Electric Air Heaters

An electric heater is a fan heater: a fan pushes air across a hot heating element (a resistance coil or a ceramic PTC element) and blows the warm stream into the room. It consists of a housing, a heating element rated at about 2–30 kW, a fan, a thermostat and a thermal cut-out. Models up to 3.3 kW run from a 230 V socket, while more powerful ones need a 400 V three-phase supply; the unit produces no exhaust and releases almost 100% of the energy as heat.

Consumption equals the power rating: a 3 kW unit draws 3 kWh per hour and a 15 kW unit draws 15 kWh. At a rate of about 1.00 PLN per kWh an hour costs roughly as many currency units as the power in kW: 3 kW is about 3 PLN, 9 kW about 9 PLN, 22 kW about 22 PLN. In reality you pay less, because the thermostat switches the element off and the unit runs in cycles, often 40–60% of the time.

A 230 V (single-phase) heater runs from a wall socket and reaches up to about 3.3 kW, because a 16 A circuit will not carry more — it suits the home, garage and a small workshop. A 400 V (three-phase) version draws power from a three-phase socket and offers from about 4 kW to 30 kW, spreading the load across three phases. Halls, warehouses and building sites need a 400 V unit, which an electrician connects.

For an insulated garage a rough figure is 0.06–0.1 kW per m², so for 20–25 m² a 2–3 kW heater from a 230 V socket is enough. A sheet-metal or poorly insulated garage sizes closer to 0.1–0.15 kW/m², so for the same 25 m² a 3–5 kW unit is a better pick. Above 40–50 m² you usually move to a 400 V supply and power from about 9 kW upwards.

For halls and building sites power is sized from the cubic volume: for poorly insulated spaces about 0.08–0.1 kW per m³. A 100 m² hall 3 m high is 300 m³, so roughly 24–30 kW — a 400 V model such as the Master B 30. A tent of 100–150 m³ is warmed by 9–15 kW. For larger areas compare electric heaters with oil and gas units rated above 30 kW.

An electric heater produces no exhaust and no carbon monoxide, so it runs in closed halls, garages and workshops without extraction ventilation — unlike an oil or gas unit. It is protected by a thermal cut-out that shuts the element off on overheating and by a housing of a suitable IP class. A 400 V model is connected by an electrician. Do not block the air inlet or outlet and keep about 0.5–1 m of clearance from flammable materials.

An electric heater turns almost 100% of the energy into heat and makes no exhaust, so it heats with no flue, but the cost per kWh of energy is higher and power is capped at about 30 kW. A fuel-fired heater (oil or gas) burns fuel, reaches outputs above 50–100 kW and a lower cost per unit of heat, yet it needs a chimney or heavy ventilation. Choose electric for enclosed interiors and fuel-fired for large, well-ventilated halls.

A coil element is a resistance wire that heats to a high temperature — it is cheap and delivers full power at once, but it can scorch dust. A ceramic PTC element (positive temperature coefficient) limits its own temperature: as it heats up its resistance rises and current draw falls, so it does not scorch dust and lasts longer. PTC models such as the Master B 2 PTC are safer for rooms with people; coil units are cheaper in the 15–30 kW range.

Most electric heaters have a built-in thermostat, and industrial models let you connect an external one. You set the target temperature, for example 15–21°C: once it is reached the element switches off and starts again when the temperature drops by 1–2°C. Thanks to this the unit runs in cycles and uses less power than heating non-stop. For a hall choose an electronic thermostat accurate to ±1°C and set the lowest value you can.

An electric fan heater and a convector heater both turn practically 100% of the energy into heat, so at the same power and time they cost the same — 2 kW for an hour is about 2 kWh whatever the type. The difference is in heat distribution: a fan heater raises the temperature quickly and, with a thermostat, switches off sooner, so for fast warm-up it can be more economical. A convector heats more slowly and more quietly.