Radiator Sizing Made Simple

AI-Powered Tool Based
At Heat Engineer, we're transforming the way heating professionals size radiators. Our advanced radiator sizing tool offers both manual configuration and a cutting-edge AI-assisted option to deliver fast, accurate, and standards-compliant radiator outputs.

Whether you're a heating engineer, installer, or consultant, our tool helps you streamline radiator selection with precision grounded in trusted industry methodologies.

How Our Software Supports Radiator Sizing

Built on Trusted Standards: EN442 & CIBSE Guide A

All radiator output figures generated by our tool are calculated in accordance with CIBSE Domestic Heating Design Guide Section 10 and adhere strictly to the EN442 standard, which is the recognised European benchmark for radiator sizing. This standard reflects a system design with:

  • Flow temperature: 75°C
  • Return temperature: 65°C
  • Room temperature: 20°C

This results in a ΔT (Delta T) of 50°C, commonly known as DT50, which forms the reference point for radiator output ratings.

AI-Enhanced Sizing - Faster, Smarter, Still Standards-Based

In addition to manual calculations, our tool now offers AI-powered radiator sizing. This intelligent assistant interprets room data from your heat loss calculations - including dimensions, insulation levels, glazing, and ventilation - to automatically suggest radiator outputs in watts.

Our AI leverages the same mathematical and design logic as the manual approach, but processes it in seconds, saving you time while eliminating guesswork.

Manual Input for Custom Radiator Selection

Prefer to use your own radiator models? No problem. When you select a custom radiator from the dropdown, you'll be prompted to input the radiator's manufacturer-stated output at DT50 (75/65/20) along with dimensions and other specifications.

Once these values are entered, our tool unlocks additional Mean Water Temperature (MWT) output results, helping you assess radiator performance under alternative flow/return configurations (e.g., 70/50, 55/45), which is critical for low-temperature heating systems like heat pumps.

Important Note: Heat Engineer Software accepts no responsibility for output figures that fall outside the EN442 standard, including outputs based on non-standard ΔT values.