How to Vent Two Dryers? | Separate Vents For Each Dryer

Vent two dryers by giving each its own independent 4-inch exhaust duct to the outdoors; never route two vented dryers through one shared vent.

Two dryers in one household usually means one laundry room wall that suddenly needs two holes to the outside. The fix for venting two dryers is simpler than most people expect: run each dryer to its own independent 4-inch exhaust duct, and let the outdoors handle the moisture.

Skipping that second hole is tempting when the wall is already crowded, but a shared-vent shortcut is where airflow stalls and lint builds up — the conditions behind most dryer fires.

This article covers why sharing a single vent fails, the duct setup that passes code, and the mistakes that turn a laundry room into a fire hazard.

Can Two Dryers Share One Vent?

For vented dryers, the honest answer is no as a default. Model building code language says dryer exhaust systems “shall be independent of all other systems” and must convey moisture to the outdoors, so sharing one exhaust run between two dryers sits outside the standard path.

Two dryers on one duct means two 230 CFM flows fighting over a single pipe, which stalls airflow, traps lint, and can trip the dryer’s thermal shutdown.

The only real exception is written approval. If a specific dryer model’s installation instructions explicitly allow a shared or listed alternate system, that document wins. Otherwise, treat one vent for two vented dryers as a nonstarter.

Y-diverters exist so two dryers can alternate through one wall opening, but those setups are only acceptable when the manufacturer’s instructions for both machines permit a shared system. If you’re comparing that route, our tested roundup of 4-inch dryer diverters shows what’s out there — treat it as research, not approval, until both manuals sign off.

How To Run Two Dryer Vents Safely

The code-aligned setup is two separate 4-inch runs, and the steps below apply to each dryer identically.

1. Run smooth-walled rigid metal duct from the dryer’s 4-inch outlet toward the outdoors. Flexible foil or plastic duct is the cheap shortcut that fails.
2. Keep the run short. Longer runs are only acceptable when the dryer manufacturer’s installation instructions explicitly allow them.
3. Terminate outdoors with a backdraft damper so cold air and rodents can’t come back in. Never end the vent in an attic, crawlspace, basement, or indoor space.
4. Skip the screen on the termination hood. Screens catch lint and clog the whole run over time.

When both runs are done, test each one alone: you should feel a strong stream of warm air at the outdoor hood and no lint escaping at the joints.

For multiple dryers, the ideal arrangement is always an individual exhaust per dryer. A manifold that collects several dryers into one duct is possible only when it’s sized for all dryers operating at the same time, with airflow velocities held in range and a layout that prevents back pressure from one unit stalling another. Whirlpool adds that any central system should feed each dryer individually with weighted dampers on each branch and periodic lint inspection of the whole duct. That’s an engineered exception, not a DIY weekend project.

Whirlpool’s dryer venting specifications spell out the per-dryer requirements in detail.