York 90 Furnace Manual

The York 90 Furnace is a high-efficiency gas furnace with AFUE ratings up to 90%, featuring advanced heat exchanger technology, electronic ignition, variable-speed blower motor, diagnostic LED system, and compatibility with various thermostat systems. Designed for residential heating applications with natural gas or propane capability, multiple venting options, and comprehensive safety features. Below are key sections for safety, features, installation, operation, maintenance, and troubleshooting.

Features at a Glance

Key components: Stainless steel heat exchanger, electronic control board, inducer motor assembly, variable-speed blower, gas valve, pressure switches, flame sensor, and diagnostic LED.

Feature	Description
Heat Exchanger	Stainless steel clamshell design for maximum efficiency
Blower Motor	Variable-speed ECM motor for quiet operation
Ignition System	Hot surface igniter with flame sensor
Venting	PVC pipe compatible for sidewall or roof venting
Diagnostic LED	Flashing code system for troubleshooting
Gas Valve	Automatic shutoff with pressure regulation
Filter System	Standard 1-inch or 4-inch media filter compatible
Thermostat Connection	Standard 24VAC connections for most thermostats
Safety Controls	Multiple pressure switches and limit controls
AFUE Rating	Up to 90% Annual Fuel Utilization Efficiency

Installation Requirements

Professional installation required. Verify local codes and obtain permits.

1. Location: Install in dry, clean area with adequate clearance for service.
2. Gas Connection: Use black iron pipe with proper sizing; pressure test required.
3. Electrical: 120VAC dedicated circuit; proper grounding essential.
4. Venting: PVC pipe system sized per manufacturer specifications.
5. Combustion Air: Ensure adequate fresh air supply per local codes.

WARNING! Gas furnace installation must be performed by qualified technician. Improper installation can cause fire, explosion, or carbon monoxide poisoning.

First-Time Setup

Initial startup must be performed by qualified technician.

1. Gas pressure adjustment: Set manifold pressure per rating plate specifications.
2. Venting verification: Check draft and verify proper vent operation.
3. Electrical connections: Verify proper voltage and thermostat wiring.
4. System checkout: Run through complete startup sequence and safety checks.
5. Customer orientation: Explain operation, filter changes, and basic troubleshooting.

CAUTION! Never attempt to adjust gas pressure or perform initial startup without proper training and equipment.

Technical Specifications

• Input Capacity: 40,000 to 120,000 BTU/hr models available
• AFUE Rating: Up to 90% efficiency
• Gas Type: Natural gas or propane (conversion kit required)
• Electrical: 120VAC, 60Hz, 5-10 amp circuit
• Static Pressure: 0.1 to 0.8 inches water column
• Venting: 2-inch or 3-inch PVC/CPVC pipe
• Sound Rating: As low as 65 dBA
• Dimensions: Varies by model (typically 21"W x 21"D x 40"H)
• Warranty: 20-year heat exchanger, 5-year parts

Controls and Settings

Integrated control board with diagnostic LED. Thermostat controls heating cycles and fan operation.

Control Board LED Codes: Steady green = normal operation; Flashing codes indicate specific faults (refer to troubleshooting section).

Temperature Control: Set via thermostat. Fan Control: AUTO or ON mode. Limit Switches: Automatic high-temperature shutdown. Pressure Switches: Verify proper venting operation. Gas Valve: Regulates gas flow with automatic safety shutoff.

Venting and Combustion Air

Direct vent system using PVC pipe for intake and exhaust.

1. Vent Pipe: Use only approved PVC or CPVC pipe; maintain proper slope.
2. Termination: Keep clear of windows, doors, and air intakes per code requirements.
3. Combustion Air: Ensure adequate fresh air supply; may require dedicated intake.
4. Clearances: Maintain required clearances to combustible materials.

Tip: Regular inspection of vent termination for obstructions is essential for safe operation.

Operating Procedures

Normal operation controlled by thermostat.

1. Heating Call: Thermostat calls for heat, inducer motor starts.
2. Pressure Check: Pressure switches verify proper venting.
3. Ignition: Hot surface igniter glows, gas valve opens.
4. Flame Detection: Flame sensor confirms ignition.
5. Blower Operation: Blower starts after heat exchanger warm-up delay.
6. Shutdown: Thermostat satisfied, gas valve closes, blower runs for cool-down.

WARNING! If you smell gas, immediately shut off gas supply, evacuate area, and call gas company or fire department.

Maintenance Schedule

Regular maintenance ensures efficiency and safety.

• Monthly: Check filter, clean if reusable type
• Seasonal: Replace disposable filter, inspect vent system
• Annual: Professional inspection and cleaning
• As Needed: Clean flame sensor, check drain system

CAUTION! Always turn off electrical power and gas supply before performing any maintenance.

Safety Features

Multiple safety systems protect against hazardous conditions.

Safety Feature	Function
Flame Rollout Switches	Detects improper burner operation
High Limit Switches	Prevents overheating
Pressure Switches	Verifies proper venting
Flame Sensor	Confirms burner ignition
Gas Valve	Automatic shutoff capability
Ignition Control	Limited trial for ignition

Regulatory Information

UL listed and ANSI certified. Complies with applicable standards for gas-fired central furnaces. Manufactured to meet or exceed industry safety standards. For technical support or warranty service, contact York International at 1-800-962-1000 or visit www.york.com.

Troubleshooting Guide

Symptom	Possible Cause	Corrective Action
Furnace won't start	Power, thermostat, door switch	Check circuit breaker, thermostat setting, door properly closed
No heat	Gas supply, igniter, flame sensor	Verify gas valve on, check for spark/flame, clean flame sensor
Short cycling	Filter, limit switch, venting	Replace filter, check for overheating, verify clear vent
Blower won't stop	Thermostat fan setting	Check thermostat fan setting (AUTO vs ON)
Unusual noises	Motor, blower wheel, inducer	Inspect for obstructions, loose components, worn bearings
LED error code	Various system faults	Count flashes and refer to service manual for specific code

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

Service: 1-800-962-1000; www.york.com