Converting a Wood Fireplace to Gas

The three conversion paths

For a deeper comparison of the appliances, see gas logs vs. gas inserts.

Option 1: vented gas logs

Vented logs are the simplest conversion. A burner and ceramic log set sit on the hearth, and exhaust rises up the existing chimney. One manufacturer's manual requires installation in a working solid fuel fireplace, a fully open damper while burning, a damper clamp to keep it from closing fully, and open glass doors while operating. Because the chimney stays the exhaust path, its condition still matters as much as it did with wood.

Vented logs also send most of their heat up the chimney, just as an open wood fire does. If you hoped the conversion would warm the room, logs may disappoint. They suit homeowners who want the look of a fire without hauling wood, and who are content with modest warmth near the hearth.

Option 2: vent-free logs

Vent-free logs are designed to burn without venting to the outside. A manual we reviewed describes an oxygen depletion sensor, a room-volume formula limiting the burner's input, a prohibition on larger units in bedrooms and bathrooms, and a warning that state and local codes may allow only vented operation. Check with your town before choosing this route. The manual also requires the chimney to be cleaned of soot and creosote before installing in a wood-burning fireplace.

Option 3: a direct-vent gas insert

An insert is a sealed gas heater that fits into the fireplace opening. Direct-vent inserts usually run two flexible pipes up the chimney, one for exhaust and one for outside combustion air, ending in a termination cap. An insert manual we reviewed requires the chimney to be clean and in good working order, sets minimum flue sizes and a height range, and allows the damper to be blocked open or removed. Another manufacturer prohibits connecting a gas insert to a flue serving a separate solid fuel appliance. See fireplace inserts explained.

An insert is the most involved conversion. It needs an opening that fits the unit, a chimney of suitable size and height for the vent system, a gas line, and often electrical power for a blower or controls. In return, it closes off the drafty fireplace opening and puts much more of the heat into the room.

Preparing the chimney

A fireplace that has burned wood for years has creosote in the flue and smoke chamber. Gas appliance manuals call for cleaning the chimney before installation, partly to prevent creosote odors from entering the home. The chimney should also be inspected for damage that would affect the new appliance. CSIA lists the addition or replacement of an appliance and a change in fuel type as reasons for a Level 2 inspection, which includes a video examination of the flue.

Problems to fix before conversion often include a cracked crown, a missing cap, damaged flue tile, or a deteriorated firebox. A gas flame does not stop water from entering a chimney, and a poor cap still lets in animals and debris that can block a gas appliance's vent. CSIA notes that gas-served chimneys still need annual inspection for that reason.

How to decide

• How will you use it? A few evenings a year for atmosphere points toward logs. Regular winter heat points toward an insert.
• What does your fireplace allow? Masonry fireplaces accept most options; factory-built units are limited by their manuals.
• What does your town allow? Ask about vent-free appliances and permit requirements before you shop.
• What condition is the chimney in? Repairs needed now will shape the budget and the timeline.

The gas line

Every conversion needs a gas supply at the fireplace, with a shutoff valve and connections made to code. If no line reaches the fireplace, running a new one is work for a plumber or your gas utility. Chimney 911 does not run or install new gas lines; we connect gas logs, gas fireplaces and inserts to an existing line. If your home has no gas service, propane may be an option, with its own tank and installation requirements. The appliance must be set up for the fuel it will burn.

Permits in New Jersey

New Jersey towns commonly treat gas appliance installation and gas piping as permit work. One New Jersey borough's permit list includes installing a gas insert into a fireplace as an item that requires a permit. Requirements vary, so check with your local construction office before work begins.

Factory-built fireplaces

If your fireplace is factory-built, its manual decides what can be added. One manual we reviewed prohibits installing a gas insert without written authorization from the fireplace manufacturer. Gas log sets may also be limited to specific approved models. See factory-built fireplaces: care and limits.

Next step

After any conversion, a gas fireplace still needs annual service and a check of its chimney or vent. Install and test carbon monoxide alarms as their manufacturers recommend; if one sounds, leave the house and call 911. See carbon monoxide and your chimney.

Thinking about converting? Start with an assessment of the fireplace and chimney. Request a visit, and see our gas log and gas fireplace installation and chimney liners services.

Questions homeowners ask

Sources

1. Masonry Fireplace Industries Virginiana vented gas log manual
2. Grand Canyon Gas Logs vent-free log set manual
3. Kozy Heat Nordik 34i gas insert installation manual
4. Valor LX1 co-linear venting specification
5. CSIA: The Three Levels of Chimney Inspections
6. Borough of Allendale, NJ: Do I Need a Permit?

This guide is general information. It can't diagnose a specific chimney; an inspection can.