Not a fault
The heater works and the patio is still cold
This is the most common complaint in the category and the one least likely to be a fault. Four causes, none of them a broken heater, all of them fixable.
Almost always one of four things, and none is a fault: the heater is undersized for the area, the patio is too exposed and warmed air is being stripped away, the unit is in the wrong place, or its coverage circle does not fit the shape of the space.
First, rule out an actual fault
It takes ten seconds and it is worth doing before assuming anything.
- Gas unit: is the flame steady, blue at the pilot, and the main burner fully alight across its width? A partly lit burner or a yellow flame is a genuine fault and belongs on the fault tree page.
- Electric unit: is every element glowing? Multi-element quartz heaters can lose one and keep working at reduced output, which reads exactly like this complaint. Electric diagnostics.
- Gas unit, nearly empty cylinder: vapor pressure falls as a cylinder empties and cools, and output can drop noticeably at the end. Weigh it.
If all of that is fine, the heater is doing what it was built to do, and the problem is somewhere else. Here are the four candidates in order of likelihood.
Cause 1: it is undersized
Run the numbers before anything else. Area times 20 BTU per square foot for an open patio, adjusted for enclosure and exposure. If the answer exceeds the heater's rated output, you have your explanation and no amount of adjustment will fix it.
Work out your patio
How much heater does this patio need?
The answer
3,360 BTU/h
for 168 sq ft. That is 985 watts if you go electric, which one standard outlet can deliver.
The working
- 12 ft x 14 ft = 168 sq ft
- 168 sq ft x 20 BTU/sq ft = 3,360 BTU/h for an open patio in still air
- x 1 for “Open sky, no roof” = 3,360 BTU/h
- x 1 for average — some exposure = 3,360 BTU/h
Propane, per hour
$0.10
Electric, per hour
$0.18
20 lb cylinder lasts
128.3 h
The commonest version of this is a 1,500 W electric heater on an open patio. At 5,118 BTU/h that covers about 256 sq ft in still air with the beam pointed at you, and on an exposed patio far less. Electric heaters are excellent under a roof and outmatched in the open. The comparison.
Cause 2: the patio is too exposed
This is the one people never suspect and it is frequently the answer. A breeze does not reduce a heater's output — it removes the warmed air that output produced, continuously, and replaces it with cold air.
The tell is that it works on still evenings and disappoints on breezy ones, with no other difference. If that matches, nothing is wrong with the heater and a bigger one will not help much either. On our sizing model, exposure raises the requirement by about 55 percent relative to shelter, and a windbreak is the fix that changes the arithmetic rather than fighting it.
Cause 3: it is in the wrong place
Radiant heat is directional. A heater against a wall behind the seating warms the wall. A mounted infrared unit aimed at the middle of the patio warms the middle of the patio, where nobody is sitting.
- Mounted units: aim at the chairs. Seven to nine feet up, angled down at where people actually sit, not at the geometric center of the space.
- Towers: bring them closer. Warmth falls off with distance, so on a cold evening the answer is often to move the heater in rather than turn it up.
- Nothing in the way. A parasol, a tall planter or a chair back between the heater and a person blocks radiant heat completely. It is a line-of-sight medium.
- Move the chairs, not just the heater. Cheaper, faster, and it works.
Cause 4: the circle does not fit the space
A single heater covers a circle. Most patios are rectangles. On a long, narrow space one central heater leaves both ends cold even when the total output is more than sufficient, because the circle spills sideways onto the lawn and does not reach the corners.
The rule of thumb: if your seating area is more than about twice as long as it is wide, plan for two heaters regardless of what the BTU total says. Two smaller units placed along the length beat one large one in the middle every time. The geometry.
Quick picks
Ranked for fit, not for hype. Output is the maker’s published figure; reach is computed from it or from the maker’s own radius claim, and the table says which. Tap a row for the full write-up, or go straight to the listing.
| # | Product | Best for | Output | Reach | Price |
|---|---|---|---|---|---|
| 1 | GenericNo photo Clear vinyl curtainsThe highest-leverage purchase on this whole site. Blocking the wind on two sides changes the heat a patio needs by more than any heater upgrade does, and costs a fraction as much. | Turning open sides into walls | n/a | n/a | Check price on Amazon |
| 2 | Dr. Infrared HeaterNo photo Dr Infrared 1500 WRadiant heat that a breeze cannot blow out, on a plug. 1,500 W is only 5,118 BTU/h, which sounds like nothing next to a propane tower and lands far more of itself on you. | Wind, and anywhere with a roof | 1,500 W | 256 sq ft | Check price on Amazon |
| 3 | Amazon BasicsNo photo Amazon Basics 46kOne of the very few towers whose maker publishes a coverage radius rather than a vague area, and the 9 ft figure survives the arithmetic. That alone puts it ahead of most of the field. | The published-radius honesty test | 46,000 BTU | 254 sq ft claimed | Check price on Amazon |
Reach marked “claimed” is the maker’s own published figure. Reach without that label is ours, computed from published output at 20 BTU per square foot for an open patio. Neither is a measurement we took.
Top pick · Turning open sides into walls
Clear Vinyl Patio Enclosure Curtains, 23 oz, with Grommets
The highest-leverage purchase on this whole site. Blocking the wind on two sides changes the heat a patio needs by more than any heater upgrade does, and costs a fraction as much.
- Fuel
- Accessory
- Output
- Not published
- Reach (computed)
- Not published
- Cost per hour
- n/a
What works
- On our own sizing model, moving a patio from exposed to sheltered cuts the required output by about a third — that is a bigger change than any heater swap
- Clear vinyl keeps the view, which is why people actually leave it up rather than taking it down after a week
- Grommets every 12 inches make it a rope-and-tie job, not a construction project
What does not
- Enclosing a patio changes the heater rules. Once you have walls and a roof, an open-flame propane unit is no longer appropriate — read the safety page before you buy both
- Vinyl goes cloudy and stiff with age and UV, faster in hot climates
- It flogs and cracks in real wind unless it is tied at every grommet, not just the corners
| Published specification | |
|---|---|
| Material | 23 oz clear PVC vinyl tarpaulin |
| Fixing | Metal grommets, ropes and ties included |
| Claimed properties | Waterproof, anti-UV, tear resistant per the listing |
| Intended use | Porch, pergola, gazebo, balcony |
| Maker’s coverage claim | None published — the reach figure above is ours |
| Safety listing | Not applicable — this is a fabric panel, not an appliance |
Who it is for
Any patio where wind is the actual problem and the heater is being blamed for it.
What it is not for
Sealing a space fully. A partly open, well-ventilated enclosure is the goal; an airtight one with a combustion heater inside is dangerous.
Sources for this entry
2 · Wind, and anywhere with a roof
Dr Infrared Heater Carbon Infrared Patio Heater, 120 V / 1500 W
Radiant heat that a breeze cannot blow out, on a plug. 1,500 W is only 5,118 BTU/h, which sounds like nothing next to a propane tower and lands far more of itself on you.
- Fuel
- Electric
- Output
- 1,500 W = 5,118 BTU/h
- Reach (computed)
- 256 sq ft · 9.0 ft radius
- Cost per hour
- $0.28
What works
- Infrared warms objects, not air, so it is the only heat that survives a breeze — this is the single reason wind changes the whole buying decision
- No combustion means no flue gas, which is what makes it legal and sensible on a screened porch where propane is not
- Three settings matter more than they sound: 900 W costs a third less to run and is enough most evenings
What does not
- 1,500 W is 1,500 W. Nothing at this wattage heats faster than anything else at this wattage; the differences between electric heaters are beam shape and build, not power
- It heats what it points at. Step out of the beam and you are cold immediately — this is a fundamentally different experience from a tower
- A 120 V plug-in unit is capped by your circuit, not by the maker. See why 1,500 W is the ceiling
| Published specification | |
|---|---|
| Rated power | 1,500 W at 120 V |
| Settings | 900 W / 1,200 W / 1,500 W |
| Element | Carbon infrared lamp |
| Reflector | Mirror aluminum, 90% reflectivity per the maker |
| Housing | Anodized aluminum, rated for outdoor use |
| Mounting | Wall and ceiling brackets plus remote in the box |
| Maker’s coverage claim | None published — the reach figure above is ours |
| Safety listing | ETL listed, per the maker's published product data |
Who it is for
A covered patio, pergola or screened porch where you can mount it overhead and point it at where people sit, and anywhere wind ruins a flame.
What it is not for
A big open patio with nowhere to mount it. Radiant heat needs a line of sight and a place to hang from.
3 · The published-radius honesty test
Amazon Basics 46,000 BTU Outdoor Propane Patio Heater
One of the very few towers whose maker publishes a coverage radius rather than a vague area, and the 9 ft figure survives the arithmetic. That alone puts it ahead of most of the field.
- Fuel
- Propane
- Output
- 46,000 BTU/h
- Reach (claimed)
- 254 sq ft · 9.0 ft radius
- Cost per hour
- $1.35
What works
- A published 9 ft radius is a 254 sq ft circle, and 46,000 BTU is far more than that area needs — a claim on the conservative side of its own specification, which is rare here
- The water-fill base box is a real anti-tip measure, not a sticker: filled, it is the difference between a windy evening and a repair bill
- One-touch ignition and a chain for the cylinder are both small things the cheap clones drop
What does not
- The listing does not name a safety certifying body, only the tilt valve, so we cannot tell you it is CSA listed
- 91 in tall with an open flame: the same wind exposure as every other tower of this shape
- The water box has to be emptied before a freeze or it splits
| Published specification | |
|---|---|
| Rated input | 46,000 BTU/h |
| Published reach | 9 ft radius |
| Dimensions | 32.1" L x 32.1" W x 91.3" H |
| Fuel | 20 lb propane cylinder, not included |
| Safety | Tilt auto-shutoff valve; chain to secure the cylinder |
| Base | Water-fill box for ballast, wheel kit included |
| Maker’s coverage claim | 9.0 ft radius, which is 254 sq ft |
| Safety listing | Tilt auto-shutoff valve; the listing does not name a certifying body |
Who it is for
An open patio where you want the largest honest circle of warmth per dollar and are happy to handle cylinders.
What it is not for
Anywhere enclosed, and anywhere the base cannot be filled with water — an empty ballast box makes this a tall, light, tippy object.
Sources for this entry
What to do, in order of cost
- Move the chairs closer. Free, immediate, and it resolves a surprising share of these cases.
- Reposition the heater. Also free. Closer, higher, aimed at people rather than at the space.
- Block the wind on one side. A windbreak cuts the requirement by about a third, permanently, for a fraction of a heater's price.
- Add a second heater rather than a bigger one. Better coverage on a rectangular space, and it gives you two zones you can run independently.
- Replace it, if the sizing arithmetic says it was never going to work. Only after the first four — replacing an undersized heater with a slightly less undersized one is the expensive version of this mistake.
The honest summary
In the large majority of these cases the heater is fine and the patio is the problem. Working out which of the four causes applies takes about five minutes with a tape measure and the calculator, and it will usually point at a fix that costs less than a new heater.
Common questions
Why does my patio heater not put out much heat?
Usually one of four things, none of them a fault: it is undersized for the area, the patio is exposed and warmed air is being stripped away, it is positioned or aimed badly, or its coverage circle does not fit a long narrow space. Check the flame or elements first, then work through those.
Is my patio heater faulty if the patio is still cold?
Probably not. Check that a gas burner is fully alight and blue at the pilot, and that every element on an electric unit is glowing. If those are fine, the heater is working and the cause is sizing, exposure, placement or shape.
Will a bigger patio heater fix a cold patio?
Only if the problem is genuinely output. If the patio is exposed, a bigger heater loses its extra output to the same wind. Blocking the wind cuts the requirement by about a third and costs far less than upgrading.
How close should you sit to a patio heater?
Closer than most people do. Radiant warmth falls off quickly with distance, so on a cold evening moving the chairs in a few feet does more than turning the heater up — and it costs nothing. Observe the published side clearance of 24 to 36 inches for gas units.
Read next
Patio heater BTU calculator
Your patio's BTU requirement with every multiplication shown, plus why the published rules disagree.
Patio windbreaks, and why they beat a bigger heater
Vinyl, mesh and curtains compared, with what enclosing a patio changes about your heater choice.
Patio heater coverage area
Radius to area, why the two get confused, and how to sanity-check any coverage claim.
Patio heater will not stay lit
The ordered diagnostic for a heater that lights and dies, ending in the part that fixes it.
Electric vs propane patio heaters
Output, cost, coverage, wind and installation compared, with the arithmetic and picks for both answers.