Quest DEH 3000R Wall Mounted Humistat with Sensor

What the Quest DEH 3000R Controls

The DEH 3000R is a low voltage digital humidistat for Quest dehumidifiers, with a remote humidity and temperature sensor that mounts apart from the control. It runs on 24 VAC from the dehumidifier and never touches line voltage, and its part number is 4028531. The control range is 35 to 70 percent relative humidity, read to plus or minus 5 percent, across an operating range of 10 to 95 percent. Temperature is sensed from 30 to 90 °F. The dehumidifier output holds a band of about 3 percent around the setpoint. A room set to 50 runs down to 47 and rests until it drifts back to 53. A fan mode runs the unit's blower continuously or only on demand. A ventilation output drives a damper, held open, held closed, or on a programmed schedule with separate weekday and weekend blocks. Each block carries a morning and a night routine with open and closed durations set in 5 minute steps up to an hour. A high temperature cutout, set at 99 °F from the factory and adjustable, shuts everything down if the room overheats. Features include a dry cycle timer and an auto reboot after power loss. A tripped breaker overnight does not leave the room unguarded until morning. The backlit LCD shows time, day, humidity and temperature at rest, and adds setpoint, fan, mode and damper state when running. The back panel carries terminals for 24 VAC, damper, dehumidifier, fan, on and off detect, and a 5 A auxiliary relay. The control measures 4.95 by 1.06 by 4.19 in. Compatible units run from the Quest 70 through the Dual 105, 155, 165, 205 and 225, the 335, the 506, the 746 and the 876. It is not for the 110 and 150 overhead units.

Placing a Remote Dehumidifier Humidistat Where the Reading Counts

A remote dehumidifier humidistat is only as good as the air its sensor sits in, and that is the whole reason for the separate sensor. Mount the sensor about 5 ft off the floor, in the canopy's air, away from the dehumidifier outlet, the supply duct and any direct lamp heat. A sensor in the dehumidifier's own dry air stream shuts the unit off early and lets the far end of the room climb. Run the sensor on 24 gauge four conductor solid wire, the kind sold as two line telephone cable, and keep the run under 100 ft. Heavier wire will not seat in the splice connectors Quest supplies. Wire the control to the dehumidifier's low voltage terminals and nothing else. The controller is a 24 VAC device, and line voltage on its terminals ends it. Set the humidity target for the stage, then leave the 3 percent band to do its work rather than chasing the display. Set the high temperature cutout a few degrees above the hottest the room is allowed to get. A failed cooling stage then trips the dehumidifier off instead of adding its heat to the problem. Use the ventilation schedule to bring outside air in during the cool part of the day where the room allows it. Put the control itself at eye height by the door, where the LCD gets read on the way in and out. Check the sensor reading against a handheld meter at the start of each cycle. A reading that has drifted outside the 5 percent band means a sensor that wants cleaning or replacing before the next cycle.

Key Features

• Remote humidity and temperature sensor: Mounted in the canopy's air, up to 100 ft of wire from the control.
• 35 to 70 percent setpoint: Read to plus or minus 5 percent, with a 3 percent band around the target.
• 24 VAC, low voltage: Powered from the dehumidifier, never line voltage.
• Ventilation schedule: Damper open and closed routines by weekday and weekend, in 5 minute steps.
• Fan on or auto: Continuous blower or on demand.
• High temperature cutout: Factory 99 °F, adjustable.
• Auto reboot and dry cycle timer: The room is covered again after a power loss.
• Backlit LCD: Time, day, humidity, temperature, setpoint and mode at a glance.
• Quest part 4028531: For the Quest 70 through the 876; not the 110 and 150 overhead units.

Technical Specifications