Why the terms matter
Understanding the language of heat recovery helps buyers specify the right equipment and compare quotations accurately. This glossary covers the terms most often encountered when sourcing air-to-air heat exchangers and plate recovery cores.
Effectiveness and efficiency
Effectiveness, also called recovery efficiency, is the percentage of available heat moved from the exhaust stream to the supply stream. A higher number means more energy recovered, but it usually comes with a larger core and higher pressure drop, so the figure must be read together with the operating conditions, not in isolation.
Sensible vs enthalpy recovery
Sensible recovery transfers only heat, while enthalpy, or total-energy, recovery also transfers moisture. A sensible plate core keeps the two air streams fully separated; an enthalpy plate uses a hygroscopic surface to move both heat and humidity. For hygienic or contaminated exhaust, a sensible plate is preferred because no moisture or contaminant crosses over.
Flow geometry
Crossflow and counterflow describe the relative direction of the two air streams. In crossflow the streams meet at right angles, giving a compact shape; in counterflow they move in opposite directions, which can reach higher effectiveness for the same size. Both keep the streams isolated, unlike a rotating wheel that shares one moving medium between them.
Other key figures
NTU, or number of transfer units, is a dimensionless measure of a core's heat-transfer capacity; it rises with larger area and better conductivity. Face velocity is the air speed across the core face, pressure drop is the fan energy needed to push air through, and fouling factor describes how deposits reduce performance over time. Knowing these terms lets a buyer move from vague "efficient core" claims to verifiable specifications.
Explore more
- Industry articles on heat recovery
- ERV vs HRV plate cores for Passive House and NZEB
- High-temperature heat exchanger materials
Key takeaway
When reviewing a quotation or a core datasheet, keep these terms at hand so marketing language becomes comparable numbers. Open this glossary alongside the supplier's submittal, and ask for the specific value behind any vague claim rather than accepting a single headline percentage.