Patio heaters are heaters for use in open spaces. They are popular for domestic use and outside dining areas particularly in open cafes and restaurants with outdoor seating.
They usually heat a radius of 10-20 feet. However the radius varies according to the model and ambient atmosphere. The heaters usually raise the temperature from 10-30 °F.
Patio heaters are not designed for chilly winters as that would require a heavy duty heater with enormous energy consumption. They are used for relatively little increase in ambient temperature and particularly used in the evenings of late fall and early spring.
Patio heaters run on a variety of fuel like natural gas, propane, butane, kerosene etc. Some electric models are also available. The natural gas models are popular because they use the same fuel system as an outside grill. Portable heaters have a portable cylinder attached to the heating unit.
The principle used in most heaters is to heat using radiated heat and not convection. As a lot of energy gets used up in heating air for convection heating and very less percentage of heat is left for the user convection heating is not feasible. Radiative heating patio heaters are more economical as they provide heat to the user and air is not heated.
The heaters are provided with a heavy aluminum reflector at the top to direct the heat downwards and outwards from the heater. These aluminum reflector type models are termed as mushroom patio heaters or umbrella patio heaters. The pole is usually 3 to 7 feet tall. Ceiling patio heaters are also available in the market. These are installed permanently and need less maintenance than the portable one.
Pyramid Flame Gas Patio Heater
Heaters radiate anywhere up to 35,000 BTU (British Thermal Units). The emitter reaches a temperature up to 1150 °F. This causes bluing of the stainless steel. Also a brownish color develops on the emitter which appears like rust. However there is no cause for alarm as this brownish tint is normal and is not rusting of the unit.
The cost of patio heaters varies as per the model. A reasonable quality patio heater may cost between $100 to $300. Look for safety features like tilt switches, sealed burners, emergency cut off valves, flame controllers and electronic ignition systems etc when purchasing.
These items are available in shops where natural gas or butane is available. Some specialty shops for home decorating also keep patio heaters. Do not treat them as toys. It is prudent not to let children operate them.