Transmitter-Room

Supported Applications

The ACI Room Series is a family of wall-mounted, single-point room temperature transmitters that report space temperature to a building automation system (BAS) or controller. Each transmitter provides a 4-20 mA (2-Wire loop powered) output with an optional voltage output of 1-5 VDC or 2-10 VDC, making it suitable for zone temperature sensing in commercial HVAC control.

Beyond straight temperature sensing, the family supports optional occupant-interface functions: a setpoint output (with or without offset resistance), an override input that provides a normally open "Dry Contact" closure, and a local LCD display. The enclosure is offered in two versions, "R" and "R2", both molded in Beige ABS Plastic (UL94-HB). ACI warns that wiring must never share a conduit with line voltage (24/120/230 VAC).

Operating Conditions & Performance

The sensing element is a platinum RTD with a positive temperature coefficient (PTC) and a single sensing point conforming to DIN EN 60751 (IEC 751), offered as a 100 Ω nominal (A/TT100, A/TTM100) or 1 KΩ nominal (A/TT1K, A/TTM1K) element with a tolerance of ±0.06% Class A.

Transmitters are powered from an unregulated or regulated +8.5 to 32 VDC supply (reverse-polarity protected) drawing 25 mA minimum. Maximum load resistance tracks the supply: a 250 Ω load needs +13.5 to 32 VDC and a 500 Ω load needs +18.5 to 32 VDC. Wiring lands on non-polarity-sensitive screw terminal blocks sized for 16 AWG to 26 AWG conductors.

The unit operates over 1.5 to 50 °C (35 to 122 °F), stores at -40 to 65 °C (-40 to 149 °F), and tolerates 10 to 95% RH non-condensing humidity. The enclosure measures 2.75" (69.85 mm) wide by 4.50" (114.30 mm) high by 1.12" (28.55 mm) deep. Calibrated accuracy is +/- 0.2% for temperature spans under 500°F (260°C), with temperature drift of +/- 0.04%/°F for spans under 100°F (38°C) and +/- 0.02% for spans over 100°F (38°C).

Configuration Options

The lineup differs first by sensing element: the A/TT100 and matched A/TTM100 use the 100 Ω platinum element, while the A/TT1K and matched A/TTM1K use the 1 KΩ element. Matched TTM parts can be ordered with a NIST certificate, for example the 5-point option denoted by the -5PTNIST suffix.

Enclosure style is the "R" version or the "R2" version, both sharing the same footprint but differing in enclosure design. Feature options layer on top of the base transmitter: an "S" setpoint output adds a second 4-20 mA signal (Direct Acting default with 4 mA at far left and 20 mA at far right, or optional Reverse Acting), an "O" override adds a normally open dry-contact input, and an "LCD" option adds a 3 ½ digit display reading -199.9 to 199.9.

The override dry contact is rated from a minimum of 10 uA at 1 VDC up to a maximum of 50 mA at 24 VDC. Output type can be current 4-20 mA (2-Wire loop powered) or voltage 1-5 VDC or 2-10 VDC, and setpoint variants can be supplied with or without an offset resistance.

Key Product Differences

Room Series part numbers begin with the sensor series and element (A/TT100, A/TT1K, A/TTM100, A/TTM1K) followed by the enclosure and feature codes and the output signal.

• Element: TT100 / TTM100 (100 Ω) and TT1K / TTM1K (1 KΩ), with matched TTM parts available NIST certified.
• Enclosure version: "R" and "R2".
• Feature options: setpoint output (S), override dry contact (O), and local LCD display (LCD), which may be combined as RS, RO, RSO, R2S, R2O and R2SO.
• Output signal: 4-20 mA current or 1-5 VDC / 2-10 VDC voltage.

Representative catalog part numbers include A/TT100-R-2-LCD, A/TT1K-RS-4-LCD, A/TT1K-RSO-4-C5 and the NIST-certified A/TTM1K-R2-4-5PTNIST. Companion accessories include the A/ROOM-FOAM-PAD thermally insulated backing for solid walls.