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Converting a Wood-Burning Fireplace to Gas
Gas is the most common reason homeowners give up wood in an existing fireplace. The conversion can be as simple as a log set or as involved as a vented insert with a new liner and a gas line. This guide walks through the options and the chimney questions that come before any of it.
The short answer: A wood fireplace can be converted with vented gas logs, a gas insert, or sometimes a ventless unit. Each changes how exhaust leaves the house, so the chimney should be inspected first, and the gas line and any permits are handled by licensed professionals.
A gas question that is really a venting question
Most of the cost, effort and risk in a conversion lies in the chimney rather than the flame. Wood smoke is hot, buoyant and plentiful, so a large masonry flue handles it well. Gas exhaust is cooler and smaller in volume, and it carries a great deal of water vapor. A flue that suited wood may now be too wide, too cold and too damp.
The Chimney Safety Institute of America advises a professional inspection of the chimney and venting system before any new hearth appliance goes in, including adding gas logs to a wood fireplace. It lists the checks: fuel compatibility, flue condition, flue size, chimney height and home airtightness. It also warns that skipping this step risks carbon monoxide entering the house, chimney fires and poor performance.
Start there. Everything else is a choice among options that the inspection either allows or rules out.
Your three main options
1. Vented gas logs
A burner and ceramic logs go on the firebox floor. The fireplace remains a fireplace, and the flue stays open. One manufacturer’s manual says the damper must be fully opened while burning, with a clamp or stop so it cannot close fully. The fireplace has to be in good working order with a functioning flue. Most of the heat goes up the chimney, so these are for ambiance.
2. Gas insert
A sealed unit fits into the opening and vents through its own system. According to Energy Trust, inserts can convert an existing masonry fireplace to gas using direct-vent or natural-vent systems. They give meaningful heat. CSIA says replacing a wood insert with a gas insert generally requires venting modifications. See gas logs versus gas inserts for the full comparison.
3. Ventless (vent-free) logs
These have no chimney connection. Energy Trust says ventless appliances are not recommended as a home heating source because combustion byproducts are not vented outside, which can affect indoor air quality. Whether one is allowed in your home is a question for the local code official. We do not recommend them as a default.
What the process usually looks like
- Inspect the chimney. A sweep examines the flue, damper, firebox and smoke chamber, usually including a camera view. See chimney camera inspections.
- Clean it. Soot, creosote and debris are removed. The Regency manual calls for cleaning the flue, damper and firebox and having a sweep inspect before logs are installed.
- Decide the appliance. Logs, insert, or something else, chosen with the inspection results in hand.
- Repair or line the chimney if needed. Cracked tile, open joints or an oversized flue are addressed. See flue liner repair, replacement and HeatShield options.
- Run the gas line. A licensed professional installs the line and a shutoff valve, then tests the connections with a soap solution, not an open flame, per the logs manual.
- Install the appliance and finish. Burners, logs or insert, trim and any block-off plates are set according to the manual.
- Test and explain. Draft, operation and alarms are checked, and you should be told how to run and service the unit.
The order matters. Buying an insert before the inspection is the most common way to end up with equipment that does not fit.
Flue and damper changes
For vented logs, the damper generally stays in place and is held open. For an insert, the damper may be removed, blocked or sealed, depending on the unit and the installer’s plan. Do not alter a damper to suit a project without checking the appliance instructions.
The flue may need a liner. CSIA states that a masonry chimney without a liner needs one for any new appliance, and that converting from wood to gas often requires chimney or venting modifications such as adding a liner. A smaller liner may be needed because the existing flue can be too large.
Chimney height also matters. CSIA notes that a chimney that is too short may not create enough draft. For vented logs, the installation manual sets a minimum chimney height and clearance to taller objects nearby, and tells you not to install in a fireplace below a stated height. Read your product’s manual rather than relying on a general number, and ask the installer to confirm.
Gas line, permits and who does what
Gas line work belongs to licensed professionals. Energy Trust advises using a licensed, qualified contractor and says improper venting or gas line work is the most common source of problems. The Regency manual also says to follow the applicable gas code and local codes, and notes that a certified installer may be required to keep a warranty valid.
Permits and inspections vary by municipality and by the scope of work. New Jersey’s Department of Community Affairs lists construction permit forms, including one for chimney verification when replacing fuel-fired equipment, with filing through the local construction code office. Whether your conversion requires a permit is a question for that office and your contractor. Our guide to permits and contractor documents for chimney work in NJ lists what to ask for and keep.
Some projects involve more than one trade: a chimney professional for the flue and liner, and a licensed plumber or gas fitter for the gas line. Ask who is responsible for coordinating the permits.
Odor, soot and safety after conversion
Some smell is common when a new gas appliance runs for the first time, as manufacturing oils and finishes burn off. A persistent gas smell is different. If you smell gas, do not operate switches or flames, leave the house, and call your gas utility or emergency services from outside.
Exhaust odor, soot staining, lingering fumes or a carbon monoxide alarm all mean stop using the appliance and have it checked. The gas logs manual says that if fumes or soot enter the room with the damper open, you should stop using the logs and have a technician correct the draft. Our guide to carbon monoxide and your fireplace explains the risk.
- Install carbon monoxide alarms near the fireplace and outside sleeping areas.
- Keep the glass front of an insert out of reach of children and pets, since Energy Trust warns it can cause serious burns.
- Do not burn wood in a fireplace with decorative gas logs, per the manufacturer’s manual.
- Schedule annual professional service.
What this guide cannot tell you
This guide cannot say whether your particular fireplace can be converted, which option fits it, or what a conversion requires in your town. Those depend on the firebox, the chimney, the gas supply and the product’s instructions. Check the appliance manual and your local code official.
AM provides chimney inspection, cleaning, repair and liner installation, and explains findings and options before any work begins. Gas appliance installation and gas line work should be handled by the licensed trades the manufacturer and your municipality call for.
Frequently asked questions
Can I convert my fireplace without a liner?
CSIA says a masonry chimney without a liner needs one for any new appliance. Wood-to-gas conversions often require chimney or venting changes as well. An inspection will say what your chimney needs.
Will gas logs heat my room?
Only a little. With the damper open, much of the heat goes up the chimney. An insert is the option designed to heat.
Do I still need my chimney cleaned after converting?
Yes, annual inspection is still advised for gas systems. Debris and nests can block a gas-appliance chimney.
Can I switch back to wood later?
Sometimes, depending on the option you choose. Manuals for decorative gas logs warn against burning wood with the burner installed, and inserts generally change the fireplace for good.
Related reading
- Gas vs wood fireplace venting: the basics
- Fireplace inserts explained: wood, gas and pellet
- Chimney inspection
- Chimney liner installation and replacement
- Direct-vent, B-vent and vent-free gas appliances compared
Sources
- CSIA, inspection before a new hearth appliance: pre-installation inspection, liner need, flue size, chimney height
- Energy Trust, gas fireplaces: insert and vent types, ventless caution, licensed contractor, hot glass
- Regency vented gas logs manual: damper open, flue cleaned and inspected first, gas connection testing, no wood burning
- NJ DCA construction permit forms: existence of chimney verification form, filing through local code office
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