/ Field knowledge · IMC 502.14
A ceiling fan over a running engine is not source capture.
A ceiling fan over a running engine is not source capture. IMC 502.14: areas where vehicles operate need IMC 403 ventilation plus a source-capture connection on the tailpipe where engines run in place. Exceptions are narrow: electric-vehicle-only spaces, one- and two-family dwellings, or spaces where engines run only long enough to move vehicles in and out. A CO sensor on the wall does not replace the hose on the tailpipe.
Educational 2024 International Mechanical Code (IMC) 502.14 from Daily Code Talk (same post as 502.11–502.20). Confirm the adopted edition. Distinct from 404 enclosed-garage ventilation and 502.16 gaseous-fuel repair. This is not a shop design.
- Engines that idle, diagnose, or run on a dyno in place: source-capture connected to the tailpipe, plus the room ventilation in IMC 403.
- Exceptions: EV-only; one- and two-family dwellings; engines that run only to move the vehicle in or out.
- Do not call a 404 garage CO system “source capture.” Do not dump the hose into the return plenum.
- Related 502.13–502.15: public garages exhaust continuously or per IMC 404 + 403. Where Class I liquids or LP-gas can reach basements or pits, exhaust so flammable vapor cannot build up.
On the set: show the hose drops or tailpipe adapters, which bays they serve, and that discharge is outdoors. If the shop is EV-only, say so on the drawings — that is the exception, not a silent assumption.
Four service bays, one wall fan, no hoses
Idling for diagnostics is “run in place.” The exception is move-in / move-out, not a 20-minute scan tool session. CNG/hydrogen bays still follow 502.16 (low inlets, high outlets) on top of this.
Source: Daily Code Talk — IMC 502.11–502.20 · tool: Run-in-place screen · garage: 404 · CNG: 502.16 · spray: 502.7.
What to send
How many bays idle engines in place, whether any hose drops exist, fuel type (gasoline / diesel / CNG / hydrogen / EV-only), and photos of the shop ceiling.
If the shop idles engines with no tailpipe hose
Send the bay count and a photo. Masterbuild will say whether 502.14 still has no source capture — or 502.14 still treats a wall fan as the tailpipe.
Send Project Background+1 (786) 398-6940 · osmany.portal@masterbuildconsulting.com
Masterbuild provides engineering services under a written scope. Nothing on this page is project-specific engineering advice, a code interpretation for your project, or a representation about permit approval. Confirm the adopted edition. Source-capture on tailpipes where engines run in place, and the EV-only / dwelling / move-in-out exceptions, are 2024 IMC 502.14 education from Daily Code Talk — not a shop design and not a cfm. This page is not legal advice.