Gas Burning Insert

Gas fireplace inserts are meant to be installed in an existing fireplace cavity, to convert a wood-burning fireplace to the one burning natural gas or propane.

To start project, measuring the opening is always the first thing to do. Typcially an opening looks like a rectangular, as shown below:

Key factors: WidthHeight and Depth (as shown in above picture)

In most cases, opening has tapered back. All gas inserts are designed with tapered back too.

In some cases, opening might look like the picture shown below

In this case, the best way is to use cardboard to make a template like the blue area in the picture above. Use this template to measure this arched opening to get a  sense of useful opening size as shown in above picture as "width" and "height"

Just go through some gas burning inserts and check the specs of gas burning insert you are interested in. Pay attention to "minimum opening" dimension shown in picture below

Compare it with your opening to see if it fits. This will quickly rule out unfit inserts so that you can focus on what fits.

Major factors to be considered while buying gas burning insert

1. Overall look

  • Gas insert is not just for heat. It's a major aesthetic focal point of a room.

  • An insert can appear either contemporary or traditional. Other decor in the room will contribute to the overall feel..

  • Search on internet or check magazine for the ideas of what kind of overall look you like 


2. Flame

  • Flame is the most important aspect of an insert. It is where money goes. Better flame always cost more.

  • Flame should be bold, vivid and bright yellow

  • Flame comes from gas burning. Bigger flame requires more gas which translates into bigger input BTU


3. Heating Capacity

  • An insert is not primary heat source for a house. ( That's what a furnace or boiler is for ! ). It provides supplemental heat

  • Insert is rated in the number of input BTU. The actual amount of heat is the output which equals INPUT BTU x EFFICIENCY

  • Heat output of insert should be adjustable


4. Efficiency

  • Although gas burning insert has improved lot in terms of efficiency, there is no high efficiency one. Anything burning into yellow flame can't achieve high efficiency


5. Blower

  • It won't increase heating capacity which is defined by burner.

  • It does speed up the heat distribution

  • It needs electricity to run


Factors related to installation

1. Chimney

  • Make sure chimney is in good condition. There must be no blockage or damage because it is where venting pipes will run through.

  • Make sure chimney is clean. If there is creosote buildup it will cause unpleasant odor.  A chimney sweep before your gas insert installation is strongly recommended.


2. Mantel

  • If mantel is made by wood or any other combustible material, there must be enough clearance

As shown in above picture, Mantel Clearance is related to Mantel Depth. The deeper Mantel Depth, the more Mantel Clearance you'll end up with. The actual number varies depending on the insert you choose. Generally a 12" clearance should be enough.

Further factors to be considered:

1. Sealed combustion (strongly recommended) 

  • It's also called " direct vent insert ". It has two liners running through chimney. One liner is for fresh air intake and another one is for exhaust.

  • It doesn't consume indoor oxygen. It's much safer ,cleaner and more efficient than those inserts with only one liner (also called B-vent insert or natural vent insert)

2. Burner media

  • There are 3 kinds of typical burner media: Log, Rock and Crystal

  • These media are made of ceramic which can sustain the high temperatures of insert.

  • Real rocks or crystals can't be placed inside insert as it might explode when set on fire.


3. Opening modification

  • To enlarge opening is not recommended since it might affect the structure of masonry fireplace, a potential safety hazard.

  • However, the width of opening can be slightly modified in most cases like picture shown below


4. Operation cost

  • If gas insert is rated as 27,000 BTU, it means this insert consumes 27,000 BTU energy per hour

  • One cubic meter of natural gas contains 27,000 BTU of energy. This insert will burn One cubic meter Natural Gas per hour.

  • Check your gas bill to find out the price of natural gas per cubic meter, let's say $0.40 per cubic meter. So the operation cost of this insert is $0.40 per hour.