What happens
The installed ventilation setup does not deliver the intended supply/exhaust balance or outdoor-air routing.
Typical symptoms
Drafts, unwanted pressure effects or uneven ventilation after installation.
Checks that distinguish this cause
Compare actual module configuration, connections and measured flows with the ventilation design and module manual. Check bypass or operating-mode settings where provided.
What can look similar
Building exhaust equipment or envelope leakage can change pressure even with correctly balanced ventilation.
Repair direction
Correct the established installation or balancing defect using the approved design.
Verify the repair
Document ventilation flows and verify representative building operation.
Equipment-specific limits
Not every all-in-one unit contains an ERV. Cooling airflow and ventilation airflow are different measurements; use the module’s filtration, balancing and maintenance requirements.
Practice this diagnosis
This cause is a reference topic; it does not yet have a dedicated simulated call. Browse the practice board.
References and applicability
Original HVACSim explanations with manufacturer and instrument-maker references for further reading. These resources support the subject; their model-specific examples are not specifications for every system.
- INNOVA (formerly Ephoca): AIO technical resourcesChoose cabinet style, generation and accessories. Installation, maintenance and troubleshooting documents are separate.
Editorial review: 2026-09-29. Verify the current manual for the installed model.