Like oil heaters, gas heaters may be flued or flueless and may heat by convection or radiation. They provide the advantage of quickly heating an area, but unflued heaters also contribute to moisture in the air. Gas heaters operate at about 75% efficiency for flued models and about 90% in flueless.
Town gas or natural gas is piped to the house
by the local gas company; no storage space is
required and it is cheap and clean. It is lighter
than air, but because of its flammability can
constitute a fire or explosion hazard.
Pressure at the point of use can vary
depending on a number of factors, for
example, pressure at source or demand by others at the same time.
It is ideal for quick local heat for a small area and for heating the body directly. Ultimately the room air would acquire heat from objects in the room that have been heated.