How to Choose an Infrared Heater – Type, Power and Placement According to the Space
How to Choose an Infrared Heater – Type, Power, and Placement Based on Space
Infrared heaters are among the fastest-growing categories of heating technology on the Slovak market. The reason is simple: they heat instantly, require no piping, work both outdoors and indoors, and consume exactly as much energy as you actually need. Yet we still see the same mistakes over and over – customers buy a unit that's too weak for a garage, one that's too powerful for a small office, or they mount the right infrared heater in a completely unsuitable location. The result? Dissatisfaction, a surprising electricity bill, and the feeling that "this heating doesn't work."
This article will guide you through the entire decision-making process – from understanding the physical principle, through selecting the right type, to specific recommendations for different types of spaces. If you're looking for a specific power calculation for a garage, terrace, or workshop, also check out our companion article What Infrared Heater Power Do I Need for a Garage, Terrace, or Workshop.
Why an Infrared Heater Works Differently Than a Convector or Boiler
Classic convectors and radiators heat the air – it warms up, rises, and circulates around the room. This principle has several disadvantages: it takes time for the air to reach the desired temperature, heat concentrates near the ceiling, and any ventilation practically cools the room back to zero. In addition, air movement stirs up dust and allergens.
An infrared heater works completely differently. It emits electromagnetic radiation in the infrared part of the spectrum (wavelengths of 0.7 to 1,000 micrometers), which passes through the air without loss and directly heats objects, surfaces, and people within the range of the rays. The air heats up secondarily – from the heated surfaces. In practice, this means: you turn on the infrared heater and feel the heat almost immediately, similar to stepping out of the shade into the sun.
This property has significant consequences for selection and placement: an infrared heater must have a direct line of sight to the area it is meant to heat. A pillar, partition, or even a thick curtain can significantly reduce efficiency. On the other hand, an infrared heater works great outdoors, where a convector would be completely useless – outdoor air cannot be effectively heated.
Three Main Types of Infrared Heaters – Basic Overview
There are three distinct technologies on the market, each suited to different situations. For a detailed comparison, see the article Short-wave vs. Medium-wave vs. Dark Infrared Heaters – Which Type Is Right for You; here we summarize the most important points for making the right choice.
Short-wave (Bright) Infrared Heaters – Speed and Intensity
Short-wave infrared heaters operate with a wavelength of 0.7 – 1.4 micrometers and produce visible red light (hence "bright"). Their emitter temperature ranges around 2,200 – 2,700 °C. Energy is transferred extremely quickly and efficiently, and the penetration of the radiation is high.
Suitable for: industrial halls, spaces with high ceilings (8 – 15 m), exteriors, places where people come and go (tennis, futsal, logistics). Since they turn on and off instantly with no warm-up time, they can be controlled by motion sensors.
Not suitable for: long-term stays at low mounting heights, living rooms (the intense red light is distracting).
Medium-wave Infrared Heaters – A Compromise for Everyday Use
Wavelength of 1.4 – 3 micrometers, emitter temperature of 600 – 900 °C. Medium-wave models glow less, heat up in 1 – 2 minutes, and have a wider radiation angle. They are the "workhorses" of the category – found on restaurant terraces, in bathrooms, on construction sites, and in retail.
Suitable for: terraces, bathrooms, workshops, offices, garages, spaces with ceilings 2.5 – 5 m.
Dark (Wave) Infrared Heaters – Long-wave Radiation for Interiors
These operate with a wavelength above 3 micrometers, with an emitter temperature of only 200 – 400 °C. They emit no visible light – hence "dark." They have lower intensity but very even and pleasant heat, closer to the natural radiation of the human body. The unit heats up in 3 – 5 minutes.
Suitable for: living spaces, bedrooms, hallways, sanatoriums, spaces with ceilings up to 3.5 m where people stay for extended periods.
Key Parameters to Consider – What Really Matters
Power in kW – The Basis of the Entire Selection
Power is the most important parameter. A unit that's too weak will constantly run at maximum and still not adequately heat the space. A unit that's too powerful is needlessly more expensive and can be uncomfortable at low mounting heights. Basic reference values for well-insulated spaces with ceiling heights up to 3 m:
- Bathroom (6 – 10 m²): 0.5 – 1.0 kW
- Home office (15 – 25 m²): 1.5 – 2.5 kW
- Living room (25 – 40 m²): 2.5 – 4.0 kW
- Garage (20 – 30 m², uninsulated): 3.0 – 5.0 kW
- Workshop (40 – 80 m²): 5.0 – 10 kW (multiple units)
- Terrace (20 m², outdoor): 2.0 – 3.5 kW
- Industrial hall (200 m², 6 m ceiling): 20 – 40 kW (system)
For outdoor and uninsulated spaces, plan for a power output 1.5 to 2 times higher than for an equally sized insulated interior. Wind, open entrances, and cold walls significantly increase heat loss.
Mounting Height and Tilt Angle
Mounting height directly determines the radiation intensity at body level. The inverse square law applies: if you double the distance from the emitter, the intensity drops to a quarter. This has practical consequences:
- Too low (less than 1.8 m for a powerful unit) – risk of overheating, a burning sensation, safety hazard
- Too high (more than 5 m for a weak unit) – radiation disperses and effective heat doesn't reach people
- Optimal height for most indoor applications: 1.9 – 3.5 m
- For industrial spaces with ceilings 6 – 12 m: powerful short-wave units of 2 – 6 kW each
The tilt angle (the heater's inclination from vertical) is important for wall mounting. Most manufacturers recommend a tilt of 30 – 45° from the horizontal plane, so the rays are directed at body level rather than straight down onto the floor or against the far wall.
Power Supply – 230 V vs. 400 V (Three-phase)
Infrared heaters up to 2.5 – 3 kW are standardly on 230 V and don't require any special electrical work. Models above 3 kW are typically on 400 V (three-phase power supply), which may require an electrician and the availability of a three-phase connection. In households, this needs to be verified in advance – not every household has three-phase power in the garage or workshop.
IP Rating – For Damp and Outdoor Spaces
- IP20 – basic protection, indoor dry use only
- IP44 – protection against splashing water, suitable for bathrooms, covered terraces, garages
- IP65 – waterproof, suitable for outdoor use without cover
- IP67/68 – full immersion, for special industrial applications
If you're mounting an infrared heater on an uncovered terrace or in a garden, never choose a model with an IP rating lower than IP55. For more on the differences between outdoor and indoor models, see the article Infrared Heaters for Outdoor vs. Indoor Use – What Are the Differences and What to Consider.
Placement of the Infrared Heater – Ceiling, Wall, or Stand
Ceiling Mounting – Ideal for Most Applications
Ceiling mounting is physically optimal: the heater has a view of the entire room area, the rays are directed downward at a natural angle, the heater doesn't obstruct the space, and the risk of contact with it is minimized. For private households, garages, workshops, and industrial halls, this is the default choice.
Conditions for proper ceiling mounting: a solid ceiling (concrete, steel structure, solid beam ceiling), maintaining the minimum safety distance from flammable materials (usually 20 – 50 cm depending on power and type), horizontal position of the heater or the ability to adjust the angle. You can find a detailed guide in the article Mounting an Infrared Heater on the Ceiling or Wall – Procedure and Safety Requirements.
Wall Mounting – For Low Ceilings and Targeted Heating
Where ceilings are lower than 2.2 m (basements, some garages, older buildings), or where a specific work zone needs heating, wall mounting is a better alternative. The heater is placed at a height of 1.8 – 2.2 m on the wall and tilted at an angle of 30 – 45° downward into the space. The disadvantage is a smaller range and the need to ensure that there are no flammable objects or people in too close, prolonged contact within the line of the rays.
Portable Stands – Flexibility for Construction Sites and Events
Stand-mounted infrared heaters are ideal wherever mobility is needed: construction sites, seasonal events, market stalls, outdoor catering events, temporary warehouses. Disadvantage: they take up floor space, tip over more easily, the rays are at body height, and at higher power levels safe distances must be observed.
Choosing by Specific Type of Space
Garage
The garage is one of the most common applications. Most garages in Slovak households have an area of 18 – 36 m², ceilings of 2.2 – 2.8 m, and zero or minimal thermal insulation. This means high heat loss, including heat loss through the concrete floor and an unheated foundation slab in winter.
For a 20 m² uninsulated garage, we recommend 2.5 – 3.5 kW; for a 30 m² garage with an unheated adjacent space, 4 – 5 kW is fine. Type: medium-wave or dark infrared heater with a minimum IP44 rating (dust, possibly moisture). Mount on the ceiling above the entrance door or above the workbench. Watch out for safe distance from wooden shelves and flammable liquids.
If the garage is used only for parking a car (not as a workshop), you might consider an infrared heater with a motion sensor – it will turn on only when you're inside, which dramatically reduces consumption.
Terrace and Garden
For a terrace, you always need an outdoor model with an IP55 or IP65 rating, resistant to rain. Calculate power much more generously than for an interior – a 15 m² terrace may well require 3 – 4 kW, since heat escapes into open space and air flows freely.
For a covered restaurant terrace, ceiling infrared heaters of 2 – 3 kW for every 4 – 6 m² of seating. For an uncovered garden, only stand-mounted models aimed directly at the seating area are effective. More tips can be found in the article Infrared Heaters for Terraces and Gardens – How to Heat Outdoors Efficiently and Safely.
Bathroom
The bathroom is an ideal space for an infrared heater – small volume, need for rapid heating, short duration of stay. 0.5 – 1.5 kW is enough depending on size. Always require IP44 as a minimum; for mounting above a bathtub or shower stall, IP65. Dark infrared heaters are more suitable here than bright ones – they don't glow, don't distract, and provide pleasant, even heat.
Safety note: the infrared heater must be out of reach of a person in the bathtub (min. 60 cm from the edge of the tub horizontally), which is both a legal requirement and common sense.
Industrial Hall and Production Facility
For halls with ceiling heights of 5 – 12 m, short-wave infrared heaters with a power of 2 – 6 kW, arranged in a grid, are clearly the best choice. The distance between individual emitters depends on power and mounting height – typically 4 – 8 m apart. At a mounting height of 6 m and a power of 3 kW, the effective heating area of one emitter is about 12 – 18 m².
In halls where people work at machines or perform heavy manual labor at a stationary line, zonal heating proves effective: heaters only above workstations, not above the entire hall. This saves 40 – 60% of energy compared to heating the whole space uniformly.
Office and Living Spaces
Dark infrared heaters (long-wave) are designed for exactly this purpose. They don't create distracting light, provide pleasant radiation, and can be integrated into the ceiling design. Power for a 20 m² office in a well-insulated building: 1.5 – 2.0 kW. For a 30 m² living room with large windows: 3.0 – 3.5 kW.
In an office with many workstations, consider combining an infrared heater as supplementary heating with a central system as the base. The infrared heater quickly brings up the temperature when people arrive in the morning to a cold office, after which the system can regulate just to maintain it.
Workshop and Garden Shed
A garden workshop of 15 – 25 m² with a wooden structure needs 2 – 3 kW. Note here: a wooden structure means a larger safety distance from the ceiling and walls must be maintained (usually a minimum of 40 – 60 cm for more powerful models). Always read the manufacturer's technical data sheet regarding minimum protective distances – failure to comply can cause a fire.
Control and Regulation – From Thermostat to Smart Home
Choosing the infrared heater itself isn't enough – how you control it is equally important. An infrared heater without regulation is like a car without a steering wheel: you're moving, but you don't know where. Available options:
- Integrated thermostat – the simplest solution, the heater turns itself on/off based on temperature. Suitable for bathrooms and offices.
- External thermostat – more precise, placed in the right location (not directly under the heater), better regulation for larger spaces.
- Motion sensor (PIR) – economically advantageous for spaces with irregular occupancy (garage, storage, hallway). The heater turns on only when a person is present.
- Timer switch – suitable for workplaces with fixed working hours.
- Smart/WiFi control – control via app, integration with Google Home or Apple HomeKit, remote activation before arriving home.
Proper regulation can reduce energy consumption by 20 – 40% compared to manual on/off switching. For more on consumption and operating economics, see the article Electric vs. Gas Infrared Heaters – Comparison of Costs and Use.
Safety Requirements and Standards – What Must Not Be Overlooked
An improperly installed or selected infrared heater can be a source of fire or health risk. Overview of key safety requirements:
- Always observe the minimum protective distances specified by the manufacturer – from flammable materials (wood, textiles, plastics), but also from people in the case of high-power short-wave models
- For power outputs above 2 kW in a regular interior, require a fixed electrical installation (not an extension cord) and a protective earth
- In bathrooms, safety zones apply according to the standard ČSN 33 2000-7-701 (or the Slovak equivalent STN) – infrared heaters are not permitted in zones 0 and 1, and only IP44+ in zone 2
- Never position an infrared heater so that it is permanently aimed directly at a person's head (health risk from prolonged exposure to short-wave radiation)
- In spaces with flammable gases or vapors (paint shops, gas stations), infrared heaters are not permitted without special explosion-proof design (ATEX)
Common Selection and Installation Mistakes – From Practical Experience
After years of experience implementing heating projects, we still see the same mistakes over and over. Here are the most common ones and how to avoid them:
1. Underestimating power for an uncovered exterior. A customer buys a 1.5 kW infrared heater for a 20 m² terrace because "it's enough indoors." Outdoors on a terrace, that's a quarter of the required power. Result: a Christmas barbecue at 2 °C outside is cold. Always plan for a factor of 2.0 – 2.5 for uncovered exteriors compared to an equally sized interior.
2. A short-wave heater in the living room. A powerful bright infrared heater gives off strong red light and intense radiation, uncomfortable for prolonged stays. For living spaces, we choose dark or medium-wave models with a lower surface temperature.
3. Mounting on drywall without anchoring into a load-bearing profile or the ceiling. An infrared heater weighing 4 – 8 kg mounted on drywall alone poses a risk of falling. Anchoring must go into load-bearing material, not just into the cladding.
4. Ignoring safety distances. A heater too close to a wooden shelf or cardboard boxes is a fire risk. The manufacturer states minimum distances in the manual – they're there for a good reason.
5. One powerful heater instead of several weaker ones. For a long hall or large area, it's always better to distribute several smaller heaters evenly rather than have one "monster" in the middle. One 8 kW heater in the corner of a 60 m² hall will heat less evenly than four 2 kW heaters distributed around the hall.
6. Incorrect angle of a wall-mounted heater. A wall heater aimed horizontally directs its rays straight at the opposite wall, not at people. Tilt it 30 – 45° downward.
How to Properly Plan Your Purchase – Checklist
Before ordering, we recommend answering these questions:
- What are the dimensions of the space (m²) and the ceiling height?
- Is the space insulated, or is it an uncovered exterior / uninsulated garage?
- What is the power supply: 230 V single-phase, or 400 V three-phase?
- What is the intended mounting height?
- What is the surface of the ceiling/wall (concrete, wood, drywall), and is it possible to anchor into load-bearing material?
- Will the space be frequently used (long-term presence) or only visited briefly?
- Is there moisture, dust, or risk of chemical vapors present?
- Do you want a thermostat, motion sensor, timer, or smart control?
With answers to these questions, you'll be able to choose the right type, power, and model without the risk of a wrong purchase. If anything is unclear, questions about consumption, safety, and distances from objects are also addressed in our comprehensive article Frequently Asked Questions About Infrared Heaters – Consumption, Safety, Distance from Objects.
Frequently Asked Questions (FAQ)
What power infrared heater is suitable for a 25 m² garage?
For an uninsulated 25 m² garage with a ceiling height of around 2.5 m, we recommend a power output of 3.0 – 4.0 kW. If the garage is partially insulated, 2.5 – 3.0 kW is sufficient. Always plan with a margin, since a garage usually has an unheated concrete floor, including heat losses through the garage door.
Can I leave the infrared heater on overnight?
Yes, if it is properly installed, maintains safe distances from flammable materials, and has a thermostat or a switch with a protective function. We recommend using a thermostat so the heater regulates itself – this saves energy and extends its service life. For a bedroom, choose dark infrared heaters that don't emit distracting light.
Is an infrared heater safe for children and pets?
Yes, if properly installed and out of reach of hands. Ceiling mounting is ideal precisely because neither children nor pets can touch the heater. The radiation itself (heat) is as safe for children and animals as sunlight – only excessively long direct exposure to high-power short-wave models is harmful, which typically doesn't occur in home use.
How much does it cost to run an infrared heater per month?
It depends on the power and operating time. Example: a 2 kW infrared heater, electricity price of €0.22/kWh, operating 6 hours a day = 2 × 6 × 30 = 360 kWh/month = approx. €79/month at full power. In practice, the thermostat cycles the heater, and actual consumption is 40 – 70% of rated power, so real costs will be €30 – 55/month for this example. Efficient regulation significantly reduces operating costs.
What's the difference between cheap and more expensive infrared heaters?
Cheaper models usually have less durable heating elements (shorter lifespan), a simpler reflector (poorer radiation direction), basic or no regulation, and a lower IP rating class. More expensive models offer ceramic or carbon emitters with a longer lifespan, a more precise parabolic reflector, an integrated WiFi thermostat, a higher IP rating, and certifications. For intensive commercial use or outdoor use, the quality difference shows up very quickly – a cheap outdoor model lasts one to two seasons, a quality one 8 – 12 years.
Do I need to call an electrician to install an infrared heater?
For models up to 2.5 kW with a plug for 230 V, an electrician is not needed – you simply plug the infrared heater into a standard outlet. For power outputs above 3 kW on 400 V and for fixed wiring without a plug (cable connected directly to the electrical installation), it is a legal requirement that the connection be made by a professionally qualified person (electrician). Mounting on the ceiling or wall (drilling, anchoring) can be handled by a skilled DIYer, but electrical wiring for a fixed installation must always be done professionally – this isn't just a formality, but also a condition for an insurance claim in the event of a fire.
Conclusion – The Right Choice Pays Off Twice
Choosing an infrared heater isn't rocket science, but it does require thinking about several key parameters at once: type of radiation based on occupancy and space, power based on area and insulation, mounting height and angle based on layout, IP rating based on environment, and regulation based on usage pattern. A correctly chosen and installed infrared heater is a reliable, efficient, and practically maintenance-free heat source for 10 – 15 years.
If you're deciding between specific models or aren't sure about the power calculation, browse the entire infrared heater category on atria.sk – you'll find clear parameters there to help you choose. And if a problem arises during installation or the heater doesn't behave as expected, visit the article Common Infrared Heater Faults – Why It Doesn't Heat, Flickers, or Turns Off, which contains solutions to the most common problems.
Do you have a question on this topic?
Can't decide or dealing with a specific situation in your household? Write to us - we'll be happy to help.