The ASHP bundle is a fixed whole-system end-state (confirmed: always the same
contractor cylinder), so the hot-water arrangement is fixed too. The overlay now
sets water_heating_code=901 ("from main system") absolutely, so a combi (909/611)
or electric (903/908) before is reset to HW-from-the-heat-pump — previously the
overlay relied on the before already lodging 901 (true for boiler-1, not in
general). No-op for the boiler-1 pin (stays 1e-4). Cascade pins for combi /
electric-with-cylinder befores await example certs. ADR-0024.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Adds the air-source heat-pump Option to the competing "Heating & Hot Water"
bundles. Its overlay is the absolute heat-pump end-state (fixed representative
PCDB index 101413 + category 4 + control 2210 + HWP cylinder + single meter +
off mains gas), pinned against the relodged after-cert next slice. Eligibility
is physical/planning only (ADR-0024, research-grounded): any non-flat
house/bungalow, not listed/heritage (PlanningRestrictions.blocks_internal —
conservation is offered with a caveat, not excluded), not already a heat pump;
floor area / built form / fuel / fabric are deliberately not gates. recommend_
heating gains a restrictions param (defaulted). An already-HHR electric house
now correctly gets ASHP as a better end-state.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
The same absolute-target HHR overlay reproduces the common relodged after from
two different base systems (existing electric storage; "no system present"
electric) — proving the bundle is a true whole-system end-state. Closes one
named gap the pin surfaced: the relodged HHR cylinder lodges
cylinder_thermostat='Y', so HeatingOverlay + _fold_heating + the HHRSH overlay
gain cylinder_thermostat (ΔSAP 0.065 -> <1e-4). ADR-0024.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
The heating Recommendation Generator (HHRSH first). Emits one "Heating & Hot
Water" Recommendation whose competing whole-system bundles the Optimiser picks
from; this slice builds the high-heat-retention storage Option. Its overlay is
the absolute HHR end-state (Table 4a code 409 + control 2404 + dual off-peak
meter + off-peak electric cylinder), pinned against the relodged after-cert in
the next slice. Eligibility translates legacy is_high_heat_retention_valid to
structured predicates (electric or off-gas main, not already HHR/heat-pump).
mains_gas and the heat emitter are unchanged by the measure, so unset. ADR-0024.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
