Result
Preliminary calculation: This tool is for quick sizing and information. In real projects, load calculation, selection and commissioning require engineering calculations and a site survey. Results are approximate values.
Formulas
ε = (T_supply − T_outdoor) / (T_exhaust − T_outdoor)Q_recovered = 0.335 × V̇_fresh × (T_supply − T_outdoor)Plate cross-flow, counterflow or rotary wheel recovery units operate in different efficiency ranges; the exact efficiency depends on manufacturer data, airflow and pressure loss. As the heat exchanger surface is enlarged to increase efficiency, the fan pressure loss also increases.
- The increase in fan energy reduces the net gain; check it with the fan power tool
- In cold climates, icing and condensate drainage should be considered in the design
- There is a risk of cross-contamination in a dirty or leaking heat exchanger
Frequently asked questions
What should the recovery efficiency be?
It varies by unit and application. What matters is the efficiency documented in the manufacturer's data for the selected unit, and the increase in fan energy.
Why is exhaust flow entered separately?
If the exhaust flow differs from the fresh air flow, the exhaust outlet temperature changes; the risk of icing depends on this value.
Is there moisture recovery too?
Enthalpy exchangers (rotary moisture-permeable wheels, etc.) can transfer moisture too. This tool calculates sensible heat only.