| 1. Radiant
Heat 101
Radiant heat is transfered directly from warm
objects to colder objects through invisible wavelengths
of energy (infra-red waves). It is easy to imagine how
radiant heat works when you think about standing in front
of a campfire. In the case of a radiant stove, the outer
surfaces of the stove get hot and transfer that heat to
other objects in the room - furniture, people, walls, ceilings,
etc. The end result is that same soul-satisfying feeling
of warmth that only comes from radiant heat.
Both our wood
stoves and our gas stoves burn fuel and generate heat inside
a firebox. The soapstone that surrounds the firebox absorbs
the heat and radiates it outward to objects in the living
space. Soapstone has a very high specific heat (or heat
capacity per pound of material). The soapstone slowly releases
heat and re-charges itself from the fire in a fairly even
and continuous cycle.
While the radiant heat from our gas
stoves feels very much like the heat from our woodstoves,
there are a few substantial differences. In a wood stove,
the fuel, wood, has to be loaded and re-loaded by hand.
A wood fire has a natural cycle - from start up to a period
of high burn, fading out to a gradual bed of coals and
ash. In a gas stove, the fuel is delivered automatically
to the stove and the burn rate is much more constant. The
maximum heat output of a woodstove is much greater than
that of a gas stove but the overall heat output over a
twenty-four period is actually about the same. The output
of a gas stove stays relatively constant over a given period
of time, enabling it to heat the same size space as a wood
stove.
The automatic delivery of fuel to the firebox opens
up a world of possibilities that don’t exist for woodstoves.
A gas stove can be connected to a thermostat that can regulate
the amount of heat produced through the use of temperature
settings, or timers, or both!
2. How It Works When the Power
Goes Out
The gas used in the stove is delivered under pressure.
If you have natural gas, the amount of pressure is controlled
by your utility company at the source. If you have propane,
the tank itself is pressurized and controlled by a regulator
located in the piping between the tank and your home. It
is adjusted for your particular appliance by another regulator
in the appliance itself. No pumps or other electrical devices
are necessary, which is why a gas stove can operate without
electrical power.
The wall thermostat and remote control
actually do require some electrical power, but such a small
amount that it can be generated by household batteries.
Aside from the thermostat, the controller in the stove
generates its own millivoltage from the pilot flame itself,
and operates the valves to the pilot and main burner, shutting
them off in the event that the pilot goes out.
3. Direct
Vent For Safety & Indoor Air Quality
The flue for direct vent stoves
is made up of concentric pipes. The inner pipe carries
hot flue gasses outside. The outer ring draws fresh air
from the outdoors into the stove for combustion.
As the
hot exhaust and the cold outside air pass by each other,
the incoming air is warmed and the outgoing exhaust is
cooled. This heat exchange is the reason that direct vent
gas stoves do not need chimneys. A direct vent gas stove
can be vented directly through an outside wall. See our
article “Direct Vent System” for
complete details about planning and installing a direct vent
system.
4. Meet the Controls
Several components work together
in a gas stove to make up a safe, efficient system that
is simple to operate. First we’ll give you an overview of how
the system works, then we’ll break down the components for
you.
Gas stoves rely on a valve to control the flow of natural
gas or propane into the stove. In our stoves, there are
two ports for the gas. One port leads to a pilot light.
The other leads to the main burner. The pilot is lit by
a piezo ignitor and must be on for the main burner to turn
on. The pilot flame heats up a thermocouple and a thermopile
(two important safety features of your gas stove). As long
as the pilot is lit, the main burner can be turned off
or on as needed and the flame height can be adjusted. As
the gas burns in the main burner, the flames rise up through
a ceramic log set to create the look of a real wood fire.
The flames create the heat that is radiated out from the
firebox and absorbed by the soapstone. The air that’s required for combustion
is drawn in through a direct vent system that also exhausts
flue gases at the same time.
Now let’s look at each of the
components one by one to get an idea of how the system works.
A complete step-by-step guide to stove operation can be found
in the Owner’s Manual that is included with every new stove.
Piezo: This is an igniter that lights the pilot by creating
a spark. It is the same type of lighter that’s found on home
barbecue grills. A match or flame is not required to light
the pilot.
High-Low Knob: A knob to adjust the flame height
and heat output from High (100% power) down to Low (70%).
Gas Control Knob: A knob that controls gas flow to the
pilot and the main burner. It is turned to the “pilot” position
to light the pilot, and then turned the rest of the way to
the “on” position to allow flow of gas to the main burner.
The main burner can be operated manually by simply pressing
an“On-Off” rocker switch, or automatically, by means of
a pre-set thermostat.
On-Off Switch: A toggle switch that
will allow (or interrupt) the flow of gas to the main burner.
When turned “off”, the pilot will remain lit and the burner
will go out.
Main Burner (or Burner Pan): A stainless steel
pan located under the log set where the gas and air are
mixed and ignited. Flames rise up through the log set that
sits on top of the Main Burner.
Pilot: A small flame that burns
continuously once lit. The pilot must be lit for the stove
to operate.
Thermocouple and Thermopile: Small bi-metal devices
that produce DC voltage when heated by the pilot. While
the pilot is on, low voltage activates an electromagnet
which keeps the gas supply valve open. Should the pilot
go out, the supply of gas to the stove is shut off — an important
safety feature.
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