Patio heaters: are they really used to heat open spaces?

What would humanity be if it weren’t for its tireless desire to achieve the impossible. Among other things, we couldn’t fly on an airplane or cure serious illnesses, but surely the planet would be cleaner, with more rhinos and orangutans, and we wouldn’t have global warming.

In some utopias, like finding the philosopher’s stone or the submerged city of Atlantis, we’ve already given up, but in others, like heating an outdoor space in the dead of winter, we keep trying.

“It’s impossible”, begins by explaining María Luisa del Campo, director and academic of the technological center Kipus , from the University of Talca, where he specializes in energy efficiency. “In an open space, such as a patio, deck or balcony, as quickly as heat is generated, it is lost. Nearly 80% of the energy is supplied from the cold night air, so it is not recommended to heat an outdoor space.

Miguel Castro, professor of construction engineering at Duoc UC de Alameda, agrees with her. “Because there is a constant flow of air in an open space, almost all the heat produced goes away,” he says. “Therefore, having an outdoor stove is neither durable nor cheap.”

But as long as the spirit of Nicolás Massú lives on…”nothing is impossible, eh…, no eh… ”—, there will be no shortage of those who keep trying, again and again, to heat up the unheatable. For them, with these two experts, we will see which are the least inefficient and most reasonable alternatives among terrace stoves.

In this context, where no option is totally recommendable, the one that for Miguel Castro would be the most effective is the gas patio stove, for 11 and 15 kg bottles, which has the shape of a mushroom, with a sort of metal cap on top.

“Although their power and efficiency depend on the model and brand, these stoves or heaters generally use 800g of gas per hour or more, they have a heating radius of 3 meters and, thanks to this hat, the heat can be radiated more horizontally”, explains Professor Duoc UC.

“We must not forget, says the academic Del Campo, that the heat rises, so this plate they have on top – called a deflector, according to the manufacturers – is the one that manages to keep it at our level.”

The problem, she says, is that the only way to take advantage of that higher temperature in an open area, like a patio or deck, is to be very close to the stove. If you take a step or two, it’s as if the heating wasn’t there.

There are also pyramid-shaped models, “more efficient”, according to Miguel Castro, but also much more expensive: they can cost more than double the previous one. “Its advantage is that it has a tube that radiates heat throughout its elevation, which gives it more power.”

Castro also mentions biomass heaters, which use pellets as fuel. “The initial cost of the device is higher – its price usually varies between 350 and 500,000 pesos – but the consumption is lower: they have an approximate output of 1.8 kg per hour.”

In this article on indoor stoves, we have already mentioned how electrical appliances are inadvisable. They spend a lot of energy and generate little heat. We regret to tell you that to heat your balcony or your terrace they will not be of much use to you either.

“They have a very low radiation capacity and a very high consumption”, explains María Luisa del Campo. “Zero effective”. The same is true for Miguel Castro: “We have not yet reached the point where electrical appliances manage to generate enough heat with an appropriate energy expenditure. For the moment, these stoves heat less and consume as much or more than those of other fuels”.

That is to say: if an electric stove is not ideal for heating the interior of your house or your apartment, it will be even less so for the exterior.

But in the description of an electric patio heater, it is stated that its power is 1500 W, similar to that of a gas heater. Shouldn’t it get hot? No, Castro said. “Make no mistake: Wattage, which is measured in watts (W), is the amount of energy an appliance produces or consumes, as opposed to heat capacity, which is usually measured in BTUs (British thermal unit)”.

That is, the fact that they have the same power only guarantees the amount of energy they will consume, not the heat they will generate.

If, despite everything, you are still convinced to buy a terrace stove, María Luisa del Campo, from the University of Talca, suggests intervening in the space so that it is not so open, thus allowing the heat to remain in the place a little longer.

“A good strategy would be, like they do in bars or restaurants, to close with plastic curtains, for example, and create some insulation,” he says. “Only with this can you generate great change.”

“Instead of losing 80% of the heat,” adds Miguel Castro, “you’ll only be wasting ‘50%.’

Also take advantage of remembering that these stoves are designed for small spaces, not large patios or open plots. “Outdoors, none of these heaters work.” There, it would be more convenient to light a grill and uncork a bottle: it is much more possible that thus nobody is very cold.

*Prices for products in this item are updated as of July 20, 2023. Values ​​and availability are subject to change.