Installation: Icm Controls ICM2811 Integrated Furnace Control Board Instruction Guide

Content

Overview

The ICM2811 Integrated Furnace Control Board is a microprocessor-based replacement control for compatible gas furnaces. It manages the gas valve, inducer draft motor, circulating blower, and hot surface ignitor while monitoring pressure, flame, limit, and rollout safety circuits.

This furnace control board is intended for qualified HVAC technicians performing replacement, testing, and troubleshooting. It is designed as a form, fit, and functional replacement for selected Goodman and White-Rodgers ignition control boards.

Specifications

Model: ICM2811
Input voltage: 18–30 VAC, 60 Hz maximum
Hot surface ignitor relay: 6.0 amps at 120 VAC, 60 Hz resistive
Inducer relay: 2.2 FLA to 3.5 LRA at 120 VAC
Blower relay: 14.5 FLA to 25.0 LRA at 120 VAC for two-speed heating and cooling applications
Gas valve relay: 1.5 amps at 25 VAC, 60 Hz, 0.6 power factor
Operating temperature: -40° to 176°F (-40° to 80°C)
Humidity range: 5% to 95% relative humidity, non-condensing
Diagnostic indication: onboard LED fault display
Twinning: compatible with another ICM2811 control board only

Replacement Applications

Goodman: PCBBF110, PCBBF123, 0130F00005, PCBBF112, and B18099-26
Goodman variations: PCBBF110S, PCBBF123S, 0130F00005S, PCBBF112S, and B18099-26S
White-Rodgers: 50A55-743, 50A55-289, and 50T55-289

Detailed Description

The ICM2811 Integrated Furnace Control Board coordinates the furnace ignition sequence from the initial thermostat demand through burner operation and shutdown. It checks the combustion-air pressure switch, energizes the hot surface ignitor, controls the gas valve, verifies flame through flame rectification, and starts the circulating blower after flame has been proven.

Safety monitoring includes the high-limit circuit, rollout circuit, auxiliary limit circuit, pressure switch, flame sensor, and gas valve wiring. The control uses a 12-pin connection for major safety and low-voltage circuits and a 2-pin connection for the inducer blower and hot surface ignitor.

Connection Functions

P1 pin 1: limit switch output
P1 pin 2: flame-sense input
P1 pin 3: 24 VAC input
P1 pin 4: pressure-switch output
P1 pin 5: rollout-switch output
P1 pin 6: 24 VAC common
P1 pin 7: limit-switch input
P1 pin 8: common
P1 pin 9: gas-valve common
P1 pin 10: pressure-switch input
P1 pin 11: rollout-switch input
P1 pin 12: gas-valve output
P2 pin 1: inducer blower
P2 pin 2: hot surface ignitor

Safety

Turn off both electrical and gas supplies before removing or servicing the furnace control board. Failure to isolate these supplies can result in fire, explosion, electric shock, serious injury, or death.

Use electrostatic discharge precautions whenever handling the ICM2811. Disconnect furnace power, then touch a clean, unpainted metal section of the furnace chassis with your hand and tools before touching the board or wiring. Repeat the grounding procedure whenever you move around, touch an ungrounded object, or prepare to handle a replacement control.

An ESD service kit can provide additional protection. Keep the old and replacement boards separated from ungrounded objects until servicing is complete.

Before replacement, inspect the control compartment for water stains. Check nearby humidifiers, evaporator coils, and vent systems for leaks, and correct any water source before installing the new board.

Setup and Operation

Removing the Existing Control

Set the thermostat to Off or to its lowest setting.
Turn off electrical power to the furnace.
Turn off the furnace gas supply.
Remove the blower and control access doors.
Remove the control-box cover.
Label every wire before disconnecting it.
Disconnect thermostat and humidifier wiring when installed.
Disconnect line-voltage, blower, electronic air cleaner, and transformer wiring as applicable.
Remove the wiring harness from the circuit board.
Remove the screws or other fasteners securing the old board.
Inspect the control and control box for evidence of water intrusion.
Repair any leakage before continuing.

Installing the New Control

Discharge static electricity by grounding yourself to the furnace chassis.
Mount the ICM2811 using the original screws and fasteners where suitable.
Reconnect line-voltage, low-voltage, accessory, thermostat, and ground wiring.
Check all connections against the furnace wiring arrangement before restoring power.
Restore the gas and electrical supplies.
Verify the complete heating and cooling sequence before returning the furnace to service.

Heating Sequence

A call for heat applies 24 VAC to terminal W.
The inducer and optional humidifier energize, allowing the pressure safety switch to close.
The control runs a 15-second inducer pre-purge.
After pressure-switch verification, the hot surface ignitor receives power for a 9-second warm-up.
The gas valve energizes and gas enters the burners.
The ignitor lights the gas, while the flame sensor and rectification circuit check for a valid flame signal.
The initial flame-proving period lasts 4 seconds.
Once flame is proven, the ignitor turns off approximately 1 second later.
The circulating blower starts after a 30-second heat blower delay.
When the heat demand ends, the gas valve closes and the inducer runs for a fixed 15-second post-purge.
The inducer and humidifier then turn off, followed by the heat blower after the selected off-delay.

Cooling Sequence

A cooling demand applies 24 VAC to terminal Y. The control waits 5 seconds, then energizes the cooling blower and electronic air cleaner output. When the cooling demand ends, the blower and electronic air cleaner remain active for a 45-second post-purge before turning off.

Timing Values

Inducer pre-purge: 15 seconds
Ignitor warm-up: 9 seconds
Trial for ignition: 4 seconds
Additional ignition retries: 2
Inducer interpurge between attempts: 30 seconds
Inducer post-purge: 15 seconds
Heat blower on-delay: 30 seconds
Cool blower on-delay: 5 seconds
Cool blower off-delay: 45 seconds
Ignition or pressure lockout: 75 minutes
Safety recovery delay after rollout or high-limit recovery: 3 minutes

Heat Blower Off-Delay Adjustment

Move the J1 jumper to the required position to select the heating blower off-delay.

J1 pins 1 and 2: 180 seconds
J1 pins 2 and 3: 150 seconds
J1 pins 3 and 4: 120 seconds
J1 pins 4 and 5: 90 seconds

Twinning

The ICM2811 can be twinned only with another ICM2811 control board. Connect the TWIN terminals between the two furnaces, connect the common side of both 24 VAC transformers together, and bond the transformer common to earth ground. The furnace chassis must also share a ground connection.

The twinned controls are intended to operate the blowers at the same time and speed. An external AC relay is required for the heating call: its coil connects between R and W of the primary furnace, while its normally open contacts connect R and W of the secondary furnace.

LED Fault Codes

The diagnostic LED communicates operating and fault conditions through its status or flash count. Always correct the underlying furnace problem before resetting or replacing the control.

LED on: Normal operation.
LED off: Control failure. Check input voltage and the fuse; replace the control if the supply and fuse are correct but the fault remains.
1 flash: Ignition failure or soft lockout. Inspect the flame sensor, ignitor, input voltage, and transformer common-to-ground connection.
2 flashes: Pressure switch stuck closed. Inspect the pressure switch for contamination or failure.
3 flashes: Pressure switch stuck open. Check pressure tubing for obstruction, the switch, its terminals, wiring, and inducer motor.
4 flashes: Limit switch fault. Check for restricted airflow, blocked ductwork, a dirty filter, or a defective high-limit switch.
5 flashes: Flame out of sequence. Inspect the gas valve and flame sensor for intermittent operation, contamination, or failure.
6 flashes: Rollout switch fault. Check for a damaged heat exchanger, defective rollout switch, or broken rollout wiring.
7 flashes: Weak flame signal. Clean the flame sensor, verify grounding, and confirm that the sensor is properly enveloped by the flame.
8 flashes: Miswired gas valve. Check for shorted or incorrectly connected gas-valve wiring, damaged harness conductors, and pressure-switch operation.
9 flashes: Not assigned.
10 flashes: Hot and neutral reversed. Check polarity on the incoming supply and on both sides of the transformer.
11 flashes: Brownout. Measure primary and secondary transformer voltage and check for excessive transformer loading.
12 flashes: Twinning fault. Confirm shared transformer common, earth grounding, chassis bonding, and the wire between both TWIN terminals.

Troubleshooting

Flame Not Established

If the burner flame is not proven during the first 4-second trial, the control allows two additional ignition attempts. A 30-second inducer purge occurs between attempts. After three unsuccessful attempts, the furnace enters a 75-minute lockout before another ignition sequence can begin.

Flame Loss During Heating

When flame is lost while a heat demand remains active, the gas valve closes while the inducer and circulating blower continue operating. The control then attempts ignition again. Three unsuccessful attempts lead to a 75-minute lockout.

Flame Out of Sequence

This condition occurs when the control detects flame without a W heat signal. The inducer and blower engage if necessary and continue running while the fault remains present. Inspect the gas valve and flame-sensing circuit for unwanted gas flow or a false flame signal.

Pressure Switch Problems

If the pressure switch remains open during the initial purge, the control can extend the inducer pre-purge for up to 5 minutes. If the switch closes during that extended period, normal operation resumes. If it remains open beyond 5 minutes, the system enters a 75-minute lockout.

Limit or Rollout Recovery

After a high-limit or rollout switch re-closes, the control applies a 3-minute self-healing delay. The thermostat demand is then allowed to continue if the safety circuit remains closed. An open high-limit or rollout switch keeps the fault and lockout active.

Pros & Cons

Pros: Integrates ignition, blower, inducer, gas-valve, flame-sensing, and safety monitoring functions in one control.
Pros: Provides diagnostic LED codes for faster furnace troubleshooting.
Pros: Offers selectable heating blower off-delays and compatibility with a matching ICM2811 for twinned furnace systems.
Cons: Twinning is restricted to another ICM2811 control board and requires correct grounding and an external relay arrangement.
Cons: Installation involves both line-voltage and gas-furnace safety circuits, so incorrect wiring can create hazardous operation.

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Faqs

What safety steps should be followed before installing the ICM2811 furnace control board?

Set the thermostat to OFF, disconnect electrical power to the furnace, and shut off the gas supply before removing the existing control. Label every wire before disconnecting it to prevent incorrect reconnection. Protect the new ICM2811 from electrostatic discharge by touching a clean, unpainted metal furnace surface before handling the board or wiring. Reground yourself after moving around or touching ungrounded objects. Do not restore power or gas until all connections and covers are properly installed.

How do I replace an existing furnace control board with the ICM2811?

After isolating electrical and gas supplies, remove the blower and control access panels as needed. Label and disconnect thermostat, transformer, line-voltage, blower, accessory, ground, and wiring-harness connections. Inspect the control box for water stains and correct any leakage source before installing the replacement. Mount the ICM2811 with the original fasteners, reconnect each wire to the matching terminal, and verify the furnace sequence of operation. Incorrect wiring can create unsafe furnace operation.

What does the ICM2811 LED fault code indicate when the furnace will not start?

The diagnostic LED identifies the general fault area. One flash indicates ignition failure, while two or three flashes point to a pressure switch problem. Four flashes indicate a limit switch fault, and six flashes indicate a rollout switch fault. Before testing, confirm that the thermostat is calling for heat and record the LED pattern. Inspect only the related components described by the code, and treat rollout, combustion, and gas-related faults as conditions requiring qualified service.

Why does the ICM2811 keep the furnace locked out after a failed ignition?

The control allows an initial ignition trial followed by two additional attempts, with an inducer purge between attempts. If flame is not established and proven during all three trials, the ICM2811 enters a 75-minute lockout before trying again. Check the flame sensor, hot surface igniter, gas supply, wiring, grounding, and burner ignition conditions rather than repeatedly cycling power. A persistent ignition failure should be diagnosed by a qualified technician because it involves gas and combustion safety.

What should be checked when the ICM2811 reports a pressure switch fault?

A pressure switch that remains open can result from blocked tubing, restricted venting, an inducer problem, damaged wiring, or a defective switch. The ICM2811 normally permits an extended pre-purge while waiting for the switch to close. If it remains open for more than five minutes, the control enters a 75-minute lockout. Check the tubing for obstruction and the inducer connections, but do not bypass the pressure switch or operate the furnace with combustion safeguards defeated.

How can I troubleshoot a limit switch or rollout switch fault on the ICM2811?

A limit fault commonly relates to restricted airflow, blocked ductwork, or a dirty filter, while a rollout fault can indicate unsafe combustion or heat-exchanger conditions. Turn off the furnace before inspecting accessible airflow restrictions and wiring. Never jumper, bypass, or permanently reset either safety switch. After a switch recovers, the ICM2811 applies a three-minute self-healing delay. If the switch remains open, the fault and lockout continue until the underlying safety condition is corrected.

What are the normal ICM2811 furnace heating and cooling timing delays?

During heating, the inducer runs through a 15-second pre-purge, the igniter warms for about nine seconds, and the blower starts approximately 30 seconds after flame is proven. After the heat call ends, the inducer runs a 15-second post-purge, while the heating blower continues according to the J1 setting. Available heating blower off delays are 90, 120, 150, or 180 seconds. Cooling uses a five-second blower-on delay and a 45-second blower-off delay.

Can two furnaces be twinned using the ICM2811 control board?

Yes, but the ICM2811 is designed to twin only with another ICM2811. Connect the TWIN terminals between the two controls, connect and earth-ground the common side of both 24-volt transformers, and provide a common ground between furnace chassis. An external relay is also required so the secondary furnace receives the appropriate heat call. Confirm that both systems use compatible wiring and operate their blowers together before placing the installation into service.