Every propane heater is rated by how much heat it makes, in BTU per hour. What your guest feels is a different number: how much of that heat actually reaches them. The EMBER Patio Heater is a self-powered, forced-air propane heater built to close that gap, with a fan that runs on the heater's own flame.
This post walks through the engineering: how heat moves outdoors, how a flame can power its own fan, and what keeps the whole system safe.
How heat moves on an open patio
Heat travels three ways: conduction through solids, radiation in straight lines, and convection carried by moving air. Outdoors, the last two decide whether a guest is warm.
Hot air rises. Air heated by a burner is less dense than the air around it, so it floats upward in a plume. On an open patio nothing stops that plume. A heater that leaves its warm air alone is heating the space above everyone's heads.
Radiant heat needs a line of sight. A mushroom heater glows at the top of a tall post and radiates outward and down. Radiant warmth weakens with distance and stops at whatever is in the way: a table, an umbrella, another guest. Meanwhile, its combustion gases still rise straight up.
Moving air transfers heat faster. This is the part forced air uses. The rate heat moves between air and a surface follows Newton's law of cooling:
q = h × A × (Tair − Tsurface)
Here h is the heat transfer coefficient, A is the surface area, and the last term is the temperature difference. Textbook values of h for air run roughly 2 to 25 W/m²·K when the air is still and 25 to 250 W/m²·K when it is moving. Wind chill is this effect working against you. A stream of warm air is the same effect working for you.
That is why the EMBER does not rely on radiation alone. A fan drives warm air outward and down toward people, instead of straight up the way a mushroom heater does. The EMBER is rated from 4,000 to 18,000 BTU per hour; the fan decides where that heat goes.
Where the fan's power comes from
Most forced-air heaters need an outlet to run the fan. The EMBER's fan runs off the flame itself: a built-in thermoelectric generator turns the heat into the electricity that powers it. The physics behind it is two centuries old.
The Seebeck effect. In 1821, Thomas Johann Seebeck found that a temperature difference across a junction of two different conductors produces a voltage. Heat drives charge carriers from the hot side toward the cold side, and that flow becomes a current when a circuit is closed. For one junction, the voltage is proportional to the temperature difference:
V = S × ΔT
S is the Seebeck coefficient of the materials and ΔT is the difference between the hot and cold sides. A thermoelectric module wires many small semiconductor pairs in series, so their voltages add, while heat flows through all of them side by side.
Power grows with the square of ΔT. Delivered into a matched load, where R is the module's internal resistance, a module's power is:
P = (S × ΔT)² ÷ 4R
Double the temperature difference and the available power roughly quadruples. That is why a thermoelectric generator does its best work next to a flame, with a cooler side close by.
No moving parts. A thermoelectric generator has no turbine, piston or brushes. The same principle powers the radioisotope generators on deep-space probes such as Voyager 1 and 2, where the heat comes from radioactive decay instead of a flame.
On the EMBER, that generated power runs the fan and a built-in 5V USB port. The fan needs no batteries: there is no cord and no outlet. Once lit, the fan starts on its own within about 30 seconds. That short wait is the physics at work: the generator makes power only after a temperature difference builds across it.
The closed loop
The EMBER's heat and its fan power come from the same flame. Burn rate sets the heat; the heat sets the generator's output; that output sets the fan speed.
Because power grows with the temperature difference, the system tracks itself. Turn the knob up and the fan speeds up with it, with no separate switch to flip.
Ignition, fuel and runtime
Pulse ignition lights the EMBER at the push of a button. Push the control knob in, turn it to Pilot, and an included AA battery fires a steady train of sparks until the pilot catches. No matches, no lighter.
One knob then steps through three gas settings. The fan follows on its own, at a speed matched to the setting. The fan boost button raises airflow to its maximum without changing the burner's BTU output or fuel use.
The EMBER runs on propane only: two 1 lb cylinders inside the unit, or a 20 lb tank through a 6-foot stainless adaptor hose. On the EMBER Patio Heater, the 20 lb tank is concealed in the stand.
| Setting | Input (BTU/h) | Two 1 lb cylinders | One 20 lb tank |
|---|---|---|---|
| Low | 4,000 | about 10 hours | about 100 hours |
| Medium | 9,000 | about 5 hours | about 50 hours |
| High | 18,000 | about 2.5 hours | about 24 hours |
These runtimes are simple fuel math. Propane holds roughly 21,600 BTU per pound, so runtime is stored energy divided by burn rate:
t = (20 lb × 21,600 BTU/lb) ÷ 18,000 BTU/h ≈ 24 hours
Actual runtime varies with ambient temperature and altitude.
Safety and certification
The EMBER is CSA certified to U.S. standards for indoor and outdoor use. CSA Group tested and certified it to ANSI Z21.103-2017. Four automatic shutoffs watch the conditions that matter most in a gas heater.
| Safeguard | What it watches | What it does |
|---|---|---|
| Oxygen depletion sensor (ODS) | Oxygen level around the heater | Shuts the heater off if oxygen drops too low |
| Tip-over switch | The heater's orientation | Cuts the flame if the unit is knocked over |
| Thermal cutoff | Internal temperature | Shuts the heater down if it overheats |
| Flame-out shutdown | Whether the flame is lit | Stops the fuel supply if the flame goes out |
How an ODS works, in general. An oxygen depletion sensor pairs a precisely tuned pilot flame with a thermocouple. When oxygen falls, the flame lifts away from the thermocouple, the thermocouple cools, and the gas valve closes. No electronics are needed; the physics of the flame is the sensor.
The flame sits behind glass. Fireplace glass separates guests from the blue propane flame. It removes the open flame and keeps a breeze from blowing the flame out.
Cool surfaces by design. Fresh air circulates through gaps in the frame, keeping the top, sides, back and bottom cool to the touch. The front, where the warmth is meant to go, is the hot zone.
Indoors, follow the included ventilation and operating guidance, as with any fuel-burning appliance.
What the engineering means on a working patio
- Aim it at the seats. Forced air is directional. Face the front of the heater toward the tables you want warm, not toward a walkway.
- No cords across the floor. The fan makes its own power, so there is no extension cord for staff or guests to trip over.
- Fewer tank swaps. About 24 hours on a 20 lb tank on high covers several services between changes.
- Move it with the crowd. The EMBER Patio Heater rolls on four locking casters. The head lifts off the stand to carry, and works on its own as the EMBER Portable.
- One unit, inside or out. The EMBER is CSA certified to U.S. standards for indoor and outdoor use, so the same heater can serve a patio, an entry or a private-event room.
It's not the heat you make. It's the heat you feel.
FAQ
Is the EMBER electric?
No. It burns propane. Its fan runs on power from a thermoelectric generator that runs off the flame.
Does it need batteries?
The fan does not. An included AA battery powers the pulse igniter.
Why does the fan take a moment to start?
The generator needs a temperature difference across it before it makes power. The fan starts on its own within about 30 seconds of lighting.
Does the fan boost button use more propane?
No. It raises airflow without changing the burner's BTU output or fuel use.
See the EMBER on your patio
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