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Alarm.com Smart Thermostat Wiring & Configuration (ADC-T3000 / ADC-T2000)
This guide helps you swap an existing thermostat with an Alarm.com Smart Thermostat (ADC-T3000 or ADC-T2000), verify wiring, and configure system settings for proper operation.
Before You Start
- Confirm the HVAC system is already wired to a compatible low-voltage thermostat (24 VAC).
- Turn power OFF at the breaker before removing the old thermostat.
- Take clear photos of the existing wiring and note any jumpers or labels.
- Check the old manual: some thermostats show two label sets (Conventional vs Heat Pump).
Tip: Wire colors are not standardized, but common patterns can provide clues (e.g., orange often used for O/B on heat pumps; white for W/AUX).
Identify the Previous Wiring
- Match old terminal names to the Smart Thermostat terminals. If a terminal doesn’t map cleanly, see Non-Standard Wires.
- Look for jumpers on the old stat (e.g., E jumpered to W on some heat-pump setups).
Standard Wire Mapping
ADC-T3000 Terminals
| Terminal | Function |
|---|---|
| RC | 24V power (right side bus: C, Y, Y2, G, O/B) |
| RH | 24V power (left side bus: W, W2, Z) |
| W | Heat stage 1 (Conventional) / Aux stage 1 (Heat Pump) |
| W2 | Heat stage 2 (Conventional) / Aux stage 2 (Heat Pump) |
| C | Common (thermostat power) |
| Y | Cool stage 1 (Conventional) / HP stage 1 (Heat Pump) |
| Y2 | Cool stage 2 (Conventional) / HP stage 2 (Heat Pump) |
| G | Fan |
| O | Reversing valve – O |
| B | Reversing valve – B |
| Z1 / Z2 | Configurable (W3, Humidifier, Dehumidifier, Ventilation) |
ADC-T2000 Terminals
| Terminal | Function |
|---|---|
| RC | 24V power (right side bus: C, Y, Y2, G, O/B) |
| RH | 24V power (left side bus: W, W2, Z) |
| W / W2 | Heat stages (Conventional) / Aux stages (Heat Pump) |
| C | Common (thermostat power) |
| Y / Y2 | Cool stages (Conv.) / HP stages (HP) |
| G | Fan |
| O/B | Reversing valve (O/B). Also used in O/B zoning & master/slave (uncommon). |
| Z | Configurable (W3 / O/B Zoning per FW) |
Non-Standard Wires (Legacy Stats)
| Legacy Terminal | Meaning / Action |
|---|---|
| L | Outdoor reset or service light → Tape off |
| S1 / S2 | Sensors → Tape off |
| dh | Dehumidifier → see Smart Humidity Control quick start |
| T | Outdoor reset/thermistor (GE/Trane/AS, some Carrier) → Tape off |
| E / W/E | Emergency Heat. Often map to W; if AUX already used, tape off. Alarm.com EMER mode handles HP behavior. |
| U1 | Honeywell configurable → check old manual |
| K | Combined Y+G on some Honeywell → separate to Y and G on Smart Thermostat if possible |
| GND / ODT | 2-wire outdoor sensor → Tape off |
| Data / A-D / 1-4 | Proprietary → Not compatible without HVAC rewiring |
R, RH & RC Handling
ADC-T3000
If only one R wire is present, land it on either RC or RH and select that terminal during setup—the thermostat digitally jumpers to the other R. If both RC and RH wires exist, no physical jumper is needed; select both during configuration.
ADC-T2000
If only one R wire is present, connect to RH. If both RH and RC exist, remove the black jumper on the backplate and land both wires.
Uncommon Wiring Scenarios (FAQs)
- W/W1 & Y jumpered (old HP stats): Map wires normally; Smart Thermostat uses Y for heat pump compressor and W/W2 for Aux.
- W2 present but no W1: Move that wire to W.
- Both O and B wires: Check the old manual. If unsure, start with O. On some Trane stats, B may be Common, not a reversing valve.
- W2 and Y2 jumpered on HP: Remove the legacy jumper; map wires normally.
- Two-wire heat-only system: Yes—use R and W (configure as Normal HVAC, Fossil heat type).
- Totaline BOW terminals: BOW may act as O/B (HP) or W (conventional). Confirm system type first.
- Standalone transformer power: Possible only for heat-only or cool-only systems (transformer into R and C; remove jumper as applicable).
- Dual fuel / hybrid: Supported; separate circuits via RC and RH. See your pro resources.
Heat Type & HVAC Configuration
- Electric: Thermostat controls the fan (forced-air electric, most HP Aux stages).
- Fossil: Furnace controls the fan (gas/oil hydronic, baseboard, dual-fuel, furnaces with built-in fan delay).
- Radiant floor: Use Fossil heat type (pro install recommended).
Non-Standard Systems
- Dual Fuel: Heat Pump HVAC type + Fossil heat type.
- Heat-Only / Cool-Only: Normal HVAC type (even if only one mode is present).
- O/B Zoning (ADC-T3000): Normal HVAC type. Land O and B; auto-detected during wiring.
- O/B Zoning (ADC-T2000): Set Z = O/B Zoning to expose O/B in Installer tab (O = cooling allowed, Z = B = heating allowed).
Choosing a Local Configuration
Set mode to OFF before changing installer settings. Local config allows operation even without cloud connectivity.
ADC-T3000
Automatically detects wires during install. See the installation guide for on-screen prompts.
ADC-T2000 — FW 1.30+
- Mode = OFF (only temperature shows).
- Press and hold the mode button 5s → version.
- Press and hold again 5s → HVAC setup.
- Use ▲/▼ to select configuration; press mode to confirm.
Recommended: After local selection, run Get Current Values from Partner Portal/MobileTech so the cloud reflects local settings.
ADC-T2000 — FW < 1.30
- C2H2 = Normal systems (defaults heat type to Electric).
- P2A2 = Heat Pump systems (defaults O/B to O; set to B via backend if needed).
Note: O/B zoning on T2000 must be configured via Partner Portal/MobileTech.
Z / Z1 / Z2 Terminals
ADC-T3000
Configure Z1/Z2 via Settings → Installer → Continue → Z1/Z2 as: W3 (3rd heat/aux), H (humidifier), DH (dehumidifier), or V (ventilation: HRV/ERV/air baffle).
ADC-T2000
- FW 1.30+: Z can be W3 or O/B Zoning (Master uses O/B; Accessory wired normally).
- FW < 1.30: Z only supports W3 (3rd stage heat / 3rd stage Aux on HP).
Built-In System Delays (Protection)
- Compressor Delay: 5 min default (all AC/HP) — prevents short cycling.
- Staging Delay: 10 min default — time before adding next stage (can be overridden by differential).
- Fan Purge: 1 min default — clears conditioned air after setpoint reached.
- Heating/Cooling Differential: 3°F default — temp delta to trigger next stage earlier.
- Fan Circulation: Defaults: Period 10 min; Duty 25% — air quality without continuous fan.
Next Steps & Resources
- Need additional documentation? Visit User Guide Documents.
- Explore Home Automation or Security Systems.
- Prefer a pro? Contact True Protection.
