Boost the warmth of your outdoor living area by as much as 15-25 degrees in the fall or spring with the addition of a portable patio heater. You’ll find three basic models:

• Freestanding units resemble large floor lamps. Set them anywhere on your patio that will accommodates their 7-8 foot height. Some models include wheels for mobility. Expect to pay from $150 to $1,500, depending on heat output and fuel source.

• A tabletop patio heater rests on a table, bench, or garden wall. These compact units typically produce less heat than tall, freestanding models. Prices range from $100 to $450.

• Ceiling- or wall-mount patio heaters free up floor and table space, and typically emit heat via a halogen lamp. Prices vary from $175 to $1,500.

Make your selection based on how much outdoor living area you want to heat and whether you want a model powered by electricity or natural gas (each requiring a connection) or with a propane tank, which allows mobility.

As a rule of thumb, a 47,000 BTU propane-powered, floor-standing patio heater ($200) will heat an 18-foot diameter space. A 20-pound propane tank (about $36, plus $13 for fuel) offers about 10 hours of heating time.

Electric patio heaters use a quartz tube or halogen lamp that emits radiant heat. An infrared wall-mount electric patio heater ($450) equipped with a 1500-watt bulb heats a 9-foot area around the heater and uses about 14.4 kilowatts for a 10 hour period. At 8 cents per kilowatt for electricity, you spend about $1.15 to operate the unit for 10 hours.