FA-92367 / HVAC thermostat control / Member archive

Stage-2 time upstage counts stage-1 runtime from earlier cycles · case 02

A new heating cycle brings on the second stage almost immediately because previous cycles' runtime is carried over.

Member previewVariant 2 · 3 implementations · 8 checks per implementation

Case contract

Two-stage furnace thermostat sampled per minute. Stage 1 starts at temp <= setpoint - 1.0 F and ends at temp >= setpoint. Stage 2 requires stage 1 and starts either on droop (temp <= setpoint - 3.0 F) or after stage 1 has been on for more than 10 samples of the current cycle while still below setpoint - 0.5 F; it ends at temp >= setpoint - 0.3 F or when stage 1 ends, and cannot restart within 3 minutes of ending. Return [stage1, stage2] per minute.

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: scenario 27	`[[false, false], [false, false], [true, false], [true, false], [true, false], [true, false], [true, false], [true, false], [true, false], [true, true], [true, true], [true, true], [true, true], [true, true], [true, true], [true, true], [true, true], [true, true], [true, true], [true, false], [true, false], [true, false], [true, true], [true, true], [false, false], [false, false], [false, false], [true, true], [true, false]]`	`[[false, false], [false, false], [true, false], [true, false], [true, false], [true, false], [true, false], [true, false], [true, false], [true, true], [true, true], [true, true], [true, true], [true, true], [true, true], [true, true], [true, true], [true, true], [true, true], [true, false], [true, false], [true, false], [true, true], [true, true], [false, false], [false, false], [false, false], [true, false], [true, false]]`	Failed

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