Assessment & Optimization11 / 13
Common Faults & Failures
Stuck dampers, failed sensors, thermostat drift, and control errors.
9 min read · Jacob Willis, Net Zero Lead · Last reviewed July 2026
The same problems crop up in HVAC systems across buildings. Knowing the patterns, and how they manifest, helps you diagnose and fix them quickly.
In this lesson
- 01Symptom: "The building is always too hot or cold"
- 02Symptom: "Heating energy is much higher than it should be"
- 03Symptom: "Cooling energy is much higher than it should be"
- 04Symptom: "Different zones have very different temperatures"
- 05Symptom: "Fan noise increased"
- 06Symptom: "Condensation on windows / mould in bathrooms"
- 07A practical repair hierarchy
- 08Sources and further reading