Intertherm Furnace Service Manual

The Intertherm Furnace is a high-efficiency heating system designed for residential and light commercial applications. This service manual covers installation, operation, maintenance, and troubleshooting procedures for various Intertherm furnace models. Below are key sections for safety guidelines, technical specifications, installation procedures, maintenance schedules, and troubleshooting guides.

1. Safety Precautions 2. Technical Specifications 3. Installation Procedures 4. Operation Guidelines 5. Maintenance Schedule 6. Component Overview 7. Electrical Connections 8. Gas Line Connections 9. Venting Requirements 10. Troubleshooting Guide 11. Parts List

Safety Precautions

Critical safety information for proper furnace installation and operation.

Hazard Type	Precaution
Fire/Explosion	Keep combustible materials away from furnace; ensure proper clearance
Carbon Monoxide	Install CO detectors; ensure proper venting; check for leaks
Electrical Shock	Disconnect power before servicing; use proper grounding
Burn Hazard	Allow furnace to cool before servicing; wear protective gloves
Gas Leaks	Check all connections with soap solution; never use open flame

Technical Specifications

Detailed technical data for Intertherm furnace models.

Input Capacity: 40,000 - 120,000 BTU/H
Efficiency Rating: 80% - 96% AFUE
Voltage Requirements: 120V AC, 60Hz
Gas Type: Natural Gas or Propane
Gas Pressure: 3.5" WC Natural Gas, 11" WC Propane
Airflow: 800 - 2000 CFM
Dimensions: Varies by model (consult specific model data)
Weight: 80 - 150 lbs

Installation Procedures

Step-by-step installation guidelines for proper furnace setup.

Location Selection: Choose well-ventilated area with proper clearances
Uncrate and Inspect: Check for shipping damage; verify all components
Position Furnace: Level unit on solid foundation or mounting brackets
Connect Venting: Install flue pipes according to local codes
Gas Line Connection: Use approved pipe and fittings; pressure test
Electrical Wiring: Connect power and thermostat wires per diagram
Ductwork Connection: Secure supply and return air ducts
Startup Procedure: Follow initial startup checklist

WARNING! Installation must comply with local building codes and manufacturer specifications. Professional installation recommended.

Operation Guidelines

Proper operation procedures for optimal furnace performance.

Thermostat Setting: Set to desired temperature; use programmable features
System Startup: Allow 30-60 seconds for ignition sequence
Normal Operation: Monitor for consistent heating and airflow
Seasonal Operation: Perform seasonal maintenance checks
Shutdown Procedures: Follow proper off-season storage guidelines

CAUTION! Never operate furnace with access panels removed or safety devices bypassed.

Maintenance Schedule

Recommended maintenance intervals for reliable operation.

Maintenance Task	Frequency	Procedure
Air Filter Replacement	Monthly	Replace or clean filter; check airflow
Blower Cleaning	Annually	Clean blower wheel and housing
Heat Exchanger Inspection	Annually	Check for cracks or corrosion
Burner Cleaning	Annually	Clean burners and ignition system
Vent System Inspection	Annually	Check for blockages or damage
Gas Pressure Check	Annually	Verify proper gas pressure settings

Component Overview

Detailed description of major furnace components.

Heat Exchanger: Transfers heat from combustion to air stream
Burner Assembly: Gas combustion system with ignition control
Blower Motor: Circulates air through duct system
Gas Valve: Regulates gas flow to burners
Control Board: Electronic control system for operation
Limit Switches: Safety devices to prevent overheating
Flue Collector: Directs combustion gases to vent system
Filter Rack: Holds air filtration system

Electrical Connections

Wiring diagrams and electrical connection procedures.

Power Supply: Connect 120V AC power to designated terminals
Thermostat Wiring: Connect R, W, G, Y, C wires as required
Grounding: Ensure proper equipment grounding
Control Circuit: Verify low-voltage wiring integrity
Safety Circuits: Test limit switches and pressure switches

WARNING! Always disconnect power before servicing electrical components.

Gas Line Connections

Proper gas line installation and testing procedures.

Pipe Sizing: Use appropriate pipe size for BTU rating
Connection Points: Use approved pipe dope or tape on threads
Sediment Trap: Install drip leg before gas valve
Pressure Testing: Test system at 14" WC for 10 minutes
Leak Check: Use soap solution to check all connections
Final Connection: Connect to furnace gas valve

CAUTION! Gas line installation must be performed by qualified technician.

Venting Requirements

Venting system specifications and installation guidelines.

Vent Material: Approved Category I vent pipe
Clearances: Maintain required clearances to combustibles
Vent Size: Match furnace flue outlet size
Termination: Proper roof or wall termination required
Slope: 1/4" per foot upward slope toward termination
Support: Secure vent pipes every 4 feet

Troubleshooting Guide

Common furnace problems and solutions.

Symptom	Possible Cause	Corrective Action
No Heat	Thermostat, power, gas supply	Check thermostat setting; verify power; check gas valve
Insufficient Heat	Dirty filter, low gas pressure	Replace filter; check gas pressure; verify airflow
Frequent Cycling	Dirty filter, limit switch	Clean/replace filter; check limit switch operation
Blower Not Working	Motor, capacitor, control board	Check motor; test capacitor; verify control signals
Burner Won't Ignite	Igniter, gas valve, pressure switch	Check igniter; verify gas flow; test pressure switch
Unusual Noises	Blower, motor bearings, ductwork	Inspect blower wheel; check motor; secure duct connections

Parts List

Common replacement parts for Intertherm furnaces.

Heat Exchanger Assembly
Burner Assembly
Gas Valve
Ignition Control Module
Blower Motor
Control Board
Limit Switches
Pressure Switch
Flame Sensor
Air Filters
Blower Wheel
Inducer Motor

Service Support: 1-800-INTERTHERM; www.intertherm.com