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The Braemar THMD 520 & THMD 520X are natural gas ducted heaters, and the PCB Circuit Control Board (Modulating Control Board, MCB) with Part Number: 640365 plays a critical role in managing the operation of the heater, including functions like ignition, fan modulation, temperature regulation, and safety features. The PCB is central to the heater’s ability to maintain efficient and safe operation.
The PCB Modulating Control Board (PN: 640365) is responsible for controlling various operations in the Braemar THMD 520 & THMD 520X ducted gas heaters, which include:
Ignition Control:
The PCB coordinates the ignition process, sending signals to the spark igniter to ensure that the flame is initiated when the system is powered on.
Fan Speed Modulation:
The PCB adjusts the speed of the fan based on heating needs. It ensures the fan operates efficiently, modulating its speed based on room temperature, heating demand, and energy efficiency.
Temperature Regulation:
In conjunction with the thermostat, the PCB adjusts the burner and fan speeds to maintain the desired temperature in the room.
Safety Features:
The board monitors critical components, such as flame sensors, temperature sensors, and pressure switches, to ensure the system operates safely. If any issues are detected (e.g., no flame or overheating), the system will shut down to prevent further damage or hazardous situations.
Diagnostic and Error Codes:
The PCB includes diagnostic capabilities that can display error codes to identify faults such as ignition failure, flame sensor issues, or other malfunctions. These codes help technicians troubleshoot the system more efficiently.
Screwdrivers (Phillips and flathead)
Multimeter (for checking electrical connections)
Replacement PCB (Part Number: 640365)
Labels or camera (to record wire connections)
Turn Off Gas and Power:
Before beginning any work, turn off the gas supply and power to the heater to ensure your safety during the replacement process.
Remove the Heater Access Panel:
Use a screwdriver to remove the panel or cover of the heater, giving you access to the internal components, including the PCB.
Locate the Existing PCB:
The PCB is typically located near the burner assembly or in a dedicated section of the unit. It may be secured with screws or clips.
Disconnect the Wiring from the Old PCB:
Carefully label or photograph the wiring connections to ensure proper reconnection of the new PCB.
Disconnect the wiring from the old PCB, paying close attention to the specific connections.
Remove the Old PCB:
Unscrew or unclip the old PCB from its mounting and carefully remove it from the heater.
Install the New PCB (PN: 640365):
Place the new PCB in the same position as the old one, securing it with screws or clips.
Reconnect the wiring to the new PCB, following the labels or photo reference you took earlier to ensure proper wiring.
Double-Check Wiring Connections:
Verify that all wiring connections are secure, especially critical components like the flame sensor, spark igniter, and fan motor.
Reassemble the Heater:
Once the new PCB is installed and all wiring is connected, replace the access panel and secure it with screws.
Turn On Power and Gas:
After reassembling the heater, turn on the power and gas supply. Test the system to ensure proper operation.
Verify Heater Operation:
The heater should attempt to ignite, and the fan should modulate according to the room temperature and thermostat settings. Check for any error codes and ensure that the heater is operating without issues.
If the Braemar THMD 520 & X heater is not functioning correctly after replacing the PCB, consider these troubleshooting steps:
Possible Causes:
Incorrect wiring to the PCB.
Faulty spark igniter or flame sensor.
Solution:
Double-check all wiring connections to ensure they are correct and secure.
Test the spark igniter to verify it is working and generating a spark.
Clean or replace the flame sensor if it’s not detecting the flame properly.
Possible Causes:
Error codes usually indicate problems such as ignition failure, flame sensor issues, or fan problems.
Solution:
Consult the user manual to decode the error code(s) and troubleshoot accordingly. If the code indicates a flame failure, check the flame sensor and ignition system.
If the error indicates overheating, check the temperature sensor or fan speed modulation.
Possible Causes:
Faulty fan motor or incorrect fan speed wiring to the PCB.
Solution:
Verify that the fan speed control wiring is securely connected to the new PCB.
Check the fan motor to ensure it’s functioning properly and able to modulate its speed based on heating demand.
Possible Causes:
Temperature sensor malfunction or incorrect wiring.
Solution:
Inspect the temperature sensors to ensure they are functioning correctly.
Verify that the fan is modulating to maintain proper airflow, and check for any obstructions.
To keep your Braemar THMD 520 & X NG ducted heaters running efficiently, consider performing the following regular maintenance:
Clean Flame Sensors: Periodically clean the flame sensors to remove any soot or debris that could interfere with their ability to detect the flame properly.
Inspect Spark Igniter: Test the spark igniter to ensure it’s in good condition and properly igniting the burner.
Check Fan Operation: Clean the fan and ensure it’s running smoothly, with no obstructions that might impede airflow.
Monitor Gas Connections: Periodically inspect the gas connections for any signs of leaks or wear.
SKU | 19944 |
Brand | Braemar |