Honeywell Home ZD20X10TZ/U 20 in x 10 in Parallel Blade Damper

The Honeywell Home ZD20X10TZ/U is a 20 in. x 10 in. motorized zone damper for forced-air systems. It installs in the branch duct serving one zone and opens or closes that branch on a call from the zone panel, so a single furnace or air handler can hold different temperatures in different parts of a building.

Power close, spring open. The 24 Vac motor drives the blades closed when it is energized, and a spring returns them open when power is removed. That makes the ZD fail-safe normally open: if the panel loses power or a wire opens, the branch stays open and the zone keeps getting air instead of being shut off. The ZD cannot be field-converted to power open — for fresh-air applications the round EARD is the power-open part, and the round ARD converts with an M847D-VENT actuator.

Sizing and orientation. Order by the duct opening, not by the room. This is the 20 in. x 10 in. size, and the actuator mounts on the 10 in. side, because Resideo always puts it on the second dimension — a ZD10X20TZ is the same opening with the motor on the 20 in. side. Every ZD is built 5/32 in. under its listed size so it drops into nominal duct, and all ZD models are 4 in. thick. The damper can be installed in any orientation, with the mounting side on the bottom or the side of the duct.

Electrical and performance. 24 Vac, 60 Hz, 8 VA. Two-wire hookup on push terminals; solid wire is recommended rather than stranded. A third wire, option M4, drives an LED open light. Nominal rotation is 90 degrees with a minimum 71 in.-oz. (500 mN·m) output torque. At 77 °F the motor drives closed in about 30 seconds and the spring return takes about 10 seconds. Ambient rating is 40 to 140 °F. Leakage is under 1% at 1/2 in. wc, maximum static pressure is 1 in. wc, and pressure drop wide open is 0.0329 in. wc at 800 ft/min.

Build. Extruded aluminum frame and blades, all-metal drive train gears and high-temperature outer plastic, with a taping flange and a non-interfering set screw. The parallel blade geometry is what keeps leakage low. A front-facing display with an LED shows open and closed at a glance, and adjustable closed-position range stops let you leave a minimum bleed through the branch instead of shutting it dead.

Replacement actuator: M847D-ZONE. Works with TrueZONE panels and other 24 Vac electronic zoning systems.

• Brand: Honeywell Home
• Manufacturer Part #: ZD20X10TZ/U
• Category: Zone Dampers