GREENHECK 914005 Direct Gas Make Up Air User Guide
- June 5, 2024
- GREENHECK
Table of Contents
GREENHECK 914005 Direct Gas Make Up Air User Guide
Direct Gas Make-Up Air Quick Start Guide – Pilot Ignition ≤ 1200 mbh
This quick start document is intended to help with getting the initial unit
startup completed, but does not replace the IOM. Please read the IOM for all
safety information and precautions before performing any work on the
equipment.
Complete pre-start checks and blower start-up prior to this procedure.
Installation, Operation and Maintenance Manual
Direct Gas-Fired Start-Up Video
Pre-Start Information
To energize the unit control circuits
(field-wiring shown on diagram with dashed lines):
- Exhaust fan (optional) – Connect terminals R to H
- Supply fan – Connect terminals R to G
- Heating – Connect terminals R to W1
- Cooling (optional) – Connect terminals R to Y1
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Energize the supply fan by connecting terminals R to G.
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Verify blower rotation is correct.
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To reverse the rotation on three phase units, disconnect and lock out the power, then interchange any two power leads going to the motor.
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Check motor amp draw and compare to motor nameplate FLA – reduce airflow if amp draw is greater than FLA.
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Check burner pressure differential. (Fig. 1)
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Connect manometer to outer sensing probes
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Should be between 0.6-0.7 in wg for natural gas and 0.8-0.9 for LP.
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To increase the differential pressure, decrease the burner baffle opening evenly or increase airflow.
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To decrease the differential pressure, increase the burner baffle opening evenly or decrease airflow.
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Verify the unit inlet gas pressure:
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Inlet gas pressure needs to be equal to or greater than the “minimum for maximum output”, but not to exceed the “maximum gas pressure” listed on the unit gas pressure label.
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Verify inlet air sensor (TS4) setting is set above outside air temp (if equipped). If unit has microprocessor, verify heating lockout setting.
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Energize the heating by connecting terminals R to W1. If unit has microprocessor, enable heat by setting heat control to 1%.
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Check pilot flame signal.
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Close main hand valve.
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LP only: Connect manometer to pilot test port. Energize fan; zero manometer; energize heat; adjust pilot pressure to 0.5 in. wg. Natural gas pilot pressure is preset at factory. (If not using digital manometer, see IOM for further details on pilot differential for LP).
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Measure flame current with pilot valve lit and without main gas flowing.
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Set meter to μA DC scale.
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Locate flame signal terminals on BASO ignition control, place red lead on [+] terminal and black lead on [-] terminal. (Fig. 4)
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Recommended minimum pilot only flame sense current of 1 μA DC.
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Open main hand valve and then set maximum firing rate to the design temperature rise located on the direct gas nameplate. (Fig. 3)
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Send unit to high fire by removing wire connected to terminal 3 of Maxitrol 14/44 amplifier. (If equipped with the SC25 Amplifier, connect terminals T1 and T2).
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While measuring temp rise, adjust combo valve regulator to achieve desired temperature rise. (Temp rise = discharge temp – inlet temp)
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Set the minimum firing rate to achieve a small ribbon of continuous blue flame across the burner. (Fig. 2)
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Disconnect one of the wires going to the modulating valve and isolate.
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Set the minimum firing rate by adjusting the minimum firing rate adjustment on the modulating valve.
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Cycle the heat to make sure the burner can light at this low fire setting.
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Remove power to terminal W1 to remove the call for heat. Reconnect wires to Maxitrol amplifier and modulating valve.
