Know the code. Before you begin looking for a patio heater or, especially, a fire pit, familiarize yourself with any local ordinances that might regulate their size, materials or use.
How much space do you need to heat? Most free-standing propane heaters have a heat output of 40,000 Btu or more, and gas fire pits can be rated similarly. Manufacturers often claim this can raise outdoor temperatures by anywhere from 10 to 25 degrees within a radius of nine feet. However, owner-written reviews indicate these estimates are exaggerated. In reality, the heating range is more like three to five feet or less in cold, windy weather. The smaller tabletop models, which produce only 10,000 Btu or so, may only provide warmth within a couple of feet of the heater. Wood-burning fire pits don't carry Btu ratings -- their only purpose is to contain a fire that you build inside of it. If you want to heat a large area, experts advise placing multiple heaters eight to 20 feet apart.
What is the weather like in your area? Patio heaters work best in mild climates. If you live in a very cold or windy area, you may need multiple heaters to provide enough warmth. Wind can also affect heaters in other ways. Propane heaters may be harder to light, and open flames of a fire pit could blow out if the wind is strong enough. A high wind also poses a tipping issue for narrow heaters, especially lighter tabletop models. If you live in a windy area, it's especially important to choose a patio heater that is heavy and stable, or consider a radiant electric heater. The best models have a switch that will automatically shut the heater off if tipped. Finally, if it rains frequently in your area, look for a model with a rust-resistant finish. If you choose a fire pit, make sure it comes with a cover to keep it from filling with rainwater, or that one is available as an option.
Do you want to move the heater around? Many fire pits -- particularly propane-fueled ones -- are very heavy and will be all but impossible to move once you've set them up. Some are intended for permanent installation. Smaller, wood-burning fire pits, by contrast, can be moved around the patio or even taken along on trips. Tabletop propane heaters are very portable if they use a 1-pound propane cylinder but not when hooked up to a heavy 20-pound propane tank. Free-standing propane heaters are usually weighted to keep them from tipping over, so if you want to move yours around, look for a model equipped with wheels. Electric heaters are limited to outlet availability, as they must be plugged in.
Can someone help with the assembly? According to reviewers, assembling many of the heaters in our report is really a two-person job, despite what the manufacturer promises. If you plan to assemble the unit on your own, choose a model that is fairly simple to build.
Do you have children? Electric patio heaters are the most kid-safe type since there's no flame. Propane heaters often come with features to make them safer to use around children. Look for child-proof connections, well-balanced bases and most importantly, an automatic tilt shut-off feature, which shuts off the heater if it tips over. Also, make sure the heat-producing parts are well above a child's height and that models with wheels don't move when they are standing. Fire pits have open flames and/or sides that can get very hot to the touch. They should not be used around children without adequate adult supervision.