MTI Furnace Manual

The MTI Furnace is a high-efficiency heating system designed for residential and light commercial use. This furnace features advanced combustion technology, multiple heat exchanger stages, variable-speed blower motor, digital thermostat compatibility, safety shut-off systems, and energy-saving modes. Operating on natural gas or propane, with input capacities ranging from 40,000 to 120,000 BTU/hr. Below are key sections for safety, features, installation, setup, operation, maintenance, and troubleshooting.

Features at a Glance

Key components: Stainless steel heat exchanger, variable-speed blower motor, electronic ignition system, pressure switches, flame sensor, gas valve, control board, air filter compartment.

Feature	Description
Heat Exchanger	Stainless steel construction for durability and efficiency
Blower Motor	Variable-speed ECM motor for quiet operation
Ignition System	Hot surface ignition for reliable startup
Pressure Switches	Safety monitoring of combustion air flow
Flame Sensor	Monitors burner flame presence
Gas Valve	Precision gas flow regulation
Control Board	Microprocessor-based system control
Filter Compartment	Standard 1-inch or 4-inch media filter compatible
Status Lights	LED indicators for diagnostic codes
Service Ports	Pressure test ports for service technicians

Installation

Unpack and inspect all components. Ensure proper clearances and ventilation.

1. Location selection: Choose well-ventilated area with proper clearances (minimum 1 inch sides, 6 inches front).
2. Gas connection: Use approved gas pipe; apply pipe thread sealant; pressure test for leaks.
3. Vent system: Install according to local codes; use approved vent materials.
4. Electrical: Connect to 120V AC power; install proper disconnect switch.
5. Thermostat wiring: Connect compatible thermostat using low-voltage wiring.

WARNING! Gas appliances can be dangerous; installation must be performed by qualified technician. Ensure proper ventilation to prevent carbon monoxide buildup.

First-Time Setup

Power on furnace; follow startup sequence.

1. System check: Verify all connections are secure and gas valve is open.
2. Thermostat setup: Program desired temperature settings and schedules.
3. Test operation: Set thermostat to heat mode; verify proper ignition and heating.
4. Airflow adjustment: Set blower speeds for optimal comfort and efficiency.
5. Safety checks: Verify proper venting and combustion air supply.

CAUTION! Never bypass safety devices. If furnace fails to start properly, shut off power and gas, then contact qualified service technician.

Specifications

• Heating Capacity: 40,000 - 120,000 BTU/hr
• Efficiency: 80% - 96% AFUE
• Fuel Type: Natural Gas or Propane
• Electrical: 120V AC, 60Hz
• Blower Motor: Variable-speed ECM
• Heat Exchanger: Stainless steel primary and secondary
• Vent Size: 2-inch to 4-inch PVC/CPVC
• Filter Size: 16x25x1 inch or 16x25x4 inch media
• Dimensions: Varies by model (typically 21"W x 21"D x 40"H)
• Warranty: 10-year heat exchanger, 5-year parts

Controls and Settings

Access control board via front panel. Status lights indicate system operation and error codes.

Thermostat Controls: HEAT/COOL/OFF mode, FAN AUTO/ON, temperature setting, program schedules.

System Settings: Blower speed adjustments, temperature limits, cycle rates, filter reminder reset. Diagnostic: LED status lights flash error codes (1 flash = pressure switch, 2 flashes = ignition failure, etc.). Safety: High limit switch, rollout switches, pressure switches, flame sensor.

Connecting Thermostat

Compatible with most 24VAC thermostats. Standard wiring: R (power), W (heat), G (fan), Y (cool), C (common).

1. Turn off furnace power at disconnect switch.
2. Remove thermostat cover and connect wires to appropriate terminals.
3. Match wire colors to terminal labels (R=red, W=white, G=green, Y=yellow, C=blue).
4. Secure wiring and replace cover.
5. Restore power and test operation.

Tip: For programmable thermostats, follow manufacturer's programming instructions for optimal energy savings.

Operating Modes

Supports heating, fan-only, and with AC unit, cooling operation.

1. Heating mode: Set thermostat to HEAT; furnace ignites when temperature drops below set point.
2. Fan mode: Set thermostat FAN to ON for continuous air circulation.
3. Auto mode: Fan operates only during heating cycles.
4. Standby: System waits for thermostat call for heat.
5. Lockout: Safety feature prevents operation after multiple ignition failures.

WARNING! Never operate furnace with access panels removed. Keep combustible materials away from furnace.

Maintenance Procedures

Regular maintenance ensures efficiency and longevity.

1. Monthly: Check and replace air filter as needed.
2. Seasonal: Inspect vent system for obstructions.
3. Annual: Professional inspection and cleaning of burners, heat exchanger, and flue passages.
4. As needed: Clean flame sensor with fine emery cloth.
5. Check blower wheel and motor for dust accumulation.

Care & Cleaning

Turn off power before cleaning. Use soft brush and vacuum for dust removal.

CAUTION! Do not use water or liquid cleaners. Keep electrical components dry. Never operate without air filter installed.

Regulatory Information

UL certified; meets ANSI Z21.47 standards for gas-fired central furnaces. CSA certified for Canadian market. Energy Star qualified models available. Copyright © 2025 MTI Heating Systems; all rights reserved. For technical support, visit www.mtifurnace.com or contact 1-800-555-HEAT.

Troubleshooting

Symptom	Possible Cause	Corrective Action
Furnace won't start	Power, thermostat, gas supply	Check circuit breaker; verify thermostat setting; ensure gas valve open.
No heat	Ignition failure, filter	Check for dirty filter; reset power; check status lights for error codes.
Short cycling	Dirty filter, high limit	Replace air filter; check for blocked vents; verify proper airflow.
Blower runs continuously	Thermostat setting	Check FAN setting (should be AUTO for normal operation).
Unusual noises	Loose parts, airflow	Check for loose panels; inspect blower wheel; verify ductwork clear.

Reset: Turn power off for 30 seconds, then restore. Check status lights.

Service: 1-800-555-HEAT; www.mtifurnace.com