Johnson Controls M9108-GGA-2 Proportional Damper Actuator

M9108-GGA-2 proportional damper actuator, 70 lb·in, 24 V

The Johnson Controls M9108-GGA-2 is a direct-mount electric actuator for HVAC dampers and valves that need modulating control rather than simple open/close. It belongs to the M9108 series of non-spring-return actuators, delivers up to 70 lb·in (8 N·m) of running torque, and runs on 24 VAC or 24 VDC. Seven Star LLC supplies the M9108-GGA-2 in Oman and the GCC as an independent supplier in Muscat.

Reading the code against the manufacturer’s ordering table: the series is M9108, the GG pair identifies the 70 lb·in proportional version with fixed zero and span, the final letter A means 0 to 10 VDC position feedback and no auxiliary switches, and -2 is the revision suffix. The sister model M9108-GGC-2 adds two SPDT auxiliary switches, while M9108-HGA-2 keeps the feedback but adds adjustable zero and span.

M9108-GGA-2 technical specifications

How the M9108-GGA-2 positions a damper

Inside the housing a DC motor drives a gear train to the output coupler. A control signal from the building controller is compared with the position feedback, and the actuator drives until the two agree. Because the actuator accepts either a voltage or a 4 to 20 mA current signal, the same M9108-GGA-2 can follow the output of most DDC controllers and analogue thermostats once the jumpers are set.

Electronic stall detection monitors the motor through the whole stroke and shuts it down if the damper jams, which protects the gear train. Noise filtering on the input signal prevents the actuator from hunting on a noisy line. A spring-loaded gear release on the cover lets a technician disengage the gears and turn the coupler by hand when the unit is unpowered.

Where the M9108-GGA-2 fits and related models

This actuator suits return-air, exhaust, face-and-bypass and variable-volume fan blade applications in comfort-cooling and ventilation systems. It is not a safety device and the manufacturer states it is not meant for explosive atmospheres or corrosive environments. Where a damper must close on loss of power, for example fresh-air dampers in cold climates, the manufacturer recommends a spring-return actuator from the M9206 or M9216 families instead.

Within the M9108 range the siblings are M9108-GGC-2 (two auxiliary switches plus feedback), M9108-HGA-2 and M9108-HGC-2 (adjustable zero and span). Accessories listed in the same bulletin include the M9000-150 and M9000-151 linkage kits for remote mounting, the M9000-154 jackshaft coupler for 1 in. shafts, the M9000-155 manual handle, the M9000-160 replacement anti-rotation bracket, the M9000-200 commissioning tool and the M9000-300 weather shield enclosure.

Selecting and ordering the M9108-GGA-2

• Confirm the damper torque requirement is within 70 lb·in for a single actuator; tandem operation is not supported.
• Check the shaft: round up to 3/4 in. or square up to 5/8 in. fits directly, other sizes need a coupler kit.
• Verify that the controller output is 0 to 10 V, 0 to 20 V or 4 to 20 mA and that the required rotation direction can be set by jumper.
• Decide whether auxiliary switches (GGC) or adjustable zero and span (HGA) are needed; if not, the GGA version is sufficient.
• Allow for the 7.5 VA draw per actuator when sizing the 24 V Class 2 transformer.
• Check ambient limits of -20 to 50°C and the NEMA 2 / IP42 rating against the mounting location.

Installation and commissioning of the M9108-GGA-2

The actuator can be mounted in any orientation, directly on the shaft with the supplied U-bolt clamp and anti-rotation bracket. Set the rotation angle first by repositioning the removable coupler, then use the jumpers to choose action direction, input range and calibration mode. The cover carries a dual scale marked in 10-degree steps so the end positions can be checked visually.

During commissioning, drive the controller from minimum to maximum and confirm that the damper blades reach full closed and full open at the expected signal values, and that the feedback voltage tracks the position. The M9000-200 commissioning tool is helpful for simulating a signal without the controller. In service there is little to maintain beyond checking the clamp, wiring terminals and keeping the housing free of dust.

Typical applications in Oman and the GCC

In the Gulf, large share of building energy goes to cooling, so modulating damper actuators such as the M9108-GGA-2 are used in air-handling units, fresh-air mixing boxes and exhaust systems of hospitals, malls, hotels, data rooms and plant control buildings. Dust, high summer temperatures and humidity make it important to keep the unit inside the supplied ambient range and to shade actuators on outdoor ducting, optionally with the weather shield enclosure. Industrial sites in oil and gas, power and desalination use the same actuators on non-hazardous ventilation of control rooms and electrical rooms.

M9108 family comparison

Information to send with a M9108-GGA-2 RFQ

• Quantity and the exact model code, including the -2 suffix.
• Damper make, shaft shape and size.
• Controller output type and range.
• Required accessories such as linkage kits, manual handle or weather shield.
• Site location and mounting conditions (indoor, outdoor, dust exposure).
• Delivery destination in Oman or the GCC.

Documents and quotation

Send the part number with your enquiry and we will confirm the technical documents available for this item.

Send us the part number M9108-GGA-2 with your quantity and delivery location and Seven Star LLC will reply with a quotation and confirm lead time.