 percent and with a
single split manifold heater installed, the On-Off
section of the heater will require the modulating
section to prove ON before the On-Off section will
enable. Inducer speed high at all times the On-Off
section is in ignition sequence or firing. On-Off section
sequence includes a 1-second ignition pre-purge
followed by 4-second ignition trial. Ignition or flame
failure will be followed by 30-second inter-purge for
two ignition retry then 5-minute lockout period if both
retry attempts fail. Correct manifold gas pressure for
On-Off heater section is 3.5 in. WC.
For units including an additional separate On-Off
heater, set heat command output to 49 percent to run
modulating heater startup. When complete with
modulating heater startup, increase heat output
command to 100 percent to start up the second heater.
OAU-SVX006E-EN