What a purge sector is
A rotary energy wheel spins exhaust and supply airstreams through the same matrix, so a small amount of exhaust gas and moisture is inevitably carried into the supply. A purge sector is a slice of the wheel (typically 5-15 degrees) where a portion of the clean supply air is directed backwards through the matrix to flush out residual exhaust before that section re-enters the supply duct.
What it reduces
- Gas carryover: a few percent of exhaust volume can migrate to supply; purge cuts it.
- Moisture carryover: important in humid climates where enthalpy recovery is used.
- Particulate carryover: helps in mildly dirty exhaust.
Limits of purge
Purge lowers but does not eliminate carryover, and it costs a little recovered energy. For genuinely contaminated streams – labs, hospitals – isolation beats purge, so a separated plate or heat pipe is preferred over a wheel.
Frequently asked questions
Does purge waste energy? A small amount, but it protects supply air quality, which is usually worth more.
Is purge the same as bypass? No – bypass diverts flow around the wheel for free cooling; purge cleans the matrix in place.
Need help specifying the right air-to-air heat recovery for your project? Contact the QIYU engineering team – WhatsApp +86 157 5335 5505, or email kuns913@gmail.com.
Frequently Asked Questions
What is the purge sector on a rotary wheel?
A portion of the wheel, often 5 to 15 percent, is purged with supply air to sweep residual exhaust out of the matrix before it re-enters the supply stream, reducing carryover.
Does purge eliminate cross-contamination?
It greatly reduces it but cannot eliminate it entirely; for truly separated streams, such as dirty or contaminated exhaust, a plate or run-around coil is safer.
Frequently Asked Questions
What is the purge sector on a rotary wheel?
A portion of the wheel, often 5 to 15 percent, is purged with supply air to sweep residual exhaust out of the matrix before it re-enters the supply stream, reducing carryover.
Does purge eliminate cross-contamination?
It greatly reduces it but cannot eliminate it entirely; for truly separated streams, such as dirty or contaminated exhaust, a plate or run-around coil is safer.
Specify the right heat exchanger
Our engineers size the core to your airflow, temperature and pressure-drop budget, and select plate, rotary or heat-pipe recovery by application. Read the heat exchanger guide or contact us for a specification.
Related products
Plate, wheel or pipe recovery for HVAC and ventilation.
Stationary, high-surface-area cores for air and liquid.
High-effectiveness energy recovery for large airflows.
Passive, fully separated streams for clean applications.