30012 – DAMPER (12″ W/ KEY)

A duct damper lets you control how much air flows through a specific duct run. If one room is too hot or too cold, adjusting the damper in that run can help balance temperatures throughout the house. The key handle lets you open, close, or partially restrict the 12-inch duct.

Specs: 12″ round, galvanized steel, key-operated handle, 28-gauge

Replaces: 30012, 91512-MM, SHMD2H12

Fits: Any 12″ round duct run — installs inline between duct sections

In stock at Open To Public HVAC Parts in Dallas. We test parts at the counter before you buy. Call or text (214) 340-9421.

Specs

• TypeManual volume damper
• Duct size12" round
• ControlExternal key handle, lockable
• PositionInstall at the branch takeoff, not at the register

Cross-reference numbers

This part replaces the following OEM and aftermarket numbers:

• 30012
• 91512-MM

Not sure if your number matches? Call (214) 340-9421 or bring the old part in — bench-testing is free.

Fits these models

• MASTERFLOW12DAMPER
• MASTERFLOW12DUCTDAMPER
• STANDARD12HVACVOLUMEDAMPER

What does the key do?

The key is the external handle that lets you set the blade position from outside the duct and lock it there. Set it once during balancing and leave it - it is not a season-to-season control.

Where does a damper go?

In the branch run, close to the trunk takeoff, not up at the register. Balancing at the takeoff moves air to the rooms that need it. Closing it at the register just makes noise at the grille.

Can I use dampers to shut off rooms I do not use?

Balancing, yes. Shutting rooms off, carefully. Closing several branches raises static pressure across the whole system, which can freeze a coil or push the blower out of its range. A damper is for trimming a room that runs too hot or too cold, not for closing half the house.

How do I know which way is open?

The handle lines up with the blade. Handle parallel to the duct run is open, across it is closed. Mark it once you have it balanced so nobody guesses later.

Do you stock all the sizes?

We keep 5 inch through 16 inch on the shelf at 10226 Plano Rd, Suite 104 in Dallas.