FA-92347 / HVAC thermostat control / Member archive

Heating call starts without its differential · case 02

The furnace starts as soon as the room dips below setpoint and short-cycles around it.

Member previewVariant 2 · 3 implementations · 8 checks per implementation

Case contract

Auto heat/cool thermostat sampled once per minute (temps in tenths F). If the cooling setpoint is less than 3.0 F above the heating setpoint it is pushed up to heat_sp + 30 (the heating setpoint wins). Heating starts below heat_sp - 1.0 F and ends at temp >= heat_sp; cooling starts above cool_sp + 1.0 F and ends at temp <= cool_sp. After a heating call ends, cooling may not start until 5 minutes later, and vice versa. Return heat, cool or idle 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 2	`["heat", "idle", "idle", "idle", "idle", "idle", "idle", "idle", "idle", "heat", "heat", "idle", "idle", "idle", "idle", "idle", "idle", "idle"]`	`["idle", "idle", "idle", "idle", "idle", "idle", "idle", "idle", "idle", "idle", "idle", "idle", "cool", "idle", "idle", "idle", "idle", "idle"]`	Failed

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