A distribution blower, sometimes called a ‘convection blower’, plays the role of a warmth distributor, circulating heated air throughout the room. It moves the hot air through the stove and into the living spaces, and in some designs, it also protects electrical components from overheating by removing said hot air from problem areas. These blowers are often available as optional additions for both wood and gas stoves and fireplaces, and in some cases are considered a mandatory part. They come in various shapes and sizes and are oftentimes model specific. They are commonly used in gas and pellet stoves and fireplaces, and are sometimes available for certain wood stove models as well.
There are three typical issues you might encounter with convection blowers: they either won’t start, won’t stop, or they operate noisily. By exploring the following aspects, you can pinpoint and possibly rectify the problem. Always make sure you’re disconnecting your stove or fireplace from power before attempting any sort of troubleshooting, maintenance or repair!
Blower won’t start
Several factors could hinder the operation of your convection blower. Utilizing the wiring diagram from your owner’s manual, trace the circuit powering the blower, starting from the blower and moving backward to the power source to identify any disruptions.
- Is the blower housing blocked? Check for any blockages that could impede the impeller movement. Employ a soft brush or canned air to gently remove any creosote or debris lodged within the blower housing or obstructing the fan blade.
- Is the blower receiving power? The convection blower operates on standard wall voltage, typically between 115-120 volts. Utilize a multimeter to check the wire connections to the convection blower for voltage.
- If power is detected – Replace the convection blower.
- If no power is detected – Refer to the wiring diagram in the owner’s manual to identify any sensors or safety switches that might be halting the electricity flow to the convection blower.
- Does the blower have a heat-sensitive sensor? Many convection blowers come with a heat-activated thermodisc that waits for a minimum temperature before activating the blower, preventing it from circulating cold air. A faulty snap switch could halt the blower operation. Utilize a heat source like a hairdryer or a small butane torch to activate the switch during testing. We will post a comprehensive guide to snap disc testing soon.
Bench testing a blower
Bench testing, i.e., testing a part outside the stove, can help assess the blower’s performance independently. To perform a bench test on a convection blower:
- Disconnect the stove and the convection blower (if applicable) from power.
- Remove the blower from the stove and attach a test wire to the respective posts or wires on the motor.
- Plug the test wire into a power strip with the power off, then connect the power strip to a wall outlet.
- Secure the convection blower and switch on the power. The fan should operate with minimal noise and vibration.
Here’s a link to a video that will help you create the test wire needed for this operation: Making a Motor/Blower Test Cord
Blower won’t stop
The root of this issue often lies in a faulty control board, thermostat, or wiring within the stove.
- Is the blower governed by a temperature sensor? The sensor could be malfunctioning, keeping the convection blower running continuously. Try disconnecting one of the connections from the blower snap disc to cease the blower operation. If successful, replace the temperature sensor.
- Is the stove thermostat-controlled? A malfunctioning thermostat could cause the blower to run endlessly if it misreads the room temperature. Operate the stove manually or bypass the thermostat to check for a defective thermostat.
- Inspect the stove wiring for any short circuit or a blown fuse. Ensure all component wiring is securely connected without any cracked or frayed wires. Exposed wires could ground the blower or stove. If the fuse keeps blowing, the blower might be sending excessive power back to the control board.
If the wiring is intact, the circuit board might be defective. Consult a local technician to verify if the control board is problematic. Sometimes, the board can be rebuilt; otherwise, replacement is necessary.
Blower making unusual/excessive noises
A sharp, high-pitched screeching often points to a worn-out bearing. Generally, this calls for a motor replacement as most convection blowers have sealed bearings that can’t be oiled.
A new blower motor might be louder initially. Allow a week or so for the new blower to settle, monitoring if the noise level diminishes. Here are four questions to help diagnose excessive blower noise (i.e. noise over 70 decibels):
- Was the gasket replaced during the a new blower’s installation? A gasket can help absorb vibration and reduce noise. It’s advisable to replace the gasket whenever the blower is replaced or removed for deep cleaning.
- Were the mounting bolts tightened evenly? An uneven installation can cause the blower to wobble, resulting in a louder-than-usual noise.
- Is there a loose set screw or a bent impeller? Check the set screw holding the impeller against the motor shaft and tighten if loose. An impeller making contact with the housing might need bending back into shape or replacement. Running the blower with an out-of-balance impeller could lead to early motor failure.
- Can the noise be replicated during a bench test? Bench testing the convection blower outside the stove, as described above can help diagnose the noise source.
