Heating/ CALCULATOR
Radiator output at lower water temperature
Estimate how a radiator’s published heat output changes at a different supply, return and room temperature.
Use the manufacturer output at the stated rated temperature difference.
Often ΔT50 for EN 442 radiator data; verify the product sheet.
Water temperature entering the radiator at the condition being checked.
Water temperature leaving the radiator at the same condition.
Use the intended indoor design temperature.
Use the manufacturer value when available; 1.3 is a common screening value for panel radiators.
Count only radiators with the same published output and operating condition.
Mean water temperature
40.0 °C
Actual mean-water-to-room difference
20.0 °C
Estimated output per radiator
456 W
Estimated total output
2,279 W
Output retained versus rated condition
30.4 %
Interpretation:This operating condition provides about 455.79 W per radiator and 2,278.97 W in total—30.39% of the published rated-condition output. Compare it with the room-by-room design heat loss.
Arithmetic mean water temperature, steady operation and the entered radiator exponent. Published rated output must use the entered rated temperature difference. Flow limits, uneven temperatures, enclosure, paint, air pockets, valve authority, pipe loss, intermittent control and manufacturer-specific corrections are excluded. Use product data and a room-by-room design for final selection.