A Landlord heating-system override was applied as a sparse patch, so the
replaced system's fields bled through. A storage flat reclassified as a gas
combi (property 728513) kept mains_gas=False, heating category 7, the 2401
storage charge control, a Dual meter and an electric-immersion cylinder — an
incoherent record that gated out the gas-boiler-upgrade Measure and made the
heating Generator read the dwelling as off-gas (offering HHRSH storage).
Extend the ADR-0035 drag-along to gas boilers (Table 4b 102/104/120): the
overlay now sets the whole coherent companion set — mains_gas, gas main fuel,
heating category 2, fanned flue, full modern controls (2106), a single-rate
meter, and hot water from the main system with the cylinder set from the boiler
type (combi → none, regular/CPSU → cylinder). The main_fuel overlay also flips
mains_gas=True for a "mains gas" fuel. Non-off-peak archetypes now drag an
explicit Single meter so a system switch never leaves a stale Dual.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
