Patio heater guide – gas, infrared or bioethanol, which is right for you?

Outdoor heaters are powered by one of three different energy sources: gas, electricity, or bioethanol, each of which has advantages and disadvantages. Our guide will help you decide which is best for you.

Should we even use outdoor heaters?

Before we start, it’s important to admit that outdoor heating is generally very inefficient: without a building to contain the heat, much of the warmth generated just dissipates into the night air. This is particularly true for gas heaters and wood firepits, which rely on convection, and less so for electric heaters, which radiate heat. Outdoor heaters generally don’t have a great range; you need to sit close to them to feel the benefit. Poorly made models don’t stand up to the elements very well. Then there’s the problem that many patio heaters run on propane, a fossil fuel that generates carbon dioxide as it burns, while firepits generate both carbon dioxide and smoke.

Beyond all this, most outdoor heating is, strictly speaking, unnecessary: you could, after all, just pack up and go indoors when it starts to get cold. That said, if you can’t resist the seductive appeal of gathering around a cosy flame, it is useful to know which are the better and worse choices for your pocket and for the environment. It also makes sense to take some simple steps to minimise the amount of outdoor heating that you need, by:

• having outdoor lighting, which tricks the brain into making us feel warmer
• using blankets and other textiles like throws and cushions to keep warm
• putting on an extra layer of clothing
• building a shelter or windbreak to create a warm nook protected from the wind

Gas patio heaters

Gas patio heaters come in the freestanding mushroom, pyramid and column shapes we’re familiar with from pub gardens and restaurant terraces, and as minimalist firepits and fire tables, where the flames emerge from lava rocks or fake logs. Running on cylinders of propane gas, they offer the primal appeal of real flames, with full controllability at the turn of a knob. But gas heaters involve ongoing work: you have to change empty gas cannisters and go get refills. Plus, as a fossil fuel, propane is a far from sustainable choice.

Design

Freestanding, table-top, firepit and firetable models are available, made from steel, stainless steel, glass reinforced concrete or the cheaper lookalike magnesium oxide. On smaller models there is often not room to store the gas bottle inside the heater. In this case, it will need to be hidden away somewhere nearby and attached to the unit via a long hose – you can get purpose-made cannister covers to disguise them.

Upright patio heaters hold the gas canister in their base, which makes them quite bulky and heavy – but also quite stable. They can be moved around relatively easily when not in use and placed on pretty much any stable surface because they don’t, of course, need connecting to the mains (although some high-end firepit-style heaters can be connected to the mains gas supply if they are going to be fixed permanently in a sheltered outside space). Gas heaters can be used on decking and under shelter, provided you follow the manufacturer’s guidance about clearance height above the heater.

Gas heaters are rated according to their heat output, in BTUs (British Thermal Units) or Watts, and the area they will heat in m2, or how far the heat will reach, in metres. Stainless steel and aluminium models are better at resisting rust, and concrete will last longer than magnesium oxide.

Maintenance

Some patio heaters need to be assembled out of the box. They all run on propane or patio gas. Patio gas is just propane in a green bottle – usually propane bottles are red. The main difference between the two lies in the regulators: patio-gas cylinders are compatible with clip-on gas regulators and propane with a screw-in regulators. Calor has some useful information on its website about how to connect gas bottles and which type to buy. Always use a cover on your heater, and take it indoors for the wettest part of the year.

Sustainability

There’s no getting away from the fact that propane is a fossil fuel that generates carbon dioxide as it burns, and gas heaters are also quite inefficient. They can be reasonably good at heating large outdoor areas, but because they heat by means of convection, they waste a lot of energy as they do this, heating air that just rises up into the sky.

Running costs

Gas heaters are expensive to run, so they are best suited to occasional use. A 13kg propane cylinder will cost about £120 to buy the first time and then £45-50 for each refill. Patio gas costs a very similar amount for the first bottle and slightly more for each refill. The precise cost of running your heater depends on whether you use it on full power. But a medium-sized heater that will run for ten hours on full power off a 5kg patio-gas cylinder – about £35 to refill – costs £3.50 an hour. Larger heaters will cost more: Which? recently found that it costs about £6-£8 an hour to run a gas patio heater.

Safety

Gas heaters are a safety hazard for children and animals, who should always be supervised when the heaters are on. Gas heaters must be used in a well ventilated space, and at a safe distance from anything flammable. Make sure freestanding models have a safety cut-off in case of them getting tipped over. Don’t move heaters while they are on. Firepit and firetable models often come with a clear glass wind-guard, which also acts as a safety device.

Tracey Thompson, of Ecodek decking says, “Propane and gas options are much better for use on composite decking [than firepits] as they create less heat and don’t create embers, so they’re less likely to cause damage. Electric firepits are also a great option as they are more controllable temperature-wise.”

Electric patio heaters

Joanna Humphreys from Direct Stoves says, “While electric patio heaters offer more function than they do form, they can be more discreet. Although not as attractive, they produce radiant heat, and the infrared heat allows customers to point in their desired direction, meaning less heat loss.”

Design

There are lots of things to consider when choosing an electric patio heater. They come in a lot of different designs, including floor standing columns, wall mounted, bar-shaped heaters with their own stands, arch designs (which need to be fixed to the floor), parasol heaters and ceiling-mounted pendant designs.

Many look functional rather than super stylish, and the lack of naked flames can make them less aesthetically and emotionally appealing.

Different types of electric heater work at different temperatures. Short-wave (near infrared): operate at up to 2,700ºC. These are low-glare quartz, tungsten and halogen heaters that emit an orange glow. The warmth they produce feels hotter but isn’t so easily absorbed by the skin. Ideal for cold, exposed locations, these types of heaters are generally the cheapest.

Long-wave (far infrared) heaters run at sub 500ºC temps. These are no-glare heaters that produce a gentle warmth easily absorbed by the body. High-end, efficient ceramic heaters that work best in sheltered, undercover situations.

Middle-wave or medium infrared runs at 500-800ºC. These are the ultra-low glare heaters with characteristics of both short- and long-wave heaters.

An infrared heater warms people and objects directly using radiant heat, in the same way the sun does. This is completely safe and more efficient than heat sources that rely on convection. Heaters are rated by their heat output, in BTUs or Watts, and heating span – the area they will heat in m2, or how far the heat will reach in metres. The maximum distance the heat will reach from an infrared heater is 3-3.5m.

Maintenance

Electric heathers are low maintenance. Halogen and quartz elements last 3,000-5,000 hours; carbon fibre and ceramic about twice as long.

Safety

There are two options for electric heaters: fix them permanently in place and get them wired in by an electrician. Or choose portable models with extension cables and bring them outside when you need them, then take them in at the end of the evening. Because of the very high temperatures the elements can reach, if there are children in the household, many people feel safer getting the heaters fixed permanently out of reach. Stephen Hankinson, from Electric Radiators Direct, says, “Have your electric outdoor heaters hardwired by an electrician to guarantee full protection against the elements. Plus, make sure they’re positioned a safe distance from surrounding objects and out of reach of children. You should also refrain from covering the heater during usage and ensure patio heater cables are neatly organised to prevent tripping hazards.”

For electrical equipment that is going to be used out of doors, the ingress protection IP rating is important. The second number of this figure rates how waterproof a product is: the higher the numner, the more waterproof. A heater should have a minimum rating that ends in a 4 (eg IPX4 or IP24) if it will be under cover outdoors. If it’s going to be fully exposed, aim for an IP rating of IPX6 or above.

Running costs

Based on the average cost of electricity of 24.50p per kWh, the cost of running a 3kW electric heater for an hour is 3 x 24.50p = 73.50p an hour. Obviously, the cost will vary depending on the efficiency and power output of the heater and the price of electricity. If you are getting your heaters wired in, you could get a motion sensor, or timer button, to reduce electricity use, though high-end electric heaters now come with remote controls and app control.

Sustainability

Stephen Hankinson says, “For those seeking a sustainable solution, infrared heating emerges as the top choice. It’s 100% efficient at the point of use and provides direct warmth that isn’t lost easily, so there’s zero energy waste. Plus, when coupled with renewable energy sources, infrared patio heaters offer a fully carbon-neutral alternative.”

Of course, the carbon footprint of electric heaters ultimately depends on how clean the generation of the electricity powering them is, but they don’t generate carbon dioxide at the point of use – nor smoke nor particulates, of course.

Bioethanol firepits

Some of the coolest, sleekest, and most contemporary outdoor heaters burn bioethanol, a renewable fuel that burns efficiently and cleanly.

Sustainability

Bioethanol is usually made from crop waste, such as the molasses left over when sugar beet is processed to make sugar. The plant material is fermented to convert the sugar into ethanol, a type of alcohol. It does produce carbon dioxide when it burns but, as it is a renewable source of energy, it is generally thought to be carbon neutral. Bioethanol burns cleanly, producing no smoke or ash, so you can even use it indoors without a chimney.

Running costs

Like most things, bioethanol is cheaper the more you buy. A litre of bioethanol costs between around £3.50 and £7, depending on the quantity you buy. But you probably won’t want to buy too much in one go because of the problem of storing a flammable liquid. The amount of fuel your heater or firepit uses will depend on how high you have it on. In windy conditions, you will use more fuel. If we take the example of a firepit that burns for ten hours on 8-litres of fuel, say we pay £5 a litre for the fuel, the cost of running the firepit is £4 an hour (8 x 5 /10). Obviously, the cost of running bioethanol heaters will vary considerably according to the size of the firepit, how high you have it running, and how much you pay for your fuel. But generally running bioethanol heaters is pretty expensive.

Design

Bioethanol firepits and firetables are some of the most stylish around. Just make sure you buy one designed for use outside. And choose stainless steel if you can afford it, as it will resist rust better than a powder-coated model. As with the other heaters we’ve looked at, the heat output is measured in BTUs, Watts and in terms of the area that each heater will warm up.

Maintenance

Bioethanol heaters require very little maintenance. But you should always use a cover, and bring it indoors for the wettest part of the year.

Safety

Biofuel heaters have real flames so you need to take all the usual safety precautions that you would take with any other live flame – keeping children and animals away and flammable items at a distance. Choose a firepit with a flame guard and don’t leave it unsupervised.

Ethanol is highly flammable so don’t refill your heater while it is still hot, and carefully clear up any spills. Always follow the manufacturer’s instructions on using and refilling your heater.

Propane, bioethanol or infra-red, which is best for you?

Choosing the right patio heater comes down to what kind of heat you want and the effect that you want. If you want a real flame for the look, then a gas patio heater (propane or bioethanol) is the way to go, with a range of options, including fire tables, pillars and pits. While a little more expensive to run, bioethanol is the more sustainable option.

For direct heat and efficiency, and lower running costs, infrared heaters are the best choice. They’re not as nice to look at, but as they can be mounted permanently, you can integrate heaters in the design of an outdoor space to hide the heaters from view, while positioning them so that their heat delivers the most impact.