York XT AHU - STARTING THE GAS BURNER; GAS BURNER START-UP CHECKS AND ADJUSTMENTS

JOHNSON CONTROLS
37
SECTION 2 - START-UP AND OPERATION
FORM 102.20-OM2
ISSUE DATE: 6/01/2015
2
14. Connect a manometer or other suitable device to
the heat exchanger draft port located on the side
of the AHU near the burner. The expected draft
should read slightly negative about -0.03 inches
WC. The draft port is typically made of 3/4 in
steel pipe and may be plugged. Remove plug and
add a small stop valve and a nipple for a rubber
tube.
15. Install the Honeywell S7800 Test Module, if
available.
16. Connect the signal generator (0-20mA) to ter-
minals in place of modulation control signal (for
2-10VDCsignaladda500Ωresistorinseries).
17. Visually check that the ue (stack) is secure
and connected properly. Typical connections are
shown at the end of these instructions.
18. The burner panel's on/off switch should be off.
19. The system is now ready for start up.
FIGURE 29 - OPEN FUSE DISCONNECTS
LD12903
BURNER
CONTROL
PANEL
FIGURE 30 - SET ID FAN DAMPER
LD12910
FIGURE 31 - CHECK MAIN GAS SUPPLY
PRESSURE
LD12905
Starting the Burner
1. Prior to starting the burner, the technician must
verify the incoming gas pressure. A minimum
pressure is listed on the burner test report. The
maximum pressure is listed as well.
2. Open the manual gas valves on gas supply and
pilot line.
3. Initiate a call for heat or use jumper to create a
call for heat.
4. Turn the burner panel on/off switch to on.
5. Once there is a call for heat, a 30-second pre-
purge period is initiated to remove any gases from
the heat exchanger. The burner will go through a
second purge before ignition.
6. The burner will automatically go to low re at
start-up.After proof of low re, the burner will
modulateuptohighre,whichmaytake15sec-
onds for a Powerame burner, and 90-180 sec-
onds for the Eclipse burner. After the burner oper-
ates at High Fire use the manometer connected to
the Heat Exchanger Draft Port as shown in Figure
32 on page 38, observe the reading. A pressure
of-0.03inchesWCisexpectedfordraftoverre.
Readings may differ slightly from those shown on
the Burner Test Report.
7. For valid readings before making any adjust-
ments,allowtheburnertoreatleast20minutes
to allow the heat exchanger to rise to the operating
temperature.
8. Observe the gas manifold pressure and compare
to the data on the Burner Test Report under both
highandlowreconditions.