Direct Gas Make-Up Air Quick Start Guide - 120 Baso Terminal Strip
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 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
1. Energize the supply fan by connecting terminals R to G.
2. Verify blower rotation is correct.
- To reverse the rotation on three phase units, disconnect and lock out the power, then interchange any two power leads going to the motor.
- Check motor amp draw and compare to motor nameplate FLA – reduce airflow if amp draw is greater than FLA.
3. Check burner pressure differential. (Fig. 1)
a. Connect manometer to outer sensing probes (Fig. 1)
b. See Fig 2 for acceptable pressure differential for each gas type and unit configuration.
c. Adjustment (if needed) - Test and balance should be completed prior to unit start-up. If T&B has not been completed, baffle or fan speed should be adjusted to achieve desired pressure differential. To increase pressure differential, decrease the burner baffle opening evenly or increase airflow. To decrease differential, increase the burner baffle opening evenly or decrease fan speed. If pressure differential can't be achieved through baffle adjustment or sheave adjustment, reference IOM for further setup instructions.
Fig. 1 Measuring the Pressure Drop
A digital manometer is connected via tubing to pressure taps on a piece of equipment. The manometer displays a reading of 0.69. This setup is used for measuring pressure drop.
Fig. 2 Pressure Differential
| NG | LP | |
|---|---|---|
| Constant Volume | .6 - .7 | .8 - .9 |
| Variable Volume | .5 - .8 | .7 - 1.0 |
| Recirculation | .5 - .8 | .7 - 1.0 |
(Values shown as in. wg)
4. 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.
5. Verify inlet air sensor (TS4) setting is set above outside air temp (if equipped).
6. Energize the heating by connecting terminals R to W1.
7. Check pilot flame signal.
- Close main hand valve.
- LP only: Connect manometer to pilot tee test port. Energize fan; zero manometer; energize heat. Pilot pressure: NG/LP 1.5" to 3" wg
- Measure flame current with pilot valve lit and without main gas flowing.
- Set meter to μA DC scale.
- Locate flame signal terminals on BASO ignition control, place red lead on [+] terminal and black lead on [-] terminal. (Fig. 3)
- Recommended minimum flame sense current range, 0.1 to 1.0 µA DC.
Fig. 3 BASO Ignition Control
A close-up view of a BASO ignition control unit. It shows various terminals and wiring connections. Labels indicate 'Pressure Switch' and 'Pressure Taps'.
8. Open main hand valve and then set maximum firing rate to the design temperature rise located on the direct gas nameplate. (Fig. 2)
a. 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).
b. While measuring temp rise, adjust combo valve regulator to achieve desired temperature rise. (Temp rise = discharge temp - inlet temp)
Fig. 4 Separate Regulator & Modulating Valves
An illustration showing separate components for gas regulation. One component is labeled 'Separate Regulator & Modulating Valves'. Arrows point to adjustment screws labeled 'Remove cap to access maximum firing rate adjustment' and 'Minimum firing rate adjustment'.
Fig. 5 Combined Modulating Regulator
An illustration of a combined modulating regulator unit. Arrows point to adjustment screws labeled 'Minimum firing rate adjustment' and 'Maximum firing rate adjustment'.
9. Set the minimum firing rate to achieve a small ribbon of continuous blue flame across the burner. (Fig. 2)
- Disconnect one of the wires going to the modulating valve and isolate.
- Set the minimum firing rate by adjusting the minimum firing rate adjustment on the modulating valve.
- Cycle the heat to make sure the burner can light at this low fire setting.
10. Remove power to terminal W1 to remove the call for heat.
Reconnect wires to Maxitrol amplifier and modulating valve.
