Conversion · Liner · Gas Insert · Eastside WA
Most wood-burning fireplaces on the Eastside go unused. Puget Sound burn bans, the prep and cleanup of seasoned wood, and the unpredictability of actual heat output wear people down. Converting to gas eliminates all of those — and most Eastside masonry fireplaces are stronger conversion candidates than homeowners assume. The existing firebox opening stays. The existing chimney becomes the vent path. What changes is what comes out of it.
The first question is what you’re starting with
Eastside homes built across four decades have very different fireplace situations. Masonry fireplaces, factory-built prefabs, and homes with no existing fireplace all convert differently — sometimes to an insert, sometimes to a new direct-vent build. A walkthrough confirms which path applies before anything else.
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The strongest conversion candidates. Full masonry fireboxes with a brick or stone surround and a masonry chimney above are standard in Bellevue’s established neighborhoods — Newport Hills, Eastgate, Somerset, Lakemont, and downtown Bellevue. A gas insert slides into the existing firebox opening; a flexible stainless liner runs up the existing chimney to handle combustion exhaust. No new exterior penetration. No new chase framing. The chimney structure stays in place.
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Factory-built zero-clearance units — a steel firebox in a framed chase with a lightweight metal chimney above — are common in Eastside homes built between 1985 and 2005. These can convert to gas, but insert selection is brand-specific: the insert dimensions have to match the existing firebox opening, and the existing chase has to be in serviceable condition. If the prefab is in poor condition or the firebox opening doesn’t accommodate any available insert, the path becomes a new direct-vent new-build.
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No existing firebox doesn’t mean no path to gas. A new-build direct-vent gas fireplace — which vents through an exterior wall with a co-axial two-pipe system and requires no chimney — is the standard approach. The project scope is larger (new firebox opening, new venting assembly, full surround build), but it opens up format options that a conversion into an existing firebox can’t accommodate: linear wide-format units, see-through fireplaces, and fireplace placement in rooms with no chimney above.
The part most homeowners don’t expect
When a gas insert converts a masonry fireplace, the existing chimney doesn’t just continue working as-is. A flexible stainless co-linear liner is installed from the insert collar up through the existing flue to a new crown termination cap. This liner is the dedicated vent for the gas appliance — sized to the insert’s BTU output and vent specifications, not the old wood-burning flue dimensions.
What the written estimate covers
A complete gas conversion estimate isn’t just the insert price. See a full breakdown of cost drivers here. The five items below appear as explicit line items on every Prime estimate.
The gas insert
The appliance itself — make, model, BTU output, flame presentation, and manufacturer warranty. Unit selection happens in the design conversation, before the estimate is written. We discuss the room size, heat objective, and design preference. The insert is chosen based on those inputs, not based on what’s in stock.
Stainless liner assembly
The flexible co-linear liner, sized to the insert’s venting specifications. Includes the liner itself, the connection to the insert collar, and the new crown termination cap. This is a dedicated component of the conversion — not an optional upgrade.
Gas line connection
A new gas supply branch from the nearest gas line to the insert location. For most Eastside homes, the nearest gas line is close — range, furnace, or dryer. For rooms farther from the meter, the run is longer. The estimate states the scope of gas line work explicitly.
Surround and mantel scope
Whether the surround is a simple tile face around the insert, a new mantel installation, or a full custom surround — this is the item most homeowners adjust the most during the design conversation. The existing wood-fireplace trim usually doesn’t suit a gas insert’s proportions, so most conversions include some surround work.
Permits and inspection
The City of Bellevue requires a gas piping permit and mechanical permit for every gas conversion. These are included in the estimate as a line item. Permits are pulled before installation begins. The City inspection happens before the fireplace is commissioned — not as an afterthought.
Google reviews
“The technician found a minor problem that I would have overlooked during a chimney inspection. He gave me straightforward repair options and a clear explanation without putting any pressure on me.”
Kathleen Kimura
Verified Google review
“We noticed some cracks in the chimney and weren't sure how serious they were, but they carefully inspected everything and only recommended the repairs that were actually needed. The whole process was smooth and well-organized, and the chimney now looks solid and secure again.”
Emanuel Leavitt
Verified Google review
“I'm really impressed with the service we received for our new pellet stove installation. Everything was done carefully to spec, and they took the time to clearly explain the safety steps, which made us feel confident using it.”
Bruce Cropper
Verified Google review
“The technician spotted minor damage to my chimney crown that I hadn't noticed and quickly took care of it. He explained the repair options clearly and made sure everything was solid, which I really appreciated for his honesty and skill.”
Jean Hill
Verified Google review
“Prime Chimney was suggested by a neighbor, and I now see why. They were easy to book, arrived on time, and completed a thorough job. The technician was courteous and left no mess. Our chimney is clean, safe, and ready for the colder months. Wonderful local enterprise!”
Manuel Laporte
Verified Google review
Common questions
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Free in-room walkthrough
We assess the existing firebox, confirm candidacy, and put together a fixed written estimate with every line item — insert, liner, gas line, surround, and permits — before any work begins.
