Estimate a room requirement, then check whether an existing radiator is likely to meet it.
Screening estimate onlyThe room requirement is a simplified screening calculation, not a full heat-loss design. Radiator outputs have been checked against the official K-RAD September 2025 catalogue. For design work, complete a full room-by-room heat-loss calculation and check current manufacturer data.
Quick screening tool for estimating room heat requirement using simplified room factors, then comparing against radiator output data.
Important: This is a screening tool only. It uses simplified room factors for guidance and training purposes only. It does not replace a full room-by-room heat loss calculation, professional survey, manufacturer design data, MCS design work, heat pump design assessment or professional engineering judgement.
1. Room Estimate
Enter the room dimensions and building details to estimate the output required. This uses simplified room factors for training and screening only, not a formal heat loss calculation.
Enter the approximate total glazed area in the room. Use 0 if there is no window.
Training note: These building details are simplified room factors. They help trainees understand what affects radiator sizing, but they do not replace U-value calculations, external design temperatures or a full heat loss assessment.
2. Heating System Assumption
Use this to show trainees how lower-temperature systems reduce radiator output. These are simplified training comparisons, not heat pump design calculations.
Standard boiler / manufacturer rating
Uses the published radiator output at ΔT50. This is the normal comparison point for radiator output tables.
3. Existing Radiator Checker
Select the radiator type and size. Radiator outputs are based on published manufacturer performance data at ΔT50. Always confirm suitability using current manufacturer information and a full heat loss assessment where required.
4. Radiator Finder
After calculating the room estimate, use this to find radiator sizes that meet or closely match the estimated requirement. This helps trainees see how radiator type, height and width affect output.
Results
Date/time generated
Important result warning:
This tool provides a quick estimate only and must not be used as the sole basis for radiator sizing, heat pump suitability, system design, or equipment selection. If a radiator appears borderline or undersized, confirm suitability using a full room-by-room heat loss calculation and current manufacturer data.
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