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Low Voltage Thermostat, Stages Cool 2, Stages Heat 4

Price $456.50 / each

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  • Item # 1RZY2
  • Mfr. Model # YTH9421C1002
  • UNSPSC # 41112209
  • Catalog Page # N/A
  • Shipping Weight 1.5 lbs.
Country of Origin MexicoCountry of Origin is subject to change.
Note: Product availability is real-time updated and adjusted continuously. The product will be reserved for you when you complete your order. More

Technical Specs

  • ItemLow Voltage Thermostat
  • Stages Heat4
  • Stages Cool2
  • Temp. Settings per Day4
  • Programs per Week7
  • Terminal DesignationsR, RC, RH, C, W1, W2, W3, Y, Y2, G, L, 1, 2, 3, Out1, Out2, In1, In2, Dats1, Dats2, Hum1, Hum2, Dhm1, Dhm2, Vnt1, Vnt2
  • System SwitchingAuto-Heat-Cool-Off-Emergency
  • Fan SwitchingAuto-On-Circulate
  • Display TypeLCD, Backlit
  • Key Pad LockoutYes
  • Programmable FanYes
  • Humidification ControlYes
  • Remote Sensing CapabilityYes
  • Battery BackupNo
  • Low Battery IndicatorNo
  • Dual Transformer CompatibleYes
  • Power MethodHardwired
  • Voltage24VAC
  • Height4-9/16"
  • Width6"
  • Depth1-3/8"
  • ColorWhite
  • Control RangeHeat 40 Degrees to 90 Degrees F, Cool 50 Degrees to 99 Degrees F
  • FeaturesTouch Screen selectable 7 Day or Nonprogrammable, 3 Heat/2 Cool Conventional or 4 Heat/2 Cool Heat Pump System, Humidification, Dehumidification and Ventilation Control with 3 Wires to Thermostat
  • For Use WithModule or EnviraZONE panel
  • IncludesThermostat and Interface Module
  • Green Environmental AttributeProduct Contributes to Reducing Energy Consumption
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Compliance and Restrictions

  • Green Product - This item has been designated by the manufacturer as an environmentally preferable product (EPP) because this item has one or more environmentally preferable attributes. For additional information, see the Tech Specs tab on the product description page.


Features menu-driven programming and is suitable for residential or light commercial applications, including gas, oil, electric, or millivolt systems.

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Product Q&A

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what is the interface for? thnks
2 years, 3 months ago
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As the description indicates, the Honeywell YTH9421C1002 is a touch screen thermostat with an equipment interface module (EIM).

The EIM is where the actual control wires for the system get attached. From the EIM to the thermostat there are 3 wires, two are for power with the third being for communication between the thermostat and the EIM.

The YTH9421C1002 is an ideal device when upgrading to a multistage system that would require more wires going to the thermostat than currently exist or you are in a situation where you cannot pull additional wires to the thermostat.
2 years, 3 months ago
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