Dramm - Mechanical Thermostat, Single and Two Stage

Brand: Dramm

Mechanical Thermostat, Single and Two Stage

Dramm's mechanical thermostats switch greenhouse heating, cooling and ventilation equipment from a PVC enclosure rated IP54, using a stainless steel coiled sensor instead of a bimetal strip in a painted steel box. The switch contacts are SPDT and carry no load: one set opens on a temperature rise as the other closes, so the thermostat drives a relay or contactor rather than the equipment itself. Control range is 30 to 104 F (0 to 40 C) with a differential of about 1 C, and the dial is recalibrated in place against a reference thermometer rather than being sent back. The housing is rain tight and drip proof but is not rated for immersion, so mount it in the zone air and not where it can be washed down.

The choice is how many switch points you need out of one box. The Single Stage SPDT version has one dial, one stainless coil sensor and one set of SPDT contacts, which is enough to bring a unit heater or a single fan bank on and off at one setpoint. The Two Stage SPDT version has two dials, marked minimum and maximum, with two sensors and two contact sets, so it can stage two heaters, run a two speed fan, or open louvers at the first setpoint and take fans to high at the second. Wiring is otherwise identical on both: the ground goes to the clip provided, the cable enters through the watertight connector, and the contacts switch a control circuit rather than the load. Both cover the same 12 to 240 V range and the same 30 to 104 F control band, so the second stage is the only functional difference between them.

Specifications

Configurations

Key Features

• PVC housing rated IP54 stands up to the wet, corrosive air of a greenhouse
• Stainless steel coiled sensor reads zone air directly, with no painted steel to rust through
• No load SPDT contacts: one set opens on a temperature rise as the other closes
• Control range of 30 to 104 F (0 to 40 C) with a differential of about 1 C
• Dial recalibrates in place: line the mark up with a reference thermometer, then rotate the star hub until it clicks
• Watertight cable connector and a dedicated ground clip are built into the enclosure
• Switching load limits are printed on the thermostat; wire through a relay or contactor and do not exceed them
• CSA approved

Ideal Applications

• Single setpoint on and off control of a unit heater
• Exhaust fan and intake louver control in one greenhouse zone
• Staged heating, bringing a second heater on as the temperature keeps falling
• Two speed fan control with louvers opening at the first setpoint and high speed at the second
• Temperature control in headhouses, packing sheds, warehouses and livestock buildings
• Replacing painted steel thermostats that have corroded or drifted out of calibration

Wire one to a Dramm AME horizontal air flow fan bank or a JetFog cooling system so the fans respond to measured zone temperature instead of a timer.