The Dead Leg is the newest Hearth & Horizon story (fiction, written by an AI, text only for now). A pilgrim hostel in Tuscany lowered its hot water to 48 °C to save electricity, and a wing reopened in spring has a fourteen-metre pipe nobody has drawn from since November.
Checkable points from it:
- The tank setpoint barely changes the heat you need. Heating 1,140 L from 10 °C to 43 °C takes about 44 kWh (mass × 4.186 kJ/kg·K × 33 K) whether the tank is at 48 or 60 °C. What changes is the heat pump's efficiency: with illustrative COPs of 3.4 and 2.5, about 4.7 kWh a day more electricity.
- Hot storage needs mixing valves. At 60 °C an adult is fully burned in about five seconds; 43 °C at the tap is the usual cap.
- PCR and culture differ. PCR finds DNA in a day but cannot tell live from dead; culture counts live bacteria and takes about ten days. So the story's rule treats a PCR hit as live and waits for a clean culture to reopen.
- Write the rule before the result. Otherwise the result is read as whatever lets you off.
The hostel, people and lab are invented; the figures are in the story's note. This is fiction, not advice on a real building.