FA-92618 / HVAC thermostat control / Member archive

Frost-protection limit drops below its 15% floor · case 03

In extreme cold the humidifier is locked out entirely.

Member previewVariant 3 · 3 implementations · 8 checks per implementation

Case contract

Thermostat humidity functions per sample; samples are [temp tenths F, indoor RH %, outdoor whole F]. Dehumidify-by-overcooling turns on when RH > rh_sp + 5 and off when RH <= rh_sp; while on, the effective cooling setpoint is lowered by min(max_overcool, (RH - rh_sp) * 5) tenths. Cooling starts above effective + 1.0 F and ends at <= effective. Humidifier: allowed RH = 40 + floor((outdoor - 20) / 10) * 5 clamped to 15..45; target = min(hum_sp, allowed); it is off when outdoor >= 50, otherwise starts below target - 3 and stops at >= target. Return [cooling, effective_sp, humidifier].

Why this case matters

Residential and light-commercial thermostats make these decisions sample by sample; each defect changes equipment calls in a way that shows up as short cycling, comfort complaints or equipment stress.

One recorded failure

Sample boundary fixture

This sample comes from the broken implementation of a controlled reproducer.

Boundary fixture	Actual	Expected	Outcome
regression: frost limit steps	`[[false, 750, true], [false, 750, true], [false, 750, true], [false, 750, false], [false, 750, false], [false, 750, false]]`	`[[false, 750, true], [false, 750, true], [false, 750, true], [false, 750, false], [false, 750, true], [false, 750, false]]`	Failed

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