York AHU Operation And Maintenance page 35

FORM 102.20-OM2
ISSUE DATE: 6/01/2015
Both burners utilize a combustion air blower, and use
an exhaust blower, called an induced draft (ID) blower,
which keeps the combustion chamber at a slight nega-
tive pressure. Verification of this negative pressure and
other system parameters is part of a proper start up pro-
cedure.
Preliminary Coordination
Contact the contractor/customer who requested start-
up, and do the following:
• Ensure the AHU and system is capable of design
airflow for gas heat start-up.
• Ensure reliable power is available.
• Verify the following:
• Verify the AHU was properly started up.
• Gas lines are purged of air to the equipment
valve.
• Controls are complete.
• Flue (stack) is correctly installed, if parts
were shipped loose.
Recommended Tools
• Electrical Multimeter with Amprobe.
• Heating AHU Installation and Operation Instruc-
tions, which are provided with every heating AHU
for technical information and troubleshooting.
• Magnehelic Gauge 0-25 in WC, Dwyer Series
2000 or Model 1227 Dual Range Manometer for
checking pressure over fire (draft).
• Control Signal Generator, 0 to 20 mA (Altek-234
or 334A) - For 2 to 10 VDC signal add 500 ohms
in series with signal generator.
JOHNSON CONTROLS
SECTION 2 - START-UP AND OPERATION
• Magnehelic Gauge 0-15 in WC and 0 to 3 lb (Dw-
yer series-2000) or Monometer (Dwyer- 1227)
Duel Range Monometer for checking supply gas
pressure and manifold gas or pilot gas pressure.
• Honeywell - S7800A Test Module for use on
(Honeywell-7800) Series Relay Module, which is
available through Airside Parts
• Flue Gas Analyzer (CO
• Stack Thermometer (0°F-1000°F approx.)
• Digital Manometer (replaces Magnehelic Gauge):
Digital Manometer, Cat. #475-1 FM-AVSeries:
475-1 Mark III, Range: 0 to 19.99 In. W.C.from
Dwyer Instruments, Inc.
Pre-Start-Up Checklist
Condensate trap must be installed prior
to start-up by the installing contractor.
Refer to Figure 28 on page 36 for installing the gas
furnace condensate drain trap.
Use the following information to check the AHU be-
fore starting it:
• Verify the AHU was properly started up, and that
airflow is at the design maximum for the heating
cycle. Refer to the air balance report.
• Set the bypass damper, if provided.
• Airflow proving switch for main supply fan in-
stalled and operational.
• Check with the control technician: two-minute
post-purge programmed in AHU controller. Upon
call for unit stop, burner cycles off, then AHU fan
cycles off two minutes later.
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