Everything About Space Heaters You Didn't Know

Every winter, the same myths circulate about electric heaters. This one is energy-saving. That one doesn't dry the air. This one burns oxygen. Allow me to explain, one by one, why almost everything you've read in heater marketing copy is wrong — and what actually matters when you're picking one out.

All Electric Heaters Are 100% Efficient. Full Stop.

This is the foundational fact that renders the entire «energy-saving heater» product category logically incoherent. Every watt of electricity you put into any electric heater comes out the other end as heat. There is nowhere else for it to go. An electric current passing through resistance generates heat — that's Joule's law. Whether the heater costs $30 or $300, whether it uses infrared radiation or convection, whether it has a ceramic element or a nichrome wire: 1 kWh of electricity in equals 3.6 MJ of heat out, every time.

What actually determines your heating bill is how much heat escapes your home — through walls, windows, the ceiling, the floor, and ventilation. If your home loses 1 kW of heat to the outside, you need to supply 1 kW of heating power to maintain temperature, regardless of which heater you use. A «premium energy-saving heater» that claims to reduce your bills by 20-30% is making a physically impossible promise.

Heaters Do Dry the Air — But Not Because of the Heater

The claim that certain heaters «don't dry the air» is technically meaningless. When you heat cold winter air, its relative humidity drops — not because any moisture is being removed, but because warmer air can hold more water vapor, so the same absolute amount of moisture represents a lower relative humidity at higher temperature.

Consider the numbers. Outside air at -15°C with 80% relative humidity contains very little water vapor in absolute terms. When you bring that air indoors and warm it to +20°C, the same air now has a relative humidity of only about 6.6%. A psychrometric diagram makes this inescapable. The only way to add humidity back is with a humidifier — and this is equally true regardless of whether your heater is an oil radiator, an infrared panel, or a convector.

Nobody Burns Oxygen

Heaters do not burn oxygen. Combustion requires a fuel — electric resistance heating involves no chemical reaction, only the conversion of electrical energy to thermal energy. The myth probably originates from two real phenomena that get conflated:

• Inadequate ventilation. Humans need 30 to 60 cubic meters of fresh air per hour. In a tightly sealed room, CO₂ accumulates and oxygen concentration falls slightly — not from the heater but from breathing. The result is drowsiness and headaches.
• Burning dust. On heaters with very hot surfaces — particularly convectors with bare nichrome wire elements — dust settles on the heating element and chars. This produces real combustion products and a characteristic smell. It's unpleasant and mildly unhealthy, but it has nothing to do with oxygen depletion.

Convectors

A convector works by drawing cool air in at the bottom, passing it over a hot heating element, and releasing warm air at the top. They are simple, inexpensive, silent, and compact. The main disadvantage of cheap convectors is that the heating element — traditionally bare nichrome wire — operates at very high temperatures, which is precisely what chars the dust that settles on it.

Modern convectors replace the bare wire with a tubular heating element (TEN) surrounded by aluminum fins. The fins increase the surface area dramatically, which means the element can transfer the same amount of heat at a much lower surface temperature — typically well below 200°C rather than above 600°C for bare wire. Less burnt dust, longer life, better safety.

One practical note: a convector must be mounted vertically. If you lay it on its side, the airflow pattern breaks down, the element overheats locally, and you will eventually have a fire hazard.

Oil Radiators

An oil radiator is a sealed metal cabinet filled with mineral oil, with a heating element immersed in the oil. The oil conducts heat to the large metal fins, which then radiate and convect heat into the room. The key advantage is surface temperature: the oil acts as a thermal buffer, spreading the heat over a large area, so the exterior surface never gets hotter than about 60-80°C. At that temperature, dust doesn't char — it just sits there, and you can wipe it off with a damp cloth without disassembling anything.

Oil radiators are heavy, slow to heat up, and expensive to manufacture. They're ideal for bedrooms and situations where you want quiet, gentle heat with no smell. They're poor choices if you need to heat a room quickly.

Fan Heaters

A fan heater moves air through a heating element at high speed, producing rapid warming. It heats a room faster than any passive convector and can be aimed directionally. The downsides are noise and — with cheaper models using nichrome wire elements — burnt dust.

Ceramic PTC (positive temperature coefficient) fan heaters are a significant improvement. A PTC element has a resistance that rises sharply above a certain temperature, which acts as automatic self-regulation: as the element heats up, its resistance increases and its power output drops, settling at an equilibrium temperature of around 200-250°C. This is still hot enough to char dust, but the self-regulating behavior makes the heater safer and more consistent. It cannot overheat even if airflow is partially blocked.

Infrared Heaters

Infrared heaters work differently from convectors and oil radiators: instead of heating the air, they emit electromagnetic radiation in the infrared spectrum, which is absorbed directly by people, furniture, walls, and floors. The Stefan-Boltzmann law governs the output: radiated power scales with the fourth power of absolute temperature, which means a small increase in element temperature produces a large increase in radiated power, allowing compact high-power designs.

The practical consequence is uneven heating. Stand in the beam of an infrared heater and you feel intense warmth on one side while the other side remains cold. Step out of the beam and the warmth disappears almost immediately, because the air itself is barely heated. This can be comfortable in some situations (a workshop, a patio) and deeply unpleasant in others (a living room where you want uniform ambient warmth).

Infrared heaters come in several subtypes:

• Quartz ceramic panels: Low power, decorative, designed more for aesthetics than serious heating.
• Micathermic panels: A niche category with no clear practical advantage over oil radiators or ceramic convectors.
• Aluminum ceiling panels: Effective for industrial spaces and garages where floor-level obstacles would block a conventional heater.
• High-temperature lamps (nichrome, carbon, halogen): The most intense infrared output; used in bathrooms and outdoor heating. Require care around flammable materials.

Thermostats: The Detail Everyone Ignores

A simple bimetallic thermostat controls the heater itself — it switches the element on and off based on the temperature at the heater's surface, which is not the same as room temperature. This produces crude regulation with significant oscillation. For anything beyond basic use, a room thermostat that measures air temperature at a fixed point in the room and switches the heater accordingly is far more effective.

Electronic thermostats vary enormously in quality. The best ones use solid-state switching (no relay click, no contact wear) and PID algorithms that anticipate the room's thermal behavior rather than simply reacting to it. Whether a given product actually implements these features is often impossible to tell from the marketing materials — the terms are frequently used loosely.

Safety Recommendations

• Choose metal-bodied heaters over plastic ones. Plastic heaters that overheat can ignite; metal heaters deform and trip a safety cutoff.
• Never plug a heater into an extension cord or power strip. Heaters draw sustained high current; most extension cords are not rated for this and will overheat.
• Maintain at least 1.5 meters of clearance between the heater and any combustible material — curtains, furniture, bedding.
• If your home has old aluminum wiring, have an electrician verify it can handle the load before using any high-wattage heater.
• Verify that any heater you buy has tip-over protection (automatic shutoff if knocked over) and thermal cutoff (automatic shutoff if the element overheats).

How to Actually Choose

There is no universally «best» heater, and the choice depends on the specific situation. Some principles that hold consistently:

• Larger surface area at lower temperature is safer and more comfortable than smaller surface area at higher temperature — the same amount of heat delivered more gently.
• Avoid unnecessarily complex electronics if you don't need them; more components means more to fail.
• For infrared heaters specifically, verify that replacement elements are available before buying — some models become paperweights when the element burns out.
• If you're heating a space continuously, no heater will reduce your energy bill. Only reducing heat loss through insulation, draft-proofing, and window upgrades will do that.

Physics does not negotiate. A heater is a device for converting electricity to heat. The only variables under your control are comfort, convenience, and safety — not efficiency, which is already at its physical maximum for every model on the market.