Three steps, one number to look up, no pressure-drop math. Get a planning screen for whether your HRV or ERV can push air through a particle-and-carbon bank — before you build anything.
Adding filtration adds resistance and normally moves the fan/system operating point toward lower airflow. The exact response depends on the fan and its controls. The main design concern is whether enough outdoor air remains available at the chosen smoke-mode setting.
So the real question isn't simply "will this damage my HRV or ERV?" It's "is the target filtered airflow plausible given this unit's fan curve and the filter bank's resistance?" That's what the steps below screen.
Open your HRV/ERV's spec sheet and find its performance table — airflow (CFM) vs. external static pressure (in. w.c.). The highest value in the static column is useful only as a rough pre-screen. The meaningful check is the static pressure the unit can deliver at your chosen smoke-mode airflow, after accounting for the existing duct system.
Full toolkit — HEPA + carbon is on the table.
Units like the RenewAire EV90, and many Fantech / Zehnder models. Enough headroom for a true single-pass HEPA-and-carbon bank at a useful airflow.
MERV-13 comfortably; HEPA with care.
The two-MERV-13 build runs easily. HEPA is doable if you run reduced smoke-mode airflow and oversize the carbon face. Check it in Step 3.
MERV-13 build, at reduced flow. HEPA unlikely.
Typical of many residential units (e.g., Broan/Panasonic class rated near 0.2"). Still very worth doing — a MERV-13 intake plus indoor recirculation beats no filtration by a wide margin.
Can't find the table? Search your model number plus "performance data" or "specification sheet." The curve you want plots CFM against external static pressure — the same shape as a fan curve, sloping down to the right.
You generally do not need to run the unit at its full ventilation rate during a smoke event, but the correct smoke-mode airflow depends on the building and ventilation requirements. Lower airflow reduces filter pressure drop, which is what makes the bank feasible on modest units.
A planning starting point used in this guide. Use a CO₂ monitor as a ventilation indicator and increase filtered airflow if CO₂ rises substantially above your normal occupied level. Pick the airflow you'll test against in Step 3.
Choose your build and smoke-mode airflow. Then read one number off your unit's table — the static pressure it delivers at that airflow — and enter it. The checker does the rest.
This planning screen models a single MERV-13 final stage. If you build two MERV-13 filters in series, add the second filter’s pressure drop from its manufacturer data or from measurement.
Fill in your unit's static pressure above to see whether it clears the bank.
RenewAire's published performance table shows 0.40" at 68 CFM and 0.50" at 53 CFM in the example used here. Say you target 60 CFM with the HEPA build (modeled bank resistance 0.27") and estimate 0.10" for everyday ducts. This is a planning calculation; the actual operating point should be verified after installation.
Interpolating between those points gives roughly 0.45" available static at ~60 CFM. The planning headroom is 0.45 − 0.27 − 0.10 = +0.08", so the target passes this simplified screen. That does not prove the final operating point will be exactly 60 CFM; verify the installed airflow and pressure drop. A 0.2"-class unit, by contrast, would have little or no margin for this example bank.