Heat-Pump Thermostat O/B Setting: Reversing-Valve Logic
Set heat-pump O/B reversing-valve logic from manufacturer data, then distinguish a configuration error from valve, wiring and refrigeration faults safely.
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Mini-Split Line Length and Additional Refrigerant Charge
Check mini-split line-length limits, factory-charge coverage, added refrigerant and elevation rules using exact model installation data and weighed records.
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Attic Duct Leakage: Separating Air Loss From Heat Gain
Learn how attic duct leakage differs from insulation heat gain, which tests identify each problem and why cold register air does not prove intact delivery.
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Mini-Split Condensate Drain Problems: Leaks, Pumps, and Slope
Trace mini-split condensate leaks through pan, hose, slope, pump and wall penetration checks while separating drainage faults from coil icing and humidity.
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Supply-Side vs Return-Side Duct Leakage: Why Location Matters
Compare supply-side and return-side duct leakage, including operating pressure direction, comfort effects and the measurements needed to locate each path.
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Thermostat C-Wire Requirements: Power Symptoms and Safe Checks
Learn what a thermostat C-wire does, which power symptoms suggest a circuit problem and why adapters, unused conductors and compatibility require wiring.
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Pressure Pan Testing: Finding Duct Connections to Outdoors
Learn how pressure-pan testing screens individual registers for duct connections to outdoors, what a high reading suggests and why it is not a CFM test.
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Thermostat Remote Sensor Averaging: Comfort and Setup Limits
Understand thermostat remote-sensor averaging, occupancy selection, schedules and placement limits so one comfortable room does not hide another room’s load.
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Mini-Split Indoor Head Icing: Airflow, Load, and Refrigerant Boundaries
Diagnose ice on a mini-split indoor head by checking airflow, operating conditions and drainage before technician-only sensor and refrigerant measurements.
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Single-Stage vs Multi-Stage Thermostat Control: What Changes
Compare single-stage and multi-stage thermostat control, including terminals, staging logic, equipment-board timers, comfort effects and commissioning checks.