A gas fireplace blower (also called a fan kit or circulation blower) dramatically increases the amount of heat delivered into your room. Without a working blower, most of the heat goes up the chimney or radiates slowly from the fireplace housing. When the blower fails, you'll notice a significant drop in how effectively your fireplace heats the space.

This guide covers how gas fireplace blowers work, how to diagnose common failures, and how to replace a blower when repair isn't practical.

How a Gas Fireplace Blower Works

A gas fireplace blower is an electrically powered fan that circulates room air around the hot firebox and pushes heated air back into the room. Here's the basic setup:

• Blower motor and fan assembly — Usually a tangential (cross-flow) or centrifugal blower mounted below or behind the firebox. It draws cool room air in through lower vents and pushes heated air out through upper vents.
• Temperature-sensing switch (snap disc or thermal switch) — Automatically turns the blower on when the firebox reaches a set temperature (typically 110-120 degrees F) and off when it cools down. This prevents the blower from running before the fireplace is warm and from blowing cold air after the fire goes out.
• Speed control (optional) — A variable speed rheostat or multi-speed switch that lets you adjust fan speed and noise level.
• Power source — The blower runs on standard household 120V AC power. It plugs into an outlet inside the fireplace or is hardwired to a junction box.

Important: the blower is completely separate from the gas system. It doesn't affect gas flow, pilot light operation, or flame behavior. A fireplace with a dead blower still produces heat — just not as efficiently.

Symptoms of a Failing Blower

Blower Won't Turn On at All

The fireplace gets hot but the fan never starts. This could be:

• A failed blower motor
• A failed thermal snap disc switch
• A blown fuse or tripped breaker
• A disconnected power plug
• A failed speed control

Blower Makes Noise But Doesn't Move Air

You hear the motor humming or buzzing but feel little or no airflow. This usually means:

• The fan wheel is broken, cracked, or detached from the motor shaft
• The motor bearings are seized — the motor tries to spin but can't
• The blower housing is blocked with dust or debris

Blower Is Extremely Loud

A blower that suddenly becomes much louder than normal typically has:

• Worn motor bearings — produces a grinding or rattling sound
• A fan wheel hitting the housing — bent blade or shifted motor mount
• Loose mounting hardware — vibration against the fireplace housing
• Debris caught in the fan wheel

Blower Runs Continuously (Won't Turn Off)

If the blower stays on even after the fireplace cools down:

• The thermal snap disc switch is stuck in the closed (on) position
• The wiring has been modified to bypass the thermal switch (some homeowners do this intentionally)
• The speed control is malfunctioning

Troubleshooting Step by Step

Step 1: Check Power Supply

Start with the simplest possibility:

• Locate the power plug or junction box for the blower. It's usually inside the lower access compartment or behind the fireplace.
• Make sure the plug is fully inserted into the outlet.
• Check the outlet itself by plugging in another device (like a phone charger). If the outlet is dead, check your circuit breaker.
• Some fireplaces have a dedicated on/off switch for the blower — make sure it's on.

Step 2: Check the Thermal Switch (Snap Disc)

The thermal switch is a round disc (about the size of a quarter) mounted on the fireplace housing near the firebox. It has two wires connected to it.

• Test with the fireplace hot: If the fireplace has been running for 15+ minutes and the blower hasn't started, the thermal switch may have failed in the open position.
• Test with a multimeter: Disconnect the thermal switch wires and test for continuity across the switch when it's hot. If there's no continuity when hot, the switch is failed open.
• Bypass test (temporary only): Disconnect the two wires from the thermal switch and connect them together (with the fireplace off). Then turn on the fireplace. If the blower starts, the thermal switch is the problem. Replace the switch — don't leave the bypass in place permanently.

Step 3: Check the Speed Control

If your fireplace has a variable speed knob:

• Turn the speed control to maximum. Some speed controls can fail at lower settings while still working at full speed.
• Test the speed control with a multimeter by checking for voltage output at different settings.
• If the blower works only at full speed, the speed control rheostat may need replacement.

Step 4: Test the Blower Motor

If power is reaching the blower and the thermal switch is good:

• Disconnect the blower and apply power directly to the motor (using a test cord or by plugging it directly into a known-good outlet, bypassing the thermal switch and speed control).
• If the motor doesn't run with direct power, the motor has failed.
• If the motor hums but doesn't spin, the bearings are likely seized. Try spinning the fan wheel by hand — if it's stiff or locked, the bearings are shot.

Step 5: Inspect the Fan Wheel

• Remove the blower assembly and inspect the fan wheel for cracks, broken blades, or debris.
• Make sure the fan wheel is securely attached to the motor shaft — the set screw can loosen over time.
• Clean any accumulated dust from the blades and housing.

Replacing a Gas Fireplace Blower

If the blower motor has failed or the entire assembly is worn out, replacement is straightforward:

Finding the Right Replacement

Blower kits are somewhat model-specific. To find the right replacement, you'll need:

• Fireplace brand and model number — This is the most reliable way to match a blower kit. See our guide on finding your model number.
• Physical dimensions — If you can't find a model-specific kit, measure the blower's overall length, width, height, and the motor shaft diameter.
• CFM rating — The airflow capacity in cubic feet per minute. Matching CFM ensures adequate heat distribution.
• Motor voltage and speed — Typically 120V AC, but speeds vary.

Browse our gas fireplace blower collection to find replacement blower kits for major brands.

Installation Steps

1. Disconnect power — Unplug the blower from its outlet or turn off the breaker if it's hardwired.
2. Remove the lower access panel to access the blower.
3. Disconnect wiring — Unplug or disconnect the blower power cord, thermal switch, and speed control connections. Take a photo first.
4. Remove mounting hardware — Blowers are typically held in place with screws, clips, or a sliding bracket system.
5. Slide out the old blower — Most blowers can be pulled straight out from the bottom or back of the fireplace.
6. Install the new blower — Slide it into position and secure with the mounting hardware.
7. Reconnect wiring — Attach the power cord, thermal switch, and speed control. Follow your photos from step 3.
8. Test — Plug in the blower, run the fireplace until it's hot, and verify the blower starts and runs quietly.

Blower Maintenance Tips

Extend the life of your gas fireplace blower with these simple maintenance practices:

• Clean annually. Use a vacuum with a brush attachment to remove dust from the fan wheel, housing, and air intake/outlet grilles. Dust buildup is the leading cause of premature blower failure.
• Listen for changes. New noises (grinding, clicking, rattling) are early warnings of bearing wear or loose components. Address them early before the motor fails completely.
• Check the air pathway. Make sure furniture, curtains, and other objects aren't blocking the intake or outlet vents. Restricted airflow makes the blower work harder and run hotter.
• Don't run the blower without the fireplace. The thermal switch prevents this automatically, but if the switch has been bypassed, running the blower without heat cycling can cause unnecessary wear.

When to Call a Professional

Blower replacement is generally a DIY-friendly repair since it only involves electricity (no gas work). However, call a professional if:

• The blower is hardwired (no plug) and you're not comfortable working with household wiring
• The fireplace housing is damaged or corroded, making blower removal difficult
• You smell burning plastic or see signs of electrical damage
• The existing wiring appears damaged, melted, or improperly modified

Shop Blower Kits

Fireplace Choice carries blower kits for Heat N Glo, Heatilator, Napoleon, Empire, Superior, Lennox, Majestic, and more. Visit our blower kit collection to find the right replacement for your fireplace model. Need help matching a blower? Contact us with your fireplace brand and model number.