Patio heaters extend the usable season of decks, balconies, and covered porches by delivering on-demand warmth without the smoke and cleanup of a wood fire. Shoppers who compare models by price alone often miss the factors that determine whether a heater actually performs: fuel type, heat output, coverage area, and stability. The decision process is the same one builders walk through when choosing outdoor heating for a client, so the comparison points in this article apply whether you are outfitting a residential patio or specifying equipment for a commercial terrace. Start with the basics of how these heaters work, then work through fuel options and sizing before you spend. For a fuller treatment of the same decision, see the breakdown of outdoor patio heater types, fuel options, and selection tips.
How Outdoor Patio Heaters Produce Heat
All patio heaters convert fuel or electricity into radiant energy that warms people and surfaces directly, rather than heating all the air in an open space. Radiant heat behaves differently from the forced-air heat used indoors, which matters when you position the unit. Electric models pass current through metal or quartz elements that glow and emit infrared energy; gas models burn propane or natural gas against a mesh screen that radiates heat outward. The on-demand nature of both types resembles the way an instantaneous water heater produces hot water only when a tap opens, and the comparison is useful when you evaluate efficiency: neither system stores energy, so standby losses stay near zero.
Radiant Heat and Convective Heat
Radiant heaters warm whatever is in their line of sight: skin, clothing, furniture, and the paving beneath them. Objects absorb that energy and release it slowly, which is why you feel heat on your face while the air around you stays cool. Convective models, usually fan-driven electric units, push warm air across a wider area but lose effectiveness in wind because moving air carries the warmth away. For a wind-sheltered corner, either type works; for an exposed deck, radiant output wins.
Heat Output Ratings
Manufacturers rate gas heaters in British thermal units per hour (BTU/h) and electric heaters in watts, and the two scales convert directly: 1 watt equals about 3.41 BTU/h. A 1,500-watt electric unit delivers roughly 5,100 BTU/h, while a typical propane patio heater produces 40,000 to 46,000 BTU/h. That gap explains why gas models throw heat over larger areas, and why electric units suit small balconies and dining nooks where 150 to 200 square feet of coverage is enough.
Propane, Natural Gas, and Electric Fuel Options
Fuel choice drives purchase price, operating cost, and installation complexity, and it is the first decision to lock down. Propane units are portable, run on refillable 20-pound tanks, and need no wiring, which makes them the default for renters and for homeowners who want to move the heater around. Natural gas models connect to the home supply line, eliminate tank refills, and cost less per hour of use, but they require a licensed contractor to run gas piping and a permanent location. Electric heaters are the cheapest to buy, silent, and free of combustion byproducts, yet their lower output limits them to small spaces. Independent reviews of the best patio heaters on the market consistently rank these three categories in that order for flexibility, convenience, and ease of installation, so match the priority to your situation.
Comparing Fuel Types at a Glance
| Fuel type | Typical output | Best for | Main trade-off |
|---|---|---|---|
| Propane | 40,000-46,000 BTU/h | Portable use on decks and patios | Tank refills and storage |
| Natural gas | 30,000-60,000 BTU/h | Permanent installations | Requires gas line and permit |
| Electric | 1,000-5,600 BTU/h | Small balconies and covered patios | Limited coverage area |
Output ranges overlap, especially at the high end of electric and the low end of gas, but the practical difference shows up in coverage. A 40,000 BTU/h propane unit comfortably heats a 200-square-foot dining area, while a 1,500-watt electric unit covers a table for four.
Mobility, Installation, and Permits
Portability follows fuel: propane and electric units can move with you, while natural gas units anchor to a fixed supply point. Before choosing natural gas, confirm local code requirements for gas piping, shutoff valves, and clearances, since an unpermitted connection can void insurance coverage. Electric units need a grounded outdoor receptacle, preferably on a dedicated circuit, because a 1,500-watt load draws 12.5 amps at 120 volts and leaves little headroom on a shared circuit.
Permit and Inspection Checklist
- Confirm whether a permit is required for the gas line or electrical circuit.
- Schedule inspections before the piping or wiring is concealed.
- Keep the manufacturer installation sheet on site for the inspector.
- Verify the shutoff valve is reachable and labeled.
Sizing Heat Output to Your Space
Heat output should match the square footage you actually occupy, not the whole yard. A common rule of thumb is 30 to 50 BTU/h per square foot of heated area in calm conditions, with the higher end for spaces open to wind or with high ceilings. Divide the patio into zones: a dining table needs a concentrated source overhead or beside it, while a seating group spreads warmth across a wider radius. The same logic applies indoors when tankless water heaters serve space-heating applications, where output must be sized to the room rather than the number of fixtures.
A Simple BTU Calculation
- Measure the length and width of the area you want to heat and multiply for square footage.
- Multiply that figure by 30 for sheltered spaces or 50 for exposed areas.
- Divide the result by the heater rated output in BTU/h to find how many units you need.
- Round up for windy sites and for spaces taller than 10 feet.
Example: A 12 by 14 Foot Patio
A 12 by 14 foot patio covers 168 square feet. At 40 BTU/h per square foot, the target is about 6,700 BTU/h, which a single 40,000 BTU/h propane heater exceeds comfortably; at 50 BTU/h, the target rises to 8,400 BTU/h and a mid-size gas unit still covers it. The same patio with two 1,500-watt electric heaters reaches roughly 10,200 BTU/h combined, enough for sheltered evenings.
Adjusting for Wind and Ceiling Height
Wind is the biggest enemy of outdoor heat because moving air strips warmth from skin and carries convective heat away. Orient the heater so the radiating face points at the seating area, and position it upwind of guests where possible. Under a covered porch, mount units at 7 to 9 feet above the floor and angle them slightly downward; higher mounting spreads heat thinner, and lower mounting creates hot spots.
Placement, Clearance, and Stability
Stability matters more than mobility: a tipped heater can start a fire or spill propane, so the base and the surface it sits on deserve as much attention as the burner. Manufacturers specify minimum clearances from combustible materials, and those distances are not suggestions. The same discipline that governs electric water heaters, where dual-element controls stagger heating loads to protect the wiring, applies to patio heater placement: keep clearances, watch the circuit, and never improvise.
Clearance Rules to Follow
- Keep at least 24 inches between the heater and any combustible wall, railing, or overhang, and 36 inches for units rated above 50,000 BTU/h.
- Maintain at least 10 feet of clearance between a gas heater and any propane tank not connected to it.
- Never place a heater under a low umbrella or canvas canopy; radiant heat can scorch fabric.
- Set the unit on a level, noncombustible surface such as concrete, stone, or composite decking rated for heat.
Stability and Wind Protection
Look for wide bases, weighted feet, and low centers of gravity. Units with wheels are convenient but should lock firmly before use. On windy days, move freestanding heaters to a sheltered corner or lower their output rather than letting the wind rock them. Hanging electric models avoid tip-over risk entirely and suit covered patios where a ceiling mount is available.
Maintenance, Storage, and Running Costs
A patio heater that runs season after season gets the same basic care as commercial water heaters, where selection, installation, and efficiency standards are written down precisely because downtime is expensive. Apply that mindset at home: keep the burner and reflector clean, inspect the gas hose for cracks, and store the unit before winter weather arrives.
Seasonal Maintenance Checklist
- Wipe the reflector and emitter screen monthly during heavy use to keep output at rated levels.
- Check the gas hose and regulator connections with soapy water for leaks before each season.
- Clean burner ports with a soft brush if flames turn yellow or uneven.
- Cover or store electric units indoors during rain and snow; moisture damages elements and switches.
Estimating the Cost Per Hour
Operating cost depends on local fuel prices. A 40,000 BTU/h propane heater burns about 1 pound of propane per hour, roughly 0.9 gallons, so at $4 per gallon the cost lands near $3.60 per hour. Natural gas at $1.50 per therm delivers the same output for about $0.60 per hour, and a 1,500-watt electric unit at $0.15 per kWh costs about $0.23 per hour. The electric unit is cheapest to run but heats the least area, so compare cost per square foot heated rather than cost per hour alone.
If the project is really about heating an attached sunroom, a screened porch, or a tight superinsulated home rather than an open patio, a radiant heater may not be the best tool. Thermal-mass systems such as masonry heaters store heat in heavy material and release it slowly, which suits enclosed spaces where the warmth can accumulate. Match the technology to the enclosure, and the heater you choose will earn its keep for years.