Interested in a gas fireplace? Read on to learn about the different styles, how they work, what
venting is required, where to place them, and which models are most in-demand.
There are three main types of gas fireplaces available: Direct Vent, Ventless (Vent-Free), or B-
Vent. The most common option is Direct Vent. Ventless fireplaces don’t need a chimney and give you more options for places it can be installed. B-Vent, although less popular than the other two, has the best flame appearance.
Direct Vent Fireplaces
WHAT IS A DIRECT VENT GAS FIREPLACE?
Direct vent fireplaces offer a safer and more efficient alternative to other wood-burning and gas fireplaces. Direct Vent fireplaces are sealed with a firebox and attached venting system. The firebox is sealed by the glass and a safety screen that helps prevent accidentally touching the hot surface. Safety screens are something those with children or pets will appreciate.
Two things happen with direct vent systems
- Outside air is drawn into the firebox for combustion
- The gases resulting from combustion are vented from the home.
Having this process happen in a sealed environment helps maintain indoor air quality, protects
home efficiency, and allows the fireplace to function effectively.
How air enters & exits your home
The two options for venting are coaxial & colinear. Both systems use two pipes but differ in their
Co-Linear Venting (pipes next to each other)
Two pipes running parallel are co-linear systems. One pulls in air to assist with combustion
while the other exhausts the byproducts. They can only be terminated vertically so if you have an
existing chimney this might be a good option for you.
Co-Axial Venting (pipe inside a pipe)
Instead of being two completely separate pipes, a co-axial system is a pipe within a pipe. While
the outer pipe pulls in outside air to assist with combustion the inner pipe expels combustion
Cool air enters the firebox through the convection intake located at the bottom of the unit. Air is circulated in the firebox and then heated air is released back into the room. A blower is an optional fan that can increase the amount of hot air pushed into the room.
A heat dump system can be installed on some fireplaces. This will draw heat from the fireplace & transfer or “dump” it into another area.
The heat being “dumped” can lower clearances above the fireplace. Clearance is the safe distance combustible materials need to be to avoid starting a fire. Low or zero clearances give you more options for placement of the unit and the surrounding decorations & technology you want to have.
WHERE CAN I INSTALL A DIRECT VENT FIREPLACE?
Customers have put direct vent fireplaces in pretty much every room including basements. Every state and city have their own specific codes. Make sure to verify that a Direct Vent fireplace is allowed in the location you want.
ARE DIRECT VENT FIREPLACES SAFE?
When installed and serviced annually by licensed professionals direct vent fireplaces can be safe and efficient. Direct Vent fireplaces use outdoor air to burn and they are sealed off. This means that you don’t need to worry about combustion by-products polluting your indoor air. You should still have carbon monoxide detectors in place.
Also, it is important to ensure that the glass front or safety barrier is in place when the fireplace is operating. The fireplace won’t work correctly and could lead to combustion gasses entering the house.
You can choose from a variety of Direct Vent fireplace styles: corner, linear, see-through, and multi-sided (peninsula), as well as single or double-sided. Due to its sleek design and modern appeal, linear models are today’s most preferred style.
VENTLESS GAS FIREPLACES
WHAT IS A VENTLESS FIREPLACE?
Ventless gas fireplaces, also known as Vent-Free, are completely freestanding and do not require a chimney or venting system. Because there is no venting hot air does not escape outside the house. This makes Ventless fireplaces a popular option as a supplemental heat source.
HOW DO VENTLESS FIREPLACES WORK?
To assist combustion, cool room air is drawn into the firebox. Air flows around the firebox, before returning to the room as heat.
The ventless gas fireplace is highly efficient, which means that there are very few gases left after combustion. The majority of the remaining gases will be water vapor or carbon dioxide. High levels of carbon monoxide and other dangerous gases will not be present.
Because Ventless fireplaces use oxygen to burn, water vapor is created. This can cause condensation on your windows and throughout the house.
A little moisture is a good source of humidity in the winter, but more can lead to mildew and mold growth.
You can open a small window to restore equilibrium to your room if you feel there is too much moisture. A hygrometer can also be installed to monitor the moisture levels in your home.
To maintain normal humidity and oxygen levels, it is recommended that you only use your Ventless fireplace one hour at a time and no more than 4 hours in a day.
Just like Direct Vent fireplaces, Ventless fireplaces can be equipped with safety barrier screens to protect from injury. Although Ventless fireplaces do not have to be equipped with a safety barrier screen they are a wise investment.
WHAT KIND OF VENTING DO I NEED?
No venting is required.
WHERE CAN I INSTALL A VENTLESS FIREPLACE?
Ventless fireplaces have greater restrictions regarding location, size, media modification, and elevation.
Since the air inside the room is being circulated through the fireplace oxygen depletion and air quality are concerns. Ventless fireplaces cannot be used in small rooms with a limited oxygen supply.
Ventless gas logs must be arranged in a particular pattern to prevent the flames from touching them and causing harmful byproducts to flow directly into your house.
The manufacturer calibrates ventless gas fireplaces to burn a certain air-to-gas ratio. This leads to efficient combustion and leaves very few byproducts.
You will need to adjust the gas output of your fireplace if you reside in an area at higher altitudes, like Colorado. This is to compensate for the thin air found at altitude. This can be done during installation by licensed gas professionals or the manufacturer at the time of purchase.
You will need to check the building codes of your city and state to determine if any restrictions apply and what size room is required to install a Ventless fireplace in your home.
ARE VENTLESS FIREPLACES SAFE?
Although they’re generally safe, ventless fireplaces do come with potential health hazards regarding the quality and quantity of oxygen inside the house.
Due to this many states have stringent regulations regarding installation and use, California notably being the strictest.
A built-in oxygen sensor (ODS), is required for vent-free appliances. This helps maintain the oxygen level above 18% (anything below that is considered unhealthy). If the level drops below 18% the ODS will shut off the gas flow to the fireplace.
To ensure sufficient oxygen in the room, Ventless gas fireplaces can only produce 40,000 BTUs an hour. (BTU = British Thermal Unit, a measure of heat output) The maximum BTU output for bathroom or bedroom installation is limited to 6,000-10,000 BTUs per hour.
Because combustion air can’t escape through chimneys, ventless gas fireplaces increase the odors in your home. A Ventless fireplace’s odor will be strongly affected by the use of perfume, air fresheners, and incense as well as pet dander and dust.
The lungs can be irritated by the exhaust from the fireplace. You should avoid installing a ventless gas fireplace if you have severe allergies or respiratory problems like chronic bronchitis or asthma.
You can purchase ventless gas fireplaces in all the same styles Direct Vent is available in. With Linear again being the most popular.
B-VENT GAS FIREPLACES
WHAT IS A B-VENT FIREPLACE?
B-Vent or Natural Vent gas fireplaces are less expensive than Direct Vent or Ventless. There are a couple of things that make these fireplaces the least popular option for most customers though. You will have limited options regarding the placement of the fireplace. Also, they are very inefficient, so the money you may have saved during the initial purchase will be going out of the chimney.
WHAT DOES A B-VENT FIREPLACE DO?
B-Vent fireplaces have an open front design. They work in the same way as wood-burning fireplaces. The fireplace draws fresh air from within the house to assist combustion and then uses a vertical vent to remove the by-products. Along with the by-products will go most of the heat that is being produced by the fire. So, think of B-VENT fireplaces as a decoration rather than a true heating source.
WHAT KIND OF VENTING DO I NEED?
B-Vent fireplaces are made of a double-walled, insulated tube or pipe. Just like a classic masonry chimney, the B-vent has to run straight up and down and end above the roof. Because of these requirements, the possible installation locations are limited.
ARE B-VENT FIREPLACES SAFE
Yes, they are very safe when used and maintained properly. Combustion by-products are expelled by vertical venting. This eliminates the possibility of dangerous gasses building up inside your home.