The Robertshaw 8406 is a single-stage thermostat designed to control 24 VAC cooling systems.
WARNING
If this thermostat REPLACES a thermostat that contains mercury, DO NOT discard the old thermostat in the regular trash. Mercury is harmful to humans and the environment. For this reason, do not open, break, or crush the mercury cell. If mercury leaks from a damaged cell, DO NOT touch or handle mercury with bare hands. Use protective, non-absorbent gloves to place mercury into a sealable container. Fill the container with sand or another absorbent material and seal the container completely. 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. El Paso, TX 79906 Attn: Mercury Recycling Center
Step 1: Replacing Existing Thermostat
Wiring Table
Old Terminal | New Label | Description |
M,W,Rh,R5 or 5 | Rh | Heat transformer, hot side |
V or Rc | Rc | Cool transformer, hot side |
Y or Y6 | Y1 | Cooling control |
F or G | G | Fan control relay |
Step 2: Installing Model 8406 Thermostat
NOTE: FOR NEW INSTALLATIONS, MOUNT THERMOSTAT ON INSIDE WALL, FIVE FEET ABOVE THE FLOOR. DO NOT INSTALL BEHIND A DOOR, IN A CORNER, NEAR AIR VENTS, IN DIRECT SUNLIGHT, OR NEAR ANY HEAT OR STEAM GENERATING FIXTURES. INSTALLATION AT THESE LOCATIONS WILL AFFECT THERMOSTAT OPERATION.
COOL ONLY 2-WIRE
SINGLE TRANSFORMER
TERMINAL LEGEND – 8406 | |||
TERM | EQUIPMENT TO CONNECT | REQ? | TERMINAL FUNCTION |
Rh | 24VAC hot connection | Yes | For input of 24VAC hot side of heat transformer |
Rc | 24VAC hot connection | Yes | For input of 24VAC hot side of cool transformer |
Y1 | Compressor Connection | Yes* | Energizes on a call for cooling |
G | Indoor fan connection | Yes | Energizes with Y1 & W1 terminals or with FAN option switched to the ON position |
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). THIS CAN DAMAGE THE AIR CONDITIONING SYSTEM AND CAUSE PERSONAL INJURY.
Settings System
Temperature Differential
The temperature differential is factory set at 1.0°F (.5°C). This means that whenever the room temperature changes by one degree Fahrenheit from the temperature setting, the system will turn on. If the system turns on too often, increase the temperature differential
Changing Fahrenheit (°F) to Celsius (°C), the Temperature Differential, and the Filter Monitor
Once the filter timer has expired, the CHECK FILTER will turn on and stay on. To clear the message and reset the timer:
Backlit Display
This thermostat is equipped with a backlight to make nighttime temperature adjustments quick and easy. Press the button to activate the backlight. The backlight will turn off after about 10 seconds of inactivity.
Reset
To reset the thermostat press the RESET button located above the upper left corner of the display.
Step 5: Troubleshooting
Symptom | Remedy |
Thermostat does not turn on system. | Check wiring (see Installation section). |
Thermostat turns system on and off too frequently. | Increase temperature differential (see Changing the Temperature Differential section). |
Display is blank, flashing or constant LO BATT. | Replace batteries. |
Thermostat does not display proper room temperature. | Check F/C (Fahrenheit/Celsius) setting. See Changing Fahrenheit (F) to Celsius (C). |
Note: Although the thermostat has a low battery indicator, replace the batteries once a year to prevent leakage and to prevent the thermostat and heat/cooling system from shutting down due to a lack of battery power in the thermostat.
If problems with the thermostat cannot be resolved, call: Technical Support: at (800) 445-8299
Monday-Friday 7:30 AM – 5:30 PM CST
For after-hours service, a 24-hour automated helpline is available.
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 the date of purchase. This warranty and our liability do not apply to batteries or merchandise that has been damaged by misuse, neglect, mishandling, alterations, improper installation, or use in a way other than in accordance with Invensys Controls America’s recommendations and instructions.
Invensys Controls Americas agrees to repair or replace at its option any thermostat under warranty provided it is returned within the warranty period, postage prepaid, with proof of the date of purchase. The cost of thermostat removal or reinstallation is not the responsibility of Invensys Controls Americas.
Repair or replacement as provided under this warranty is the exclusive remedy of the consumer. Invensys Controls Americas shall not be liable for any incidental or consequential damages for breach of any express or implied warranty on this product, or under any other theory of liability. Except to the extent prohibited by applicable law, any implied warranty of merchantability or fitness for a particular purpose on this product is limited to the duration of this warranty.
Some states do not allow the exclusion or limitation of incidental or consequential damages or allow limitations on how long an implied warranty lasts, so the above limitations or exclusions may not apply to you. This warranty gives you specific legal rights, and you may also have other rights which vary from state to state. For warranty returns, send thermostat, shipping prepaid to:
Invensys Controls Americas
Warranty Claims Department 515 S.
Promenade Corona, CA 92879-1736
Controls Americas
191 E. North Avenue
Carol Stream, Illinois 60188
United States of America
Download Manual:
Robertshaw 8406 NON-PROGRAMMABLE Thermostat User Manual
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