Open-Fireplace to Insert Conversion

An open masonry fireplace is, thermodynamically, a net loss — it radiates a little heat into the room while pulling far more conditioned air up the chimney. Converting it to a sealed, high-efficiency insert flips that equation: the same fireplace becomes a genuine heat source that warms the room and stops bleeding your energy. Prime Chimney Experts performs insert conversions to a premium standard — correctly sized appliance, fully lined positive-connection venting, and a finished install that performs as the manufacturer intended.

The reason an open fireplace loses is simple: it's open. Combustion air and a huge volume of room air go up the flue, and most of a wood fire's heat goes with them. A high-efficiency gas or wood insert is a sealed firebox that fits into the existing opening, drawing controlled combustion air and radiating and circulating far more of its heat into the room. EPA-certified inserts reach efficiencies an open fire can't approach — but the appliance only delivers that if it's installed correctly.

The make-or-break detail is the liner. An insert must be connected to a full-length, correctly sized liner running from the appliance outlet straight to the cap — a positive (continuous) connection — so it vents safely and drafts as designed. A 'slammer' install that just sets the insert in the opening without a connected liner spills combustion products and never performs to spec. We run an insulated stainless liner sized to the insert, make the positive connection, and terminate it properly at the top.

We size and select the appliance to the space and the fuel, not to whatever's in stock. On gas inserts we make and leak-test the gas connection; on wood, we ensure the firebox and liner are matched and the clearances are right. Then we finish the surround so the insert looks integrated — a flush, intentional install, not an appliance jammed into a hole. The payoff is comfort and economy together: lower utility load, real warmth, and on wood inserts the ability to heat through an outage. We handle the permit and inspection and document the venting and any gas test.