Watts SunStat Pro II 500775BB, SunStat Pro II 500775WB, SunStat Pro II 500775HB, SunStat Pro II 500775SB, SunStat Pro II 500775 Nstallation & Operation Manual

Installation &
Operation Manual

SunStat® Pro II
Programmable Thermostat
Model 500775 (-BB, -HB, -SB, -WB)

Local building or electrical codes may require modifications to the information
provided. You are required to consult the local building and electrical codes
prior to installation. If this information is not consistent with local building or
electrical codes, the local codes should be followed.

Items included

Unpack the thermostat control and make sure every thing is in good condition.
Do not use a damaged control or part. The package comes with these items:

(1) Thermostat
(1) Thermostat Floor Sensor
(5) Wire Nuts (Marettes®)
(2) Mounting Screws
(1) Screwdriver

Tools and supplies needed

• No. 2 Phillips screwdriver

• Hole saw (if installing in an existing wall)

• Wire strippers, wire cutters, and other electrical tools

• Electrical wall box (plastic or metal)*

*A single-gang extra-deep box allows sufficient space to connect 1 or 2
heating mats or cables. For 3 heating mats or cables, a 4-inch square extra­deep electrical box with a single-gang “mud ring” is necessary. Alternately,
a junction box may be installed to connect multiple heating mats or cables,
then run power supply wire from the junction box to the control electrical
box. See the Installation Instructions provided with the floor heating system
for more details.

The SunStat Pro II model 500775 is designed to operate either a 120 VAC or
240 VAC resistance floor heating system. It comes with an easy setup wizard, a
typical Program Schedule ready to go, and a GFCI inside to meet safety needs.

Read this Manual BEFORE using this equipment.
Failure to read and follow all safety and use

information can result in death, serious personal
injury, property damage, or damage to the
equipment.

Keep this Manual for future reference.

Installation must be performed by qualified personnel, in accordance with
local codes and standards. A licensed electrician is recommended.

As with any electrical product, care should be taken to guard
against the potential risk of fire, electric shock, and injury to
persons. The following must be observed:

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

• Wire all circuits with insulation rated 600V minimum.

• Mount this control only to a grounded metallic box or a nonmetallic box.

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

• High voltage – disconnect power supply before servicing.
The GFCI (ground-fault circuit interrupter) in this thermostat control does not

•
protect against shock if both bare conductors are touched at the same time.

•

Do not exceed 15 amps on this thermostat control. Doing so will cause risk
of fire hazard and damage.

• Make sure the house power supply voltage matches the voltage rating of
the floor heating system. Do not apply 240 VAC to a 120 VAC rated system.
Connecting the wrong voltage may cause overheating and damage to the
system, the control, floor coverings, etc.

Installation

Locating the Control

Find a suitable location for the control. Consider the following:

• It is designed for indoor dry location only.

• It may be placed on an insulated or uninsulated wall, preferably an interior
wall to avoid overheating from outside sun heat.

Keep it away from all water sources such as sinks, showers, and bathtubs

•
as well as heat sources such as hot-water piping, heat ducting, wall-mount
lighting, and direct sunlight.

Locate it at a suitable height, normally about 4-1/2’ to 5’ (1.4 m to 1.5 m)

•
from the floor.

Mounting the Electrical Box

•

When mounting on an existing wall, cut the opening for the electrical box for
the control. To make it easier to pull the wiring, wait to install the electrical
box until after all wiring is drawn into this opening.

• When mounting on an open wall, secure the electrical box for the control to
the wall stud. Conduit from the electrical box to the floor is recommended
(check local codes for requirements) for additional protection. Install one
conduit for the floor sensor. Install another conduit for the floor heating
system power leads.

• Refer to the Installation Instructions supplied with the floor heating system
for additional installation details.

Wiring

To prevent the risk of p ersonal injur y and/or death, make sure
power is not applied to the product until it is fully installed and
ready for final testing. All work must be done with power turned
off to the circuit being worked on.

House Wiring

Pull power supply wiring to the control location. Consider the following:

• Leave about 6 to 8 inches (15 to 20 cm) of wire for connections later.
This wiring should be size 12 or 14 AWG following appropriate local code

•
requirements.

A qualified person should run a dedicated circuit from the main circuit

•
breaker panel to the control location. If a dedicated circuit is not possible, it
is acceptable to tap into an existing circuit. However, there must be enough
capacity to handle the load (amps) of the floor heating system being installed
and any possible appliance, such as a hair dryer or vacuum cleaner.

• Avoid circuits that have ballasted lighting, motors, exhaust fans, or hot tub
pumps due to possible interference.

The circuit breaker should be rated 20 amps for total circuit loads up to 15 amps.

•
A 15 amp circuit breaker may be used for total circuit loads up to 12 amps.

A GFCI (ground-fault circuit interrupter) or AFCI (arc-fault circuit interrupter)

•
type circuit breaker may be used if desired, but is not necessary.

Floor Sensor

1. Test the Thermostat Floor Sensor included to make sure it has not been
damaged in handling. Use a digital multimeter set to the 20kΩ range. The
resistance varies according to the temperature sensed. These are approximate
values for reference:

Table 1 – Sensor resistances

Temperature Typical Values

55°F (13°C) 17 kΩ
65°F (18°C) 13 kΩ
75°F (24°C) 10 kΩ
85°F (29°C) 8 kΩ

2. Pull the floor sensor wire up the wall (or conduit) to the control location.
Consider the following:

• Leave about 6 to 8 inches (15 to 20 cm) of wire for connections later.

• The sensor wire may be cut shorter if desired, but do not cut it shorter until
the sensor is fully installed (see below). Re-strip the sensor wire ends 1/8” to
3/16” (3 mm to 4.5 mm) long. If the ends are stripped longer than this they
may short-circuit resulting in an Err2 code.

• If the sensor wire is not long enough to reach the control location, it may be
extended an additional 15 feet (4.5 m) using minimum 20 AWG 2-conductor
unshielded wire, or an additional 50 feet (15 m) using shielded wire. When
using shielded wire, the “shield” must be connected to the lower sensor
terminal, nearest to Bus A. A junction box may be required by local code for
the connection to this extension wire.

3. After the floor heating system is completely installed according to its
instructions, secure the thick sensor tip to the floor. Consider the following:

It must be located halfway between heating wires and at least 1 foot into

•
the heating area.

• Use hot-glue to secure the sensor tip and wire in place.

• Do not cross over a heating wire.

•

Avoid placing it in an area where heating wires are spaced further apart than
the rest of the floor, like a large gap between mats or cables.

•

Avoid placing it in an area where a heat duct or recessed light will cause
improper measurements.

Try to avoid locating it where future items such as a clothes hamper or similar

•
could trap heat and cause improper measurement.

Power Leads from Heating Mat or Cable

Pull the power lead wires from the floor heating system into the control location.
Excess power lead wire may be cut off, but leave about 6 to 8 inches (15 to 20
cm) of wire for connections.

Figure 1

Figure 2

Removing the Thermostat Front Module

1. Remove the Screw Cover at the bottom and loosen the screw.

2. Lift the Front Module away from the Power Module.

Power Module

Load 1

Line 1

Floor Sensor

Connection

Line 2

Load 2

Cover Screw

Front
Module

Screw
Cover

Wiring Connections (see Figure 1 and 2)

Connect the wires as shown in the diagram. Consider the following:

•

Gently tug on the wires to make sure they are secure. For added security,
overwrap the Wire Nut connections with electrical tape.

• If the electrical box is metal, a short length of wire must be secured to the
electrical box from the ground connection.

When connecting the Floor Sensor to the Sensor terminals, it does not matter

•
which wire goes into which terminal.

The Bus A and B terminals are used to communicate with a SunStat Relay

•
II. Please read and follow the instructions provided with the SunStat Relay
II for further details.

Mounting the Thermostat

1. Make sure the power supply to the circuit is turned off at the circuit breaker.

2. Carefully press the wires back into the electrical box.

•

DO NOT use the control to push wires in, as this may cause connections to
loosen and possible failure.

3. Use the Mounting Screws provided to secure to the electrical box and tighten
by hand.

DO NOT over-tighten the screws causing the plastic to distort, as this may

•
cause improper function of the thermostat.

4. Press the Front Module onto the Power Module. Make sure both tabs at the
top are completely engaged.

• DO NOT install the Front Module with power applied on the Power Module,
as this may cause improper function of the thermostat.

5. Secure the screw at the bottom and replace the Screw Cover.

• DO NOT over-tighten the screw causing it to strip. Turn it until snug.