Watts 500670 Owner's Manual

5

sensor

2.  Installation

Remove the Thermostat Face

1. Remove the thermostat Front Module 

from the Power Module by opening the door 

and loosening the screw.

2.  2. Pull outward near the bottom on the 

Front Module and lift off. Be careful not 

to bend or damage the 14-pin electrical 

connector on the back of the Front Module.

Prepare the Wiring

1. Find a location for your thermostat. It is suitable for indoor use only, on 

insulated or uninsulated walls.  Locate it about 4

1

⁄

2

 feet to 5 feet above the 

floor on an inside wall.  Make sure it is well ventilated and not located in a 

confined space such as a small closet or cabinet. Avoid placing it near other 

heat sources such as hot-water piping, heat duct, wall-mount lighting, and 

direct sunlight to help prevent adversely affecting the thermostat.

2.  Turn off the power to the floor warming system at the main circuit panel 

before doing any electrical work.

3.  A qualified electrician should run a dedicated circuit from the main circuit 

panel to the thermostat location.

4.  If a dedicated circuit is not possible, you may tap from another circuit in the 

room.  Make sure there is enough load capacity (amps) to handle the addition 

of your floor warming system, and that it is NOT wired in series with any other 

Owner’s Manual

Your new SunStat Pro thermostat is designed to control the voltage to 

either a 120VAC or 240VAC resistive floor warming system.

Please follow this manual for complete installation and operation instructions.  

If you have any questions or comments, try calling Technical Support at  

1-888-432-8932.

  CAUTION

:  Make sure you are qualified and are familiar with house wiring.  

This is a line voltage device that could cause serious injury or damage if 

improperly installed.

Connect Wires

1. Match and connect the two wires 

marked “LINE1” and “LINE2” to the 

power supply wires using the wire nuts 

provided.

2.  Gently tug on the wires to make sure 

they are secure, otherwise a wire could 

loosen and cause failure.

3.  Overwrap the wire nuts with electrical 

tape to better secure them to the wires.

4.  Match and connect the two wires 

marked “LOAD1” and “LOAD2” to the 

floor warming system lead wires and 

secure these wires the same way.

5.  Connect the house ground wire to the 

green or bare lead wire(s) of your floor 

warming system.

6.  Insert the ends of the floor sensor 

wire into the “SENSOR” terminals (1 and 

2) and tighten the screws.  There is no 

polarity, so it does not matter which wire 

end goes into which terminal.

  CAUTION: 

 Before continuing, make 

sure your power supply voltage matches 

the voltage rating of your floor warming 

system.  

Connecting 240V to a 120V floor warm-

ing system will cause overheating and 

damage to the system and may damage 

the control, other wiring, floor coverings, 

etc.

Remote Control

1. If you want to connect your thermostat to a remote control device, such as 

a home automation system, first make sure that the remote device has a “dry 

contact, normally open” output (an un-energized switch, such as the contacts on 

a relay).  Many home automation systems come with such an output that opens 

or closes at specified times.

2.  Pull 2-conductor wire, size 18- to 24-guage, through the wall from the remote 

device, into this electrical box.

3.  Connect the wire ends into the “SETBACK” terminals (5 and 6) and tighten 

the screws (no polarity).

SunStat Relays

1. If you want to use your thermostat to drive a SunStat Relay(s) (ask your dealer 

about this convenient way to control larger systems with one thermostat), first 

read and follow the instructions for the SunStat Relay thoroughly.

2.  Pull 2-conductor wire, size 18- to 24-gauge, through the wall from the SunStat 

Relay, into this electrical box.  This wire may be up to 100 feet (30 m) in length 

from the thermostat to the last SunStat Relay installed.

3.  Connect the wire ends into the “RELOUT” terminals (3 and 4) and tighten the 

screws(Observe polarity of the wires when connecting to the SunStat Relay).

Mount the Thermostat

1. Carefully fold and press the wires back into the electrical box.  Do not use 

the thermostat to push them in, as this may cause connections to loosen and 

possible failure.

2.  Secure the thermostat Power Module into the box with the mounting screws 

provided.

3.  Carefully align the Front Module with the 

Power Module to avoid bending any of the 

pins on the Front Module while snapping 

them together. 

4.  Tighten the screw.

5.  Switch on the power at the main circuit 

panel.

NOTE to contractors: After installing the 

thermostat, be sure to:

  a.  Do a Quick Setup (section 3),

  b.  

Temporarily override the setpoint 

SunStat Pro

Programmable Thermostat

Model 500670

1-4

from 

power 

supply

to

floor 

warming 

system

1.  Preparation

1. Unpack your thermostat and make sure everything is in good condition:

•

Thermostat

•

Floor sensor

•

Small screwdriver

•

Mounting screws

•

Wire nuts for wiring connections

If any parts are missing or damaged, contact the store where you purchased 

this thermostat.  Do not install a damaged part.

2.  Gather the following tools and supplies:

  •Phillips screwdriver, hole saw

  •Wire strippers, “fish tape”, other electrical tools

  •Electrical box for thermostat:

a. If you are connecting to power leads from only 1 or 2 floor warming 

systems, you may use a single-gang, 3

1

⁄

2

 inch deep box.

b. If you are connecting to power leads from 3 floor warming systems, 

use a 4x4x2

1

⁄

8 

inch or deeper box (not a 2-gang box) when your wall studs 

are still exposed. Install a single-gang “mud-ring” cover on the box before 

installing drywall materials.

c. For more than 3 floor warming systems or other layouts, you may need 

to install a junction box to connect the power leads together. Then use 

house wire to connect between the junction box and the thermostat 

electrical box. See the installation instructions for your floor warming 

system for more information.

  ALWAYS:  Wire all circuits as Class 1, Electric Light and Power Circuits.

  ALWAYS:  Wire all circuits with insulation rated 600V minimum.

  ALWAYS:  Mount this control only to a grounded metallic box or a 

  nonmetallic box.

  ALWAYS:  Use power supply wires suitable for at least 90°C.

  CAUTION:  High voltage – disconnect power supply before servicing.

  CAUTION:   The GFCI in this control does not protect against shock if both 

bare conductors are touched at the same time.

device, including other GFCIs.

5.  The circuit breaker in the main circuit panel should be 15 amps maximum 

for a floor warming system totaling 12 amps or less.  For larger systems up 

to 15 amps, use a 20 amp maximum circuit breaker. Never exceed 15 amps 

on this thermostat.  You may consider using an arc-fault (AFCI) type circuit 

breaker for additional protection.

6.  Mount the electrical box. 

7.  Pull the power supply wiring into this box, leaving about 6 inches of wire.

8.  Pull the floor sensor wire and the power lead wires from your floor warming 

system up the wall, into this box.  Refer to your floor warming system 

installation instructions for placement of the floor sensor tip into the floor area.

Note:  The sensor wires should not be run in the same conduit as line voltage 

wires to avoid possible interference.  If the sensor lead wires are not long 

enough, they may be extended an additional 15 feet (4.5 m) using minimum 

20-gauge 2-conductor wire or up to 50 feet (15 m) using shielded wire.

power 

module

front 

module