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SunStat Relay III for extending your system beyond 15 amps

SKU# 500880

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Shipping Information

This is an add-on item, that is eligible for FREE shipping as a part of an order over $149.


The Relay III must be installed with and can only be controlled by either a SunStat Connect 500875, a SunStat Command 500850 or a SunStat Core 500825  thermostat.

Features and Benefits:

  • Built-in Class A GFCI  test light and button with 5-milliamp trip for safety
  • Dual-voltage 120/240 VAC
  • LED indicator lights  for power, heating, GFCI test/trip modes and troubleshooting
  • Paintable cover  for a custom installation
  • Controls up to  150 sq. ft. (1800 watts) at 120 V, or 300 sq. ft. (3600 watts) at 240 V
  • 3-year manufacturer warranty


UPC 840213158156
What's In The Box Relay, wire nuts, screwdriver, mounting screws
Individual Items 1 SunStat Relay III, 1 Sensor Wire
Voltage 120 VAC /240 VAC
Inside Box Width 1 11/16" (42.9 mm)
Inside Box Height 2 3/4" (69.8 mm)
Inside Box Depth 15/16" (23.8 mm)
Display Height 1 3/4" in. inches
Display Width 2 1/4" in. inches
Manufacturer Watts Radiant
Instructions + Video

Instructions + Video

Instruction Manual
Electrical Box Recommended Size Deep Box
Floor Sensor Included Yes
Floor Sensor Length Ft 15' Sensor
Floor Sensor Length Meters 4.57
Floor Sensor Type Thermistor, 10k NTC type, double insulated
Floor Sensor Resistance Range (@ 20,000) 8-14k
Floor Temperature Sensing Primary Floor temperature
Ambient Air Temperature sensing Mode Yes
Ambient Air w/ Floor Temp option Yes
Location / Use : Indoor Only Indoor Dry Location Only
GFEP / GFCI Protection (Ground Fault Circuit Interrupter) 5 mA Class A Built In - With Test Button Feature & indicator light
More Details

More Details

Warranty from Manufacturer 3 yr
Control Multiple areas Yes
Smart Technology/Early Start Yes
Manual Temperature Override Possible Yes
Regulator Mode option No
Safety Listing Safety Listed in USA & Canada : UL 873, UL 943 & CSA C22.2 No. 24, CSA/CAN C22.2 No.144, ETL Control No. 3037530
Programming Method None
7 Day Prog (Su - Sa) No
No Battery Required No Battery Required
Minimum Display Temp 32° F (0° C)
Maximum Display Temp 99° F (37° C)
Accuracy Degrees F +/- 0.9° F (0.5° C)
Minimum Setting Temp 40° F (4° C)
Maximum Setting Temp 99° F (37° C)
Repairable Heating Wire No serviceable parts
Packaging Easy Open Cardboard - No frustration

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