Heat Exchanger Selector: Pick the Right Air-to-Air Core

Specifiers freeze when they see plate, rotary, cross-flow and heat-pipe side by side. The truth is that a heat exchanger selector is just five questions — answer them and the right core is almost forced. This is the same logic as our 10-point checklist, compressed into a decision you can run on one screen.

Q1 — What is the actual duty?

Airflow per stream (m³/h), inlet temperatures and annual hours. This sizes the core (use the sizing tool) and sets the recoverable energy (use the savings tool). No duty, no selection — stop here until you have it.

Q2 — What is in the exhaust?

This single question eliminates options faster than any other.

Q3 — Cold climate?

If the exhaust can drop below 0°C while still humid, you need frost control — preheat, exhaust bypass or a defrosting wheel. Run the frost calculator to set the threshold; read frost control.

Q4 — Must you move moisture?

Hot-humid summers and high internal loads call for an ERV (moisture transfer); dry heating climates want an HRV (heat only). The full split is in ERV vs HRV and enthalpy vs sensible.

Q5 — Can the streams mix?

If supply and exhaust must never cross (labs, some process lines), a run-around coil or heat pipe keeps them separate. A rotary wheel carries a little carryover by design.

Worked example

A plant exhausts 8,000 m³/h of 30°C, slightly greasy air, 6,000 h/yr, outdoor winter −10°C. Q2 says washable; Q3 says frost control needed; Q4 says heat-only HRV is fine (dry climate); Q5 allows mixing. Result: a coated counterflow plate HRV with exhaust bypass and a washable core, ~80% effectiveness — modelled at roughly 2-year payback with the payback tool.

The selector in one line

Clean duty → plate; dirty → washable; corrosive → stainless; humid → ERV; cold → frost control; no-mix → heat pipe / run-around. Everything else is sizing and certification.