Space Heaters Gas |

Space Heaters Gas


Natural gas space heaters are often used to supplement central heating systems in areas such as added-on rooms, basements and garages.

Categorization of the heaters can be made according to:

  • Vented or Non-vented
  • Radiant or Convection
  • Power or Passive

Most utility companies do not endorse non-vented gas heaters for interior living spaces, and in some cases, they are against local codes. Before installing any space heater, the application and local codes (personal safety) must be considered.


Most natural gas space heaters have standing pilots that may be lit using spark igniters. The pilot also includes a safety that will not allow the main gas valve to the burner to open unless the pilot is first burning.  If the unit is radiant of passive conductive (no fan) no electricity is required to operate the unit. Larger units tend to be fan-forced heat and therefore must also be plugged into electricity for operation. Some units are equipped with an oxygen sensor that automatically shuts the unit off if O2 drops in the space – before carbon monoxide (CO2) can form. This is an important safety feature.

Larger, more expensive units will have remote thermostats; most have only a built-in adjustable dial setting, or simply an on-off setting.

Sizes range from about 5,000 BTUs/hour up to about 50,000 BTUs/hour.


Available Types


Radiant Surface

This type of heater fires either behind, in or on the surface of a ceramic radiant panel. The ceramic glows hot producing a source of heat that is ‘line of sight’ of panel. Convection heat is also produced off the top of the unit.

This type of heater is available from about 5,000 BTUs through about 20,000 BTUs/hour

The smaller heaters are non-vented (picture to right). Larger units may be vented.






Open Flame/Direct Heat

The open flame uses a burner that is open or behind glass to produce mostly convection heat out the top of the unit. A smaller amount of heat is given off the front in a line of sight from the flame.

These units are available in sizes from about 10,000 to 50,000 BTUs/hour. The smaller units are mostly non-vented; larger units may be direct-vented through the wall they are mounted on.
SpaceHtr_DirectVentConcealed Flame Direct Vent

Heaters with a concealed flame and direct vent of products of combustion burn the gas inside of a heat-exchanger. This system is the most often approved unit for codes and utility companies. They may also include an automatic pilot and circulation fan, which means they must be plugged into electricity. They must also be located on an outside, above grade wall.

These units tend to be a little larger and range in size from about 20,000 BTUs to 50,000 BTUs.
SpaceHtr_WallUnitWall Furnace

The wall heater design is the most like a furnace. They are often used in small apartments and condos. They use heat exchangers and are vented and approved by most codes and utilities. Some units can be equipped with ducts through the rear to heat more than one room. They may have auto-ignition pilots, remote thermostats, and be vented in a variety of ways, including up, so they could be used in a basement.

These are the largest units, available in sizes from about 25,000 to 75,000 BTUs/hour.




More Information

See also PTAC – Packaged Terminal Air Conditioners



Empire Comfort Systems
ECS, Inc.
918 Freeburg Avenue
Belleville, IL 62222-0529
Telephone: 618-233-7420 or 800-851-3153

Go to the Empire web site at


Source: Text Bob Fegan 12/2008; radiant heater pictures Empire web site; 7/2003; Rev 11/2005;

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