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APPENDIX E
QUICK REFERENCE INFORMATION
355MAV & 355AAV PRESSURE SWITCH MAKE/BREAK POINTS
HIGH-HEAT PRESSURE SWITCH
LOW-HEAT PRESSURE SWITCH
UNIT SIZE (BTUH)
Make Point
Break Point
Make Point
Break Point
40,000
1.81 in.wc max
1.63 in. wc +/- 0.05
0.75 in. wc max
0.60 in. wc +/- 0.05
60,000
80,000
100,000
120,000
1.81 in.wc max
1.63 in. wc +/- 0.05
0.95 in. wc max
0.80 in. wc +/- 0.05
355BAV PRESSURE SWITCH MAKE/BREAK POINTS
HIGH-HEAT PRESSURE SWITCH
LOW-HEAT PRESSURE SWITCH
UNIT SIZE (BTUH)
Make Point
Break Point
Make Point
Break Point
60,000
0.86 in. wc max
0.71 in. wc +/- 0.05
80,000
0.91 in. wc max
0.76 in. wc +/- 0.05
100,000
0.95 in. wc max
0.81 in. wc +/- 0.05
120,000
1.81 in.wc max
1.63 in. wc +/- 0.05
0.86 in. wc max
0.71 in. wc +/- 0.05
Flame Sensor Microamperage:
Microamp Range: 0.5 to 6.0 microamps
Typical Reading:
4 to 6 microamps in high heat
Hot Surface Ignitor Reading:
355MAV
– Ohm reading of new HSI @ 70°F: 40 to 90 ohms (resistance will go up with HSI life and exceed the new HSI resistance over time).
355AAV & 355BAV
– Ohm reading of HSI @ 70°F:
40 to 70 ohms
(resistance will remain relatively stable over the life of the igniter).
The Silicon Nitride igniter in this furnace is not voltage sensitive and will work within the voltage range of 102 to 132 VAC. Hence, there is no voltage
regulation circuits on the furnace control board. A new Silicon Nitride igniter has a normal resistance range of 40 to 70 ohms at room temperature and
is relatively stable over the life of the igniter. The igniter resistance will increase with temperatures above room temperature.
Gas Valve Ohm Readings:
M to C: Resistance cannot be measured with an ohm meter because there is a bridge rectifier in the gas valve circuit.
Hi to C: Resistance cannot be measured with an ohm meter because there is a bridge rectifier in the gas valve circuit.
Power Choke (Inductor):
Run unit in cooling mode, measure motor amp draw before power choke. Then rerun unit in cooling mode, but this time measure amp draw without
power choke in line. The amp draw should be higher without power choke. Some ammeters will register a lower amp draw (look for a change in
amperage).
