There are three basic types of Gas Fireplaces and Stoves:
Top Vented Gas Fireplaces and Stoves are designed to vent through the
roof, similar to the way woodstoves and wood fireplaces do. This chimney
can be an existing masonry or metal chimney, or a newly installed B-Vent
(special aluminum gas pipe).
Most units require a 4" or 5" diameter piping to properly vent the leftover combustion products. When installing one of these units into an existing chimney, the chimney should be downsized by lining it with an approved flexible connector equal in size to the exhaust pipe of the appliance.
Many different finishes, including marble, brick and mantels can be installed to dress up the installation. Remote controls, wall thermostats, blowers and wall switches are just some of the popular options.
Top vented units are a popular choice in new construction, single story homes and as a retrofit into existing chimneys. For two story or more difficult installations, a direct vent or ventless may serve you better (see below).
Top Vented Fireplaces sell for $600 to $2500 - Installation prices will vary due to the many venting and decoration options.
Direct Vented Fireplaces and stoves offer a convenient option - No chimney
is needed - just a hole through the wall behind or right above the
appliance. This gives quite a bit of installation flexibility, such as locating
the unit below a big picture window. This direct vent pipe is really two
pipes, one inside the other. The outer wall sucks in air from outside to
be used in burning the Gas. The inner pipe then returns the flue gases back
outside. This "sealed" system is very safe and efficient because
no air from inside the home is being used for combustion.
Direct-Vent Side View
As with the Top Vented units, the installation finishes and options are many.
Direct Vent Fireplaces and Stoves sell for $1000 to $2500, including the venting pipe. Installation can run $600 for the basic Gas Hookup and Venting - plus the cost of Hearth, Mantels and finish work.
Ventless Stoves and Fireplaces have become very popular in the last few years.
No chimney or vent is needed with these appliances, so the installation costs
are minimal. The units are "zero clearance" (right against a wall)
or close clearance (a few inches away) allowing a great flexibility in the placement.
These Ventless Products pass all current safety and emission standards. They are equipped with an ODS (oxygen depletion sensor) pilot light system that has been almost flawless in it's safety record, even with millions of these appliances installed.
Still, some states , such as California, Mass., and others do not allow the use of ventless products. Many hearth experts, and even some of the Ventless manufacturers state that these units are for occasional , attended and supplementary use. Being an open fire (no glass), it is probably prudent to use your Ventless Fireplace only when you are in the room with it.
Ventless Stoves operate at 99% efficiency, and are available in sizes from 10,000 to 40,000 BTU/Hr output. Prices start at $400 and run up to $1500, with finish (marble, mantels, etc) adding to the installed cost.