Ducane Furnace Model MPGA100B4A Manual

The Ducane MPGA100B4A is a high-efficiency gas furnace with 100,000 BTU input capacity, single-stage operation, multi-speed blower, and AFUE rating up to 80%. Features include hot surface ignition, induced draft combustion, safety controls, and compatibility with standard thermostats. Below are key sections for safety, features, installation, operation, maintenance, and troubleshooting.

1. Features at a Glance 2. Installation Requirements 3. First-Time Setup 4. Technical Specifications 5. Controls and Operation 6. Wiring and Connections 7. Maintenance Procedures 8. Safety Features 9. Care & Cleaning 10. Regulatory Information 11. Troubleshooting

Features at a Glance

Key components: Gas valve, burners, heat exchanger, blower assembly, induced draft motor, control board, pressure switches, and safety controls.

Feature	Description
Input Capacity	100,000 BTU/hour
AFUE Rating	Up to 80% efficiency
Gas Type	Natural gas (convertible to LP)
Ignition System	Hot surface ignition
Venting	PVC or ABS plastic pipe
Blower Type	Multi-speed PSC motor
Control System	Integrated furnace control board
Safety Features	Flame rollout, limit switches, pressure switches
Dimensions	Standard upflow configuration
Warranty	Limited lifetime heat exchanger

Installation Requirements

Professional installation required. Verify local codes and obtain permits.

Location: Install in dry, clean area with adequate combustion air and service clearance.
Venting: Use approved PVC or ABS pipe; maintain proper slope and termination clearances.
Gas Supply: Connect to properly sized gas line with sediment trap and shut-off valve.
Electrical: Connect to 120V AC power with proper grounding and disconnect.
Ductwork: Ensure proper sizing and sealing for efficient airflow.

WARNING! Gas appliances can produce carbon monoxide. Proper installation and venting are critical for safety.

First-Time Setup

Initial startup must be performed by qualified technician.

Verify all connections: Gas, electrical, venting, and ductwork.
Check gas pressure: Adjust manifold pressure per specifications.
Test safety controls: Verify operation of limit switches and pressure switches.
Set blower speeds: Adjust for proper airflow and temperature rise.
Program thermostat: Connect compatible 24V thermostat.

CAUTION! Never bypass safety controls. Test for gas leaks before operation.

Technical Specifications

Model: MPGA100B4A
Input BTU: 100,000
Output BTU: 80,000
AFUE: 80%
Gas Pressure: Natural gas 3.5" WC, LP gas 10" WC
Electrical: 120V/60Hz, 6.5 amps
Blower Speeds: Multi-speed for heating and continuous fan
Temperature Rise: 35-65°F
Venting Size: 2" or 3" PVC/ABS
Dimensions: 21"W x 21"D x 46"H

Controls and Operation

Integrated control board manages ignition sequence, blower operation, and safety monitoring.

Operation Sequence: Thermostat call for heat → Inducer motor starts → Pressure switch proves draft → Hot surface ignition → Gas valve opens → Flame sensed → Blower starts after delay.

Status Lights: Control board LED indicates normal operation or fault codes.

Thermostat: Compatible with standard 24V heating thermostats; programmable models recommended for efficiency.

Wiring and Connections

24V thermostat connections: R (power), W (heat), G (fan), C (common).

Disconnect power before servicing electrical components.
Verify proper grounding and wire sizing.
Use wire nuts for secure connections.
Route wiring away from hot surfaces and moving parts.

Tip: Label all wires before disconnecting for easy reassembly.

Maintenance Procedures

Annual maintenance by qualified technician recommended.

Filter replacement: Check monthly, replace as needed (typically 1-3 months).
Burner inspection: Clean burners and verify proper flame pattern.
Heat exchanger: Inspect for cracks or corrosion.
Blower cleaning: Remove dust and debris from blower wheel and housing.
Venting inspection: Check for obstructions and proper slope.
Safety controls: Test operation of all limit and pressure switches.

WARNING! Turn off gas and electrical power before performing maintenance.

Safety Features

Flame rollout switch: Detects burner flame outside combustion area. Limit switches: Prevent overheating. Pressure switches: Verify proper venting draft. Thermal fuse: Additional overheating protection.

Care & Cleaning

Keep area around furnace clean and free of combustible materials. Clean exterior with damp cloth only.

CAUTION! Do not use water or cleaning solutions on electrical components. Keep filters clean for proper airflow.

Regulatory Information

ANSI Z21.47/CSA 2.3: Certified for US and Canada. UL listed. Must be installed in accordance with National Fuel Gas Code and local codes. For support, contact Ducane HVAC at 1-800-338-0525 or visit www.ducanehvac.com.

Troubleshooting

Symptom	Possible Cause	Corrective Action
Furnace won't start	Power, thermostat, door switch	Check circuit breaker, thermostat setting, door switch engagement
No heat	Gas supply, ignition	Verify gas valve on, check for ignition attempts, inspect flame sensor
Short cycling	Dirty filter, airflow	Replace filter, check for blocked vents, verify proper temperature rise
Blower won't run	Motor, capacitor, control	Check for power to blower, test capacitor, verify control board output
Lockout mode	Safety switch, flame	Reset power, check fault code, inspect safety controls and flame sensor

Reset: Turn power off for 30 seconds then restore.

Service: 1-800-338-0525; www.ducanehvac.com