The two most common space heaters on the market are convection heaters and radiant heaters. They’re both effective ways to heat small spaces, but operate in radically different ways. Convection heaters warm the air. Radiant heaters warm your body, which leads many consumers to ask, what’s more effective, convection heating or radiant heating?
How Do Convection Heaters Work?
There are three ways to heat an object: conductive heating, convection heating, and radiant heating. Conductive heating occurs when objects of different temperatures come into direct, physical contact. Energy is transferred from the warmer object into the colder object until the temperature of both objects is exactly the same. It’s what happens when you drop an egg into a frying pan or accidentally bump your hand against a hot stove.
Convection heating occurs when a warm object is placed in a fluid medium, like water or air. The thin layer of molecules in direct, physical contact with the object heat up through the process of conduction and causes them to expand. As they do, they move up and away from the object, displacing the cooler, denser molecules above them. They’re forced to drop down and come into contact with the heat source which warms them up, forcing them to expand and displace more air, which gets heated in turn. This is what is known as a convection current. It’s what happens when you heat a pot of water on the stove or turn on a convection heater in a cold room. Because air is a poor heat conductor, convection heaters work slowly, gradually warming the air until it’s reached a uniform temperature.
Types of Convection Heaters
There are five types of convection heaters: oil, ceramic, water, fan heaters, and furnaces. Each works on the same principle, but generates and distributes heat in different ways.
|Oil Filled Heater||Generate heat using an electric resistor connected to heating fins filled with small amounts of diathermic oil. When energy is supplied to the resistor, the heat is generates is absorbed by the foil in the fins, which warms up the air around it|
|Ceramic Heater||Generate heat by running electricity through metal coils attached to ceramic plates. The ceramic plates absorb the heat from the coils and warms up the surrounding air. Normally more compact than oil filled heaters|
|Water Heater||Generate heat with an electric heating element inside a metal tube filled with water. As the heating element warms up, it turns the water into steam, which warms the surrounding air instead of boiling off. Similar to oil filled heaters, but faster because water conducts heat better than oil|
|Fan Heater||Fans are an additional feature built into convection heaters to enhance their effectiveness. They force air over the heating elements and blow it out into the room in order to increase the speed at which air is heated and distributed. Significantly nosier than ordinary convection heaters|
|Furnace Heater||The main component in central heating systems, normally kept in basements or mounted on walls. Generate heat by burning oil or gas and use ducts to vent warm air into your home through grills in the floor or wall|
All convection heaters come with a built in thermostat that regulates the unit’s heat output. When the ambient temperature drops below your pre-set level, it activates the heater. Several convection heaters also come with timers, so you can program them to begin heating your home, office, or apartment before you arrive.
How Do Radiant Heaters Work?
As the name implies, radiant heaters work by generating infrared radiation. All objects radiate energy in some form, at a rate proportional to their temperature. The infrared energy from radiant heaters travels out in the invisible, electromagnetic waves that get absorbed by the objects in their path. If you’ve ever sat in front of a campfire, you’ve experienced radiant heat.
Radiant heat differs from conduction or convention in that it’s directional and unaffected by the medium it travels through and they don’t lose heat as they travel through the air. The waves move out in a straight line until they’re absorbed by your clothes, skin, and furniture, which means they warm you up very quickly.
Types of Radiant Heaters
There are several different ways of generating radiant heat, reflected in the different styles of radiant heaters available for your home. Some are ordinary space heaters, while others are built into the house itself.
|Electric||Generate heat by running electricity through metal heating coils. Commonly used in space heaters, but is also used in heaters mounted to floors or ceilings. Reflective housings direct the heat where it’s needed|
|Gas||Generate heat by burning gas and using the warm air to heat radiant tubing, which emits radiant heat as its temperature rises. Require additional ventilation systems to prevent waste fumes from contaminating the air|
|Floor||Generate heat by warming a series of hot air tubes, water tubes, or electric cabling beneath your floor. The heat is transferred to concrete, plywood, or ceramic tiles, which radiate it into the room. Hot air tubes are normally heated using solar energy, while water tubes are normally heated by broilers pumping up hot water|
|Radiant Panels||Generate heat by warming electric cabling or hot water tubing connected to aluminum panels on your floor or ceiling that radiate heat out into the room|
Radiant heaters are also a popular way to heat bathrooms. The heat from the infrared rays won’t be disturbed by steam fans.
What Type of Heater Heats Fastest?
Deciding whether radiant heating or convection heating is more effective depends on whether you’re trying to warm yourself or the room. Rooms with poor insulation, drafts, or high ceilings are very difficult to heat with a convection space heater. The warmth they generate seeps out into the surrounding environment or gets spread out over an area so large that it either can’t be felt or becomes wasteful. Air is a poor heat conductor.’
Where radiant heaters struggle is any place where you want to move around comfortably in the same area. Because their heat is so focused, radiant heaters can’t warm anything outside their field of view and because electromagnetic waves spread out as they travel from their source, you have to be physically close to the heater in order to feel its heat. All of which makes them an excellent way to heat one or two individuals, but very bad at heating rooms. Their heat’s just too confined. Convection heaters, though not as efficient, heat enclosed spaces very well, allowing you to move about without feeling cold or chilly. They take longer to warm you up, but they’re what you need if you want a constant, long-term heating solution.Because the electromagnetic waves they emit don’t interact with the air, radiant heaters don’t suffer from these problems. They provide immediate warmth to all people and objects directly in front of them, and because objects retain heat better than air, heat from radiant heaters takes longer to dissipate, so objects stay warm even after the heater’s been turned off. They can even be used outdoors. Their infrared technology isn’t not susceptible to winds or drafts.
As personal heating systems, convection heaters and radiant heaters have much to recommend them. Convection heaters work more slowly and less efficiently, but provide sustained heat over a long time and larger areas. Radiant heaters provide a concentrated beam of heat that warms people and objects very quickly, but only in small areas. Despite their drawbacks, both convection heating and radiant heating are more effective when used in personal space heaters rather than in large household systems. Convection furnaces and radiant heating panels heat large areas, but at a much higher cost. Space heaters use less energy to heat smaller spaces, which saves you money in the long term. Some modern space heaters, like the NewAir AH-470 Flat Panel Space Heater, even combine the two technologies to improve their efficiency and provide more heat faster.