Infrared heater power requirements – how to choose the right solution?

When choosing infrared panel heaters, one of the most common questions is: how powerful should the heater be, and how many are needed?

The answer is not universal — it depends on factors such as room size, insulation quality, ceiling height, ventilation, and the intended use. In this article, we will look at the main principles and share professional recommendations based on Sundirect’s practice.

1. Thermal transmittance (U-value) and insulation

The thermal transmittance (U-value) of a building’s envelope determines how much heat escapes through the walls, roof, windows, and other structural elements.

High U-value → greater heat loss

Low U-value → better insulation → lower power requirement

The U-value does not directly indicate how many heaters are required, but it helps to estimate the total heating demand — which can then be allocated across the individual panels.

2. Recommended Power Guidelines

The general rule: the poorer the insulation, the more watts per square meter are required.

Insulation level Power per m² (approximate)

Old/poorly insulated building 50–70 W/m² or more

Moderately insulated building 35–50 W/m²

Energy-efficient / high-quality insulation 20–30 W/m²

👉 Sundirect example: they recommend around 50–70 W/m² for well-insulated rooms, but up to 100–150 W/m² for poorly insulated spaces.

3. Recommendation: Always Choose Slightly Higher Power

A best practice — and something widely recommended by professionals — is to round the calculated power requirement up. Sundirect clearly states this in their guidelines:

“Always round up the required power. It is better to have slightly more power than too little.” – Sundirect

Why is this smart?

Safety margin for heat loss

Real-life conditions are rarely perfect. Hidden air leaks, weak insulation points, or lower outdoor temperatures can all increase heat demand. Extra capacity covers these uncertainties.

Comfort assurance

If the system is underpowered, panels may need to run at full capacity and still not provide enough heat. With a small reserve, panels operate at lower intensity, last longer, and ensure comfort.

Flexibility and control

With extra capacity, thermostats and smart controls can reduce power whenever full output is not required. It’s better to scale down than struggle with insufficient heating.

👉 Practical advice: add a 15–20% safety margin to your calculated power for optimal performance.

4. Placement and Distance of Panels

Correct installation is just as important as choosing the right power:

Panels should be placed symmetrically for even heat distribution.

It is often better to install several smaller panels than one oversized unit.

For ceilings above 2.7–3 m, consider higher power or special mounting solutions.

Sundirect recommendation: the optimal distance is about 3–4 meters between the panel and the heated surface.

5. Additional Factors to Consider

Thermostat integration

Modern controls allow up to 10 panels to be connected to a single thermostat (Sundirect), ensuring precise regulation and reduced consumption.

Electrical capacity

The wiring must support the total load with a safety margin, especially if multiple panels run simultaneously (Sundirect).

Zoning the space

Focus heating where people spend the most time instead of heating the entire space evenly.

Room specifics

High ceilings, open-plan layouts, or spaces with frequent air exchange will require higher overall capacity.

6. Conclusion

Always select slightly more power than your exact calculation. This safety margin ensures your system can handle unexpected heat losses, guarantees comfort, and extends the life of your panels.

“Always round up the required power. It is better to have slightly more power than too little.” – Sundirect