How Does a Fireplace Blower Work?

Still debating whether or not you should install a fireplace blower? Keep reading.

A gas fireplace can make a beautiful addition to your home, whether you enjoy the romantic dance of flames at night or the warm feel of a fire on a cold night, there are literally hundreds of models and variations to choose from. While everyone's reason for choosing a gas fireplace is different, many of us purchase fireplaces for their ability to be used as a heating appliance. While it's true that some gas fireplaces are more efficient than others, most gas fireplaces are wasteful heating appliances.

Gas fireplaces are designed to vent the heat and gas created in the firebox out of your home. While a moderate amount of this heat is radiated into your home, most of the generated heat is lost through the venting process. Enter the fireplace blower and/or fan kit. Installing a fireplace blower allows you to recover this wasted heat by helping to distrubute the heated air before it's lost in the venting process. So how do these fireplace blowers work within the gas fireplace insert?

As illustrated with the image on the right, room air is drawn into the firebox through the lower louvre. Blowers are typically installed toward the rear of the firebox and push the air up and over your firebox. The air is heated as it travels around your firebox and exits your fireplace through the top louvre. The following video demonstrates this process more clearly.

Fan kit options

Not all fan kits are created equal. In fact, there are a number of options that set some fan kits apart from others. Here we will explain a few of the popular fan kit options and how they might pertain to your home setup.

Variable speed control

Variable speed control is exactly as it sounds, a way of controlling speed or RPM. In a fireplace blower application, a variable speed control is used to increase or decrease the the RPM speed at which the blower's fan is moving. You might ask yourself why this is important. Wouldn't you want the maximum amount of RPMs from the blower at all times? Well, that really depends. While it's true that a blower running at maximum speed will delivery more air flow, it's also true that the ambient noise created by the blower will be higher. A variable speed controlled blower will allow you to ajust the speed of the blower to achieve a desired level of both air flow and noise.

Our variable speed controllers not only control the RPM speed of the blower, they also include a toggle for "ON" and "OFF".

Thermostat limit switch

Also known as a Therm-O-Disc or snap thermostat, a thermostat limit switch is most commonly used in a fireplace blower application when no designated wall switch is present for the blower. When a fireplace is installed, the installer has an option of installing a wall switch to control the electrical outlet below your fireplace. When no wall switch is present, a thermostat limit switch makes it possible to control the blower's on and off operation automatically.

A thermostat may be used in applications where a designated wall switch is present. In this case, the wall switch will be left in the "ON" position so that power is always being supplied to the outlet. The thermostat will control when the blower is turned "ON" and "OFF".

So how does a thermostat limit switch work? Great question. Thermostat limit switches work by opening and closing a cicuit at 2 set temperatures. In most fireplace blower and fan kit applications, these temperatures are 90°F and 120°F. The switch closes at 120°F (blower on) and opens at 90°F (blower off). Through repeated testing, we have found that limit switches with operating temperatures of 90°F and 120°F function best in most applications. In most cases, the thermostat is flush mounted on the underside of the firebox. Some thermostats are held in place with magnetic brackets, while snap thermostats are often times held in place by a small clip on the firebox. These clips are typically provided by the manufacturer of the fireplace or insert.

High temperature wiring

In the previous section, we discussed thermostat limit switches and how they're used in fan kit applications. While most of these limit switches are flush mounted underneath the firebox, some thermostats must be mounted in a way that requires the use of high temperature rated wire. This wire is included in some of our fan kits, but can certainly be requested for custom applications.

Ball bearing & sleeve bearing motors

There's been an ongoing debate in the fireplace blower world about the differences between sleeve and ball bearing blowers. At, we believe the proof is in the pudding, which is why we're moving to all ball bearing motors. For a full discussion on this topic, read Jason's blog post below.

Fireplace Blower Kit Wiring Diagram