14URD – ZONE DAMPER MOTOR ASSEMBLY

Round 14 in. zone damper assembly with a 24 VAC three-wire power-open/power-closed actuator, used in zoned duct systems to open and close a branch run on a call from the zone panel. Published as a single-blade round zone damper with a UL listed MA-ND5 actuator, nylon bearings and ThermoTuff drive shafts.

Specifications published by the manufacturer. Source: manufacturer documentation.

Specs

• TypeRound zone damper, single blade
• Duct diameter14 in.
• Actuator3-wire power open / power closed, UL listed MA-ND5
• Supply voltage24 VAC
• Power consumption1.5 VA
• Rated airflow1000 CFM
• Pressure drop at rated airflow0.1 in. W.C.
• Static pressure differential1.5 in. W.C.
• Sleeve length16 in.

Only one zone quit working. Is the panel bad?

Usually not. Go to the damper first. Call that zone, then watch the motor and check for 24 volts at it. Most panels have a light per zone, so if the light comes on and the blade does not move, the panel did its part. Stuck blades and dead damper motors outnumber failed panels by a wide margin, especially on attic duct in Dallas where those motors sit in 150 degree heat all summer.

Does the zone panel need its own transformer?

Yes, a dedicated one. The furnace transformer is not sized to run a panel plus powered dampers on top of the equipment's own load. Honeywell TrueZONE panels call for a 40VA class transformer, or the high temperature 50VA version for attic mounting, which in DFW is the one to buy. Do not tie the panel to the furnace transformer to save a part.

Do I need a bypass damper?

Depends on the blower. A single-stage PSC system that can end up with one small zone calling needs somewhere for the air to go, meaning a bypass with static pressure control or a sized dump zone. With a variable speed blower a bypass is often the wrong answer, because it recirculates supply air and drives coil temperature down while the motor already ramps to hold airflow. Size the smallest zone for enough CFM instead.

Can I add a zone to an existing panel?

Only up to what the panel supports. A three-zone panel is three zones, and going past it means a larger panel or a slave board. The bigger question is whether the equipment can live with the smallest zone. Zoning does not create capacity. If that zone cannot take a fair share of the airflow, you will trip limits in heating and freeze the coil in cooling regardless of the panel.