Sierra Flame INS-FM-34 34-Inch Electric Fireplace Insert, Steel Surround

Swap the Wood Fire for One That Runs on a Plug

The Sierra Flame INS-FM-34 is Amantii's larger electric fireplace insert. It fits inside a wood-burning fireplace you already have, brick and mortar or factory-built metal, and finishes the front with a black steel surround big enough to cover a worn face. Behind its glass is a log set lit by an LED flame you can watch on its own or with the heater running. Think of it as replacing the fire, not the fireplace: the chimney and hearth stay, and the firewood goes.

Model Name Says 34 Inches, the Surround Says 42

Both numbers are right, because they measure different parts. Amantii names the unit for its front frame, drawn at 34 3/4 inches across in the manual. The steel surround that covers the fireplace face is 42 inches wide and 30 inches tall. The box that slides into the firebox is 33 1/8 inches wide.

For fit, the opening is what counts. Amantii's 2021 manual gives a rough opening of 35 1/8 inches wide by 24 inches tall for this model, so measure your firebox opening against that first. Then check that a 42-inch-wide surround will cover the brick or metal face you want hidden.

Best for Wider Fireplaces and One-Room Heating

Choose this size when your opening clears those dimensions. A narrower fireplace takes the Sierra Flame INS-FM-30 instead. The two carry an identical heater, so the bigger model gives you a larger fire to look at rather than more warmth.

Amantii rates it for zone heating of up to 500 square feet, which in practice means the room you are sitting in. It is not designed to heat a whole house.

Remote Sets the Flame Color, Heat and Canopy Light

The included remote switches the heater between low, high and auto. Auto steps between full and half power to keep the room near 72 to 77°F and shuts the heater off when it gets warmer than that. The flame blends yellow, orange and red, while the canopy light can hold a single color or flash through Amantii's full set. Buttons on the lower left of the unit cover the basics if the remote goes missing.

Warm air rises out of the top of the overlay instead of blowing through a front grill, so the face stays clean, and the flame keeps running with the heat off on warm evenings.

Seal the Chimney and Choose Plug or Hardwire Up Front

Shut and seal the damper so outside air does not come down the chimney around the insert, and set the unit level on its four leveling legs. Amantii asks for 1 inch of space on the sides and back and 3/8 inch on top. Decide on power before installation day. The cord exits on the left and reaches a standard grounded outlet, which Sierra Flame's earlier manual allows inside the fireplace as long as it is a jacketed, code-approved box and not above the insert. For a cordless install, a licensed electrician connects it directly at the left-side junction block, and that is also the moment to wire an optional 24-volt wall thermostat.

Know the limits, too. There is no Wi-Fi or phone app on this version, and the manual warns against switching the heater with an outside timer or smart plug. Amantii's current manual gives no clearance figure for a mantel or TV above, so tell us what is over your fireplace and we will get Amantii's answer before you order.

Optional accessories: trade or mix the sable glass bed with Amantii decorative fire glass, or lay Amantii Ember or Ice media under the logs for a different look.

WARNING: This product can expose you to chemicals including lead, which is known to the State of California to cause birth defects or other reproductive harm. For more information, go to www.P65Warnings.ca.gov.