/ Field knowledge · IMC 801.14
A fan symbol is not a pressure boundary.
A power exhauster turns a passive vent into a pressure-managed assembly. Connect the appliance on the inlet side. Everything on the discharge side has to be listed for positive pressure. A fan symbol dropped into a natural-draft detail is not that review.
Educational 2024 International Mechanical Code (IMC) 801.14 from Daily Code Talk. Confirm the adopted edition. Distinct from positive-pressure listing (801.9) and mechanical-draft interlocks (804.3). This is not an exhauster selection. Packet: 801.14 PDF · ES.
- Appliance connections to a chimney or vent equipped with a power exhauster are made on the inlet side of the exhauster.
- Joints and piping on the positive-pressure side must be listed for positive-pressure applications as specified by the exhauster manufacturer’s installation instructions.
- Do not treat standard vent joints as acceptable for positive pressure without listing evidence. Do not treat the exhauster as an electrical device only — it changes vent-system pressure and leakage risk.
On the set: flow arrow, inlet and discharge labeled, positive-pressure boundary, listed downstream assembly, supports, access, condensate, power, and the manufacturer-required safety sequence. A reviewer should trace appliance → exhauster inlet → discharge → listed positive-pressure assembly → termination in one pass.
Fan symbol, no upstream vs downstream
Standard vent materials continue through the positive-pressure side. Manufacturer instructions missing. Flue-gas leakage, carbon monoxide, corrosion, condensate, nuisance shutdowns, failed inspection. Escalate natural-draft appliances proposed downstream of a mechanical flue exhauster, and existing-chimney reuse.
Source: Daily Code Talk — IMC 801.14 · tool: Inlet-side screen · sizing: 804.3.6–804.3.7 · 801.9: positive pressure · 804.3: interlocks · termination: 804.3.3–804.3.4.
What to send
Exhauster cut sheet, a sketch or photo showing which side the appliance connects, and whether the discharge piping is listed for positive pressure.
If a power venter was added to an existing chimney
Send the photo and the cut sheet. MasterBuild will say whether 801.14 still has the appliance on the wrong side — or 801.9 still has no positive-pressure listing on the discharge.
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. This page is 2024 IMC 801.14 education from Daily Code Talk — not an exhauster specification. This page is not legal advice.