Robertshaw 8425 User Manual
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Robertshaw 8425 User Manual

Digital non-programmable thermostat quick start installation
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NeW
110-1090B
Application
The Robertshaw 8425 is a multi-stage thermostat designed to control
24 VAC heat pump systems.
Features
• Large backlit display
• Adjustable 1
1.5°C)
• Adjustable 2
3.0°C)
• Adjustable 2
• Compressor short cycle protection
• Accuracy within ±1°
• Zone system compatible as a master thermostat
• Permanent memory retention
• Fahrenheit/Celsius display option
• Adjustable from 45°F to 90°F (7°C - 32°C)
• Quick wire terminal block
®
st
stage temperature differential: 1.0°F to 3.0°F (0.5°C to
nd
stage temperature differential: 1.0°F to 6.0°F (0.5°C to
nd
stage delay (10-40 minutes)
8 425
G
GAS
ELECTRIC
2 Heat / 2 Cool
User's Manual

Quick Start

Installation
1
DIGITAL
NON-PROGRAMMABLE
THERMOSTAT
O
E
OIL
HEAT PUMP
H

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Summary of Contents for Robertshaw 8425

  • Page 1: Quick Start

    2 Heat / 2 Cool User's Manual Quick Start Installation 110-1090B Application The Robertshaw 8425 is a multi-stage thermostat designed to control 24 VAC heat pump systems. Features • Large backlit display • Adjustable 1 stage temperature differential: 1.0°F to 3.0°F (0.5°C to 1.5°C)
  • Page 2 Return the mercury or mercury products, in a sealed container, to Invensys Controls Americas or a local recycling center for proper disposal. If you have any questions, call Robertshaw technical support at 1-800-445-8299. Invensys Controls Americas 28C Leigh Fisher Blvd.
  • Page 3 4. Remove existing thermostat base from wall. Figure 1 Step 2: Installing Model 8425 Thermostat NOTE: FOR NEW INSTALLATIONS, MOUNT THERMOSTAT ON INSIDE WALL, FIVE FEET ABOVE THE FLOOR. DO NOT...
  • Page 4 4. Remove the cover using a coin or screwdriver (Figure 3). Set aside. a u to o o l o ff c h e a t ° M O N s e t v a c c lo c k te m p h o ld r u n /s...

  • Page 5: Wiring Diagrams

    Wiring Diagrams ♦ HEAT ONLY HEAT/COOL 3-WIRE 4-WIRE SINGLE TRANSFORMER SINGLE TRANSFORMER Transformer Transformer 24 VAC 120 VAC 24 VAC 120 VAC Heating Heating Control Control Cooling Control Control Control W2/E W2/E HEAT ONLY COOL ONLY 2-WIRE 3-WIRE SINGLE TRANSFORMER SINGLE TRANSFORMER Transformer Transformer...

  • Page 6: Reversing Valve

    HEAT PUMP WITH HEAT PUMP WITH COOL ACTIVE HEAT ACTIVE REVERSING VALVE REVERSING VALVE Transformer Transformer 24 VAC 120 VAC 24 VAC 120 VAC Compressor Compressor Contactor Contactor Relay Relay Reversing Valve Reversing Valve W2/E W2/E NOTE: Make sure the HP swtich is in the HP NOTE: Make sure the HP swtich is in the HP position.
  • Page 7 TERMINAL LEGEND - 8425 TERM EQUIPMENT TO CONNECT REQ? TERMINAL FUNCTION 24 VAC hot connection For input of 24VAC hot side of transformer 24 VAC common connection For input of 24VAC common side of transformer System fault indicator For connection of system...

  • Page 8: Step 3: Testing The Thermostat

    Step 3: Testing the Thermostat WARNING: DO NOT SHORT (JUMPER) ACROSS TERMINALS OF GAS VALVE OR SYSTEM CONTROL TO TEST OPERATION. THIS WILL DAMAGE THE THERMOSTAT AND VOID YOUR WARRANTY. CAUTION: DO NOT SWITCH SYSTEM TO COOL OR LEAVE IN COOL MODE IF THE TEMPERATURE IS BELOW 50°F (10°C).

  • Page 9: Temperature Differential

    Step 4: Customizing the Thermostat Settings ♦ System Cool: The thermostat controls the cooling. Off: The heating and cooling systems are off. Heat: The thermostat controls the heat. Emer:The thermostat controls the second stage emergency heat. Use only when the primary stage of heat is not functioning or requires service.

  • Page 10: Backlit Display

    8. Wait five seconds or press and the display will switch to the fil- ter monitor setting. 9. CHECK FILTER and the length of hours for the filter monitor will be displayed. 10. Use the to adjust the filter timer from 0 (OFF) to 9900 hours.

  • Page 11: Step 5: Troubleshooting

    Step 5: Troubleshooting Symptom Remedy Check wiring (see Installation Thermostat does not turn on system. section). Thermostat turns system on and Increase temperature differential (see Changing the Temperature off too frequently. Differential section). Move Electric/Gas switch to System fan does not operate either gas or electric, to match properly.

  • Page 12: Two-Year Limited Warranty

    Invensys Controls Americas warrants to the original contractor installer, or to the original consumer user, each new Robertshaw thermostat to be free from defects in materials and workmanship under normal use and service for a period of two (2) years from date of purchase.

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