Instruction Manual for Dayton High Efficient Furnace Model 3438B

The Dayton High Efficient Furnace Model 3438B is a high-efficiency gas furnace designed for residential heating applications. This model features advanced combustion technology, electronic ignition, multi-speed blower motor, built-in safety controls, and energy-efficient operation. 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. Maintenance Procedures 7. Safety Features 8. Error Codes 9. Care & Cleaning 10. Regulatory Information 11. Troubleshooting

Features at a Glance

Key components: High-efficiency heat exchanger, electronic ignition system, multi-speed blower, integrated control board, gas valve, pressure switches, flame sensor, and limit switches.

FeatureDescription
Heat ExchangerStainless steel secondary heat exchanger for maximum efficiency
Ignition SystemHot surface electronic ignition
Blower MotorMulti-speed ECM motor for variable airflow
Control BoardIntegrated microprocessor for system control
Gas ValveModulating gas valve for precise temperature control
Pressure SwitchesSafety switches for combustion air verification
Flame SensorMonitors burner flame presence
Limit SwitchesHigh-temperature safety cutoffs
VentingPVC pipe compatible for sidewall or roof venting
Efficiency Rating95% AFUE or higher

Installation Requirements

Unpack and inspect all components. Ensure proper clearances and venting requirements.

  1. Location: Install in approved locations with proper clearances to combustible materials.
  2. Venting: Install PVC vent pipes according to local codes and manufacturer specifications.
  3. Gas Connection: Use approved gas pipe and fittings; pressure test for leaks.
  4. Electrical: Connect to dedicated 120V circuit; proper grounding required.
  5. Ductwork: Ensure proper return and supply duct sizing and sealing.

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

First-Time Setup

Initial startup and system configuration by qualified technician.

  1. Gas pressure adjustment: Set manifold pressure to specifications.
  2. Blower speed settings: Configure cooling and heating speeds for proper airflow.
  3. Thermostat configuration: Connect compatible thermostat and set parameters.
  4. System testing: Verify proper ignition, heating cycle, and safety functions.
  5. Combustion analysis: Measure flue gases for proper CO2 and O2 levels.

CAUTION! Only qualified technicians should perform initial setup and adjustments.

Technical Specifications

Controls and Operation

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

Control Board LED: Flashing patterns indicate system status and error codes.

Operation: Thermostat calls for heat → Inducer motor starts → Pressure switch verification → Hot surface ignition → Gas valve opens → Flame sensor verification → Blower motor starts after heat exchanger warm-up.

Settings: Blower off-delay, heating speeds, diagnostic mode, lockout reset.

Maintenance Procedures

Regular maintenance required for optimal performance and safety.

  1. Monthly: Check air filter; replace when dirty.
  2. Annual: Professional inspection and cleaning.
  3. Clean burners and heat exchanger.
  4. Inspect flame sensor and clean if necessary.
  5. Check vent system for obstructions.
  6. Verify gas pressure and combustion settings.
  7. Lubricate blower motor if required.
  8. Check electrical connections and safety controls.

Tip: Keep area around furnace clean and unobstructed.

Safety Features

Multiple safety systems protect against hazardous conditions.

WARNING! Never bypass safety controls. If safety switches trip repeatedly, contact qualified technician.

Error Codes

LED Flash PatternError CodeDescription
1 flashPressure switch errorCheck inducer and venting
2 flashesIgnition failureCheck gas, ignition, flame sensor
3 flashesLimit switch lockoutHigh temperature condition
4 flashesFlame rolloutCheck burners and heat exchanger
5 flashesGas valve errorCheck wiring and gas valve
6 flashesBlower errorCheck blower motor and capacitor
7 flashesControl board errorReplace control board

Care & Cleaning

Turn off power before cleaning. Keep furnace area clean and dry.

CAUTION! Do not use water or liquid cleaners. Use vacuum with soft brush attachment for dust removal.

Regulatory Information

UL listed and ANSI certified. Complies with applicable safety standards. Installation must comply with local building codes, National Fuel Gas Code (NFPA 54), and National Electrical Code (NFPA 70). For support, contact Dayton Technical Support at 1-888-DAYTON1 or visit www.dayton.com.

Troubleshooting

SymptomPossible CauseCorrective Action
Furnace won't startPower, thermostat, door switchCheck circuit breaker, thermostat setting, door switch engagement
No heatGas supply, ignitionVerify gas valve on, check for ignition attempts
Short cyclingDirty filter, airflowReplace filter, check for blocked vents/registers
Blower won't stopThermostat, control boardCheck thermostat fan setting, control board relay
Unusual noisesMotor, blower wheelInspect blower assembly, motor bearings
Error code flashingSystem faultRefer to error code chart; reset if safe

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

Service: 1-888-DAYTON1; www.dayton.com

Instruction Manual for Dayton High Efficient Furnace Model 3438B © - All Rights Reserved 2025