ACCUREX Direct Gas Make-Up Air User Guide

: June 3, 2024
: ACCUREX

Table of Contents

ACCUREX Direct Gas Make-Up Air
Pre-Start Information
INSTRUCTION
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Documents / Resources
- Read User Manual Online (PDF format)
- Download This Manual (PDF format)

ACCUREX Direct Gas Make-Up Air

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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.

Pre-Start Information

To energize the unit control circuits (field-wiring shown on the diagram with dashed lines):

a. Exhaust fan (optional) – Connect terminals R to H
b. Supply fan – Connect terminals R to G
c. Heating – Connect terminals R to W1
d. Cooling (optional) – Connect terminals R to Y1

INSTRUCTION

Energize the supply fan by connecting terminals R to G.
Verify blower rotation is correct.
- a. To reverse the rotation on three-phase units, disconnect and lock out the power, then interchange any two power leads going to the motor.
- b. Check motor amp draw and compare to motor nameplate FLA – reduce airflow if amp draw is greater than FLA.
Check burner pressure differential. (Fig. 1)

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  * a. Connect manometer to outer sensing probes
  * b. Should be between 0.6-0.7 in wg for natural gas and 0.8-0.9 for LP.
  * c. To increase the differential pressure, decrease the burner baffle opening evenly or increase airflow.
  * d. To decrease the differential pressure, increase the burner baffle opening evenly or decrease airflow.

Verify the unit inlet gas pressure:
- a. 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.
Verify inlet air sensor (TS4) setting is set above the outside air temp (if equipped). If unit has a microprocessor, verify the heating lockout setting.
Energize the heating by connecting terminals R to W1. If the unit has a microprocessor, enable heat by setting heat control to 1%.
Check the pilot flame signal.
- a. Close the main hand valve.
- b. LP only: Connect the manometer to the pilot test port. Energize fan; zero manometers; energize heat; adjust pilot pressure to 0.5 in. wg. Natural gas pilot pressure is preset at the factory. (If not using a digital manometer, see IOM for further details on the pilot differential for LP).
- c. Measure flame current with the pilot valve lit and without the main gas flow.
- d. Set meter to μA DC scale.
- e. Locate flame signal terminals on BASO ignition control, place red lead on [+] terminal and black lead on [-] terminal. (Fig. 4). Recommended minimum pilot-only flame sense current of 1 μA DC.
Open the main hand valve and then set the maximum firing rate to the design temperature rise located on the direct gas nameplate. (Fig. 3)
- a. Send the unit to the high fire by removing the wire connected to terminal 3 of the Maxitrol 14/44 amplifier. (If equipped with the SC25 Amplifier, connect terminals T1 and T2).
- b. While measuring temp rise, adjust the combo valve regulator to achieve desired temperature rise. (Temp rise = discharge temp – inlet temp)
Set the minimum firing rate to achieve a small ribbon of continuous blue flame across the burner. (Fig. 2)
- a. Disconnect one of the wires going to the modulating valve and isolate.
- b. Set the minimum firing rate by adjusting the minimum firing rate adjustment on the modulating valve.
- d. Cycle the heat to make sure the burner can light at this low fire setting.
Remove power to terminal W1 to remove the call for heat. Reconnect wires to the Maxitrol amplifier and modulating valve.