Getting the heat emitter sizing right is one of the most consequential decisions on a healthcare or education refurbishment — and one of the most commonly rushed
This is critical. The surface must stay at or below 43°C even when the heating system is working at full capacity — not just under normal operating conditions. A radiator that meets the limit on a mild day but exceeds it in cold weather provides false assurance.
In short, the 43°C rule exists because the inability to feel or respond to pain is itself the hazard, and the building's heating system must compensate for what the occupant cannot do for themselves.