Honeywell Home MARD18 Modulating Automatic Round Damper Installation Guide

Modulating Automatic Round
Damper
(MARD)

INSTALLATION INSTRUCTIONS

APPLICATION

The Modulating Automatic Round Damper is a round damper with a 24-Vac, floating-control type modulating motor for bypass and zone damper control. It is constructed of 22-gauge galvanized steel and has male (crimped) and female (uncrimped) ends to connect to any rigid or flexible round duct. It is available in 5, 6, 7, 8, 9, 10, 12, 14, 16, 18 inch diameter sizes. The motor timing is 90 seconds open to closed.
The MARD is used for bypass control when connected to the Static Pressure Switch (SPC). Although it can be used on any bypass application, it is recommended for systems larger than 2000 cm. The MARD can also be used as a zone control damper connected to a zone control panel.

INSTALLATION

Before Installing this Product…

1.  Read all instructions before installing this product. Failure to follow the instructions can damage the product or cause a hazardous condition.
2. Check the ratings given in the instructions and on the product to make sure the product is suitable for your application.
3. Installer must be a trained, experienced service technician.
4. Install the product in an area that is easily accessible for checkout and service.
5. After completing the installation, use these instructions to check out the product operation.

Selecting Damper Size

1.  To size the bypass damper, subtract the smallest zone cfm from the total systemcfm. The remainder is the amount of air that needs to be bypassed.
2.  Calculate the bypass damper size using this com and a friction loss of .25 in. on a duct calculator or see Table 1.
3. If used as a zone damper, size it the same diameter as the duct.

Table 1. MARD Size.

a Use this table only to size bypass dampers; for zone damper sizing, use a duct calculator.

Selecting Damper Location
The damper can be installed horizontally or vertically.
Orient the damper so the motor is located on the side or top of the damper, not on the bottom of the damper.

Mounting the Damper

1. Install a duct collar into the duct or plenum upstream of any zone dampers. It is preferable to place it as far as practical from the air handler.
2.  Slide the damper onto the duct collar.
3.  Secure with sheet metal screws (not provided).
4.  Run duct from the other end of the damper to the return duct.

WIRING

The ML6161B2024 motor has a 35 in.-lb, 3 VA, 24 Vac, 50/60 cycle rating. Protect the HVAC equipment from freeze-up and from tripping the high limit with a
discharge air temperature sensor as follows:

•  C7735A1000 on the TrueZONE Zone Panels
•  C7835A1009 on Networked Zoning (obsolete)
•  FPC and T6031A1276 (SPBT) on older zone control boards.
  Multiple dampers can be connected in parallel. See Fig. 1-Fig. 3. See the SPC literature for additional connection information.

Settings/Adjustment

See the SPC literature for configuration instructions.

CHECKOUT

To check out the MARD:

1. With 24 Vac applied to the M1 (common) and M4 (open) terminals, observe that the motor powers the MARD to the open position.
2. With 24 Vac applied to the M1 (common) and M6 (close) terminals, observe that the motor powers the MARD to the closed position.

Resideo Technologies, Inc.
1985 Douglas Drive North, Golden Valley, MN 55422
1-800-468-1502
69-1551—02 M.S. Rev. 01-21 | Printed in the United States

www.resideo.com

© 2020 Resideo Technologies, Inc. All rights reserved.
The Honeywell Home trademark is used under license from Honeywell International, Inc. This product is manufactured by Resideo Technologies, Inc. and its affiliates.

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