Overview
This lecture explains the preferred installation arrangements for a dehumidifier in HVAC systems, focusing on return-to-return versus return-to-supply configurations and their implications.
Preferred Installation: Return-to-Return
- Preferred installation is "return-to-return," where both the air handler and dehumidifier connect to return air ducts.
- Works with upflow (basement, closet, garage) or horizontal flow (attic) air handler orientations.
- Fans inside the air handler and dehumidifier operate more efficiently in series, reducing blower load.
- Constant CFM (cubic feet per minute) is maintained, and fan pressures can enhance each other.
- Warmer dehumidified air mixes better with return air, leading to less temperature variance entering the air handler.
- Air can be cooled and further dehumidified before being supplied to the space.
Alternative Installation: Return-to-Supply
- "Return-to-supply" is used when space prevents proper return-to-return installation (e.g., not enough clearance).
- In this setup, blowers can conflict, causing increased load and possible airflow issues.
- There are requirements for airflow pressure range to avoid fans fighting each other.
- Mixing warmer dehumidified air into the cold supply can slightly impact cooling performance.
- Acceptable but less efficient and potentially harder on equipment.
Key Terms & Definitions
- Return Air Duct — Ductwork carrying air from the space back to the air handler or HVAC equipment.
- Supply Air Duct — Ductwork delivering conditioned air from the HVAC system into the space.
- Air Handler — Component that moves air through heating and cooling systems.
- Dehumidifier — Device that removes moisture from the air; in this context, installed with HVAC systems.
- CFM (Cubic Feet per Minute) — Measurement of air volume moved per minute.
Action Items / Next Steps
- Review the installation diagram for return-to-return and return-to-supply configurations.
- Prepare any questions about installation preferences for clarification.