Step warmfloor DIGI-LUX User manual

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Installation & Operation Manual
Physical Description
The DIGI-LUX Electronic Thermostat / Regulator is a zone control device specially designed for
use with the STEP Warmfloor™ radiant heat system. The DIGI-LUX provides a pulsed output
that complements the self-regulating nature of the STEP Warmfloor™ heating elements to offer
the homeowner the highest energy efficiency while providing better zoned control over personal
comfort.
The DIGI-LUX consists of two pieces (See Figure A):
Thermostat The thermostat is the operator interface for the DIGI-LUX. It
is designed to be flush wall mounted in a place that will be
most representative of the zone it controls. The thermostat
consists of a digital display that indicates the measured air
temperature, a button for changing the control set point and
the air temperature sensor. Air temperature is measured
every 12-15 min. by the thermostat’s microprocessor, which
determines the amount of pulsing (system on/off) needed
for each subsequent interval. This signal controls the
regulator, and switches the regulator on/off as needed.
Regulator The regulator is an intelligent switch that enables/disables
the line voltage in such a way that switching/pulsing does
not harm the transformer(s). It is designed to be surface
mounted adjacent to the transformer(s) that it pulses. The
regulator consists of a printed circuit board mounted inside
of a junction box w/ heat sink. Each regulator is designed to
handle up to 2,500W of load.
The thermostat and regulator are connected together using a 20 foot length of 4 conductor cable that is supplied with each
regulator. For control of a zone with a load larger than 2,500W, up to 4 regulators can be connected to one thermostat for a total
controlled load of 10,000W.
Figure A
Front view of the DIGI-LUX Thermostat and Regulator
DIGI-LUX™ Electronic
Thermostat / Regulator

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Operational Description
The DIGI-LUX is not an on/off control device typical of thermostats used with household heating systems. The DIGI-LUX
is designed to pulse the supply voltage to the STEP Warmfloor™ radiant heat system to help closely match the system
heat output with the heating needs for that zone and to prevent temperature overshoot typical with other heating systems.
This pulsing operation provides you with the maximum level of energy efficiency and highest level of personal comfort
possible.
The pulsing operation of the DIGI-LUX is based upon the users programmed set point and the measured ambient
temperature. If the ambient temperature is below the set point, the DIGI-LUX will pulse the STEP Warmfloor™ system on
to heat up the zone. As the zone temperature begins to approach the programmed set point, the DIGI-LUX will pulse the
system on for shorter time periods. Refer to Figure B for a representation of the pulsing operation of the DIGI-LUX.
Figure B
DIGI-LUX Pulsing Characteristics
The high energy efficiencies achieved with a STEP Warmfloor™ system controlled by a DIGI-LUX is due to the
continuous pulsing operation of the system. This continuous pulsing allows the system to continuously add the right
amount of heat to maintain a constant and comfortable environment. With a traditional forced air on/off controlled heat
system, the system is on and off for long durations requiring significant heat input each time the thermostat calls for heat.
This results in a variable and drafty environment with low energy efficiencies compared to radiant heat.
This pulsing operation of the STEP Warmfloor™ system is designed to prevent overheating of the zone. Also, this pulsing
operation prevents the zones air temperature from reaching the programmed set point. The zones maximum air
temperature will be a few degrees below the programmed set point as is represented above in Figure B. Adjusting the set
point up a few degrees higher than the desired air temperature will compensate for this difference. It is intended that the
maximum zone temperature is a few degrees below the set point to prevent the DIGI-LUX from de-energizing the STEP
Warmfloor™ system for a long time duration, resulting in a significant drop in radiant energy into the zone and a drop in
system efficiency. The DIGI-LUX maximizes the efficiency of the STEP Warmfloor™ system by only requiring the system
to gently replace the heat that is lost from the zone.
Important Note for Floor Warming Systems: The DIGI-LUX is designed for total heating applications and only calls for
the amount of heat necessary to heat the space. Consequently, the floor may not feel noticeably warm to the touch. If a
DIGI-LUX is used to control a floor warming system, it may be necessary to program the DIGI-LUX set point to a
temperature that is at least 3 to 5°F higher than the set point on your primary heat system thermostat to prevent your
primary heat system from de-energizing the floor warming system for long durations.
Installation
The process of installing the DIGI-LUX involves preplanning of mounting locations and roughing in of the necessary
hardware. The installation of the DIGI-LUX typically occurs during new construction or a remodel project where access to
the walls is possible for the rough in work. If access to the walls is not possible, as during some remodel projects, the
DIGI-LUX installation may require the use of surface mounted raceway products such as those manufactured by
Wiremold® (www.wiremold.com).
Plan mounting
locations Thermostat – Locate the thermostat approximately 60” off the floor in a location that is most
representative of the zone that it controls. Do not install where exposed to direct sunlight or
drafts.
Regulator – The regulator is typically located adjacent to the low-voltage transformer(s) that it
controls. The regulator, along with the transformer(s), are air cooled devices and need to be
mounted in a well ventilated area.
Programmed Set point
Measured Air Temperature
Pulse On
Pulse Off

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Rough in
The thermostat is designed to be flush mounted on a single gang junction box. Install such a
box at the desired mounting location.
The regulator is supplied mounted to the cover in a surface mounted junction box. Remove the
cover with the regulator attached and mount the supplied junction box at the desired mounting
location.
Install the supplied 4-conductor cable between the thermostat junction box and the regulator
junction box. The cable can be installed in the wall without the use of conduit as it only carries a
low voltage signal. If the cable is not long enough, acquire a suitable length of an equivalent
cable sufficient to run the full length between the boxes. Do not splice the cable – only use a full
new length. If an additional regulator will be connected, install the supplied 4-conductor cable
between the regulators.
Regulator
Connect the line voltage wires from the service panel and the transformer(s) to the regulator as
shown in Figure C. Use solid or low strand count wire as typically found in NM cable. Terminate
the 4-conductor cable to the regulator ensuring that the drain wire from the shield is connected
to the line voltage ground. Push the excess wire and cable into the box and install the cover.
Repeat the same process for each additional regulator connected to the same thermostat using
the wiring diagram in Figure C.
Thermostat
Terminate the 4-conductor cable to the thermostat as shown in Figure C. Trim back the shield
flush with the outer cable jacket and do not ground the drain wire at the thermostat. Only ground
the drain wire at the regulator. Remove the trim piece from the Thermostat to expose the
mounting holes. Push the excess cable into the box and install the Thermostat using the screws
provided. Reinstall the trim piece over the Thermostat.
Figure C
DIGI-LUX Wiring Diagram
Note: For Add-On Regulator (Model # DIGI36-1), the
“V-“ terminal may be labeled “V+” and is to be
connected via the “V+” terminals on each regulator

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Operation
Normal Operation The DIGI-LUX digital display indicates the measured room temperature during normal
operation.
Set-point change
The set-point is modified by using the Settings Button (See Figure A) located on the
thermostat faceplate. The first press of the Settings Button will cause the digital display
intensity to increase and to display the present set-point. The set-point can be changed by
repeatedly pressing the Settings Button until you reach the desired setting. The set-point
choices are displayed in a scrolling loop that runs from 36°F to 85°F. When you reach
85°F, the loop wraps back around to 36°F. After a few seconds of inactivity, the digital
display will dim back to its original intensity and will return to displaying the measured room
temperature.
Initial Setup
After the STEP Warmfloor system has been in operation for 2-6 days and the zone
temperature has stabilized, it is recommended to verify the displayed air temperature
against a trusted air thermometer. The thermostats self generated heat in addition to other
influences from its mounting location may cause the displayed temperature to be off by a
few degrees.
The displayed ambient temperature can be modified up or down 3°C through the use of the
Settings Button and a jumper on the back of the thermostat. Turn to the Off Set instructions
in the Additional Functions section of this manual for additional information.
Additional
Functions
Through the use of the Settings Button and a series of jumpers on the back of the
thermostat, additional functions can be accessed. Refer to the Additional Functions section
of this manual for a detailed description of these functions.
Temperature units – allows you to select between °F or °C for the temperature display. The
DIGI-LUX is shipped with °F set by default.
Auto Dim – allows you to increase the digital display intensity to full brightness during
normal operation. The DIGI-LUX is shipped with the display dimmed during normal
operation.
Offset – allows you to adjust the displayed temperature up or down 3°C to compensate for
the actual conditions at the thermostat installation location.
Additional Functions
The DIGI-LUX is provided with the ability to modify a few additional operating
functions besides the set-point. These Additional Functions are accessed
through the use of the Settings Button and a series of jumpers on the back of the
thermostat. Refer to Figure D for jumper locations.
The additional functions are:
•Temperature units – allows you to select between °F or °C for the
temperature display. The DIGI-LUX is shipped with °F set by default. This
function is changed using jumper J2.
•Auto Dim – allows you to increase the digital display intensity to full
brightness during normal operation. The DIGI-LUX is shipped with the
display dimmed during normal operation. This function is changed using
jumper J3.
•Off Set – allows you to adjust the displayed temperature up or down 3°C to
compensate for the actual conditions at the thermostat installation location.
This function is changed using jumper J1.
Jumper J0 has no function other than to serve as a storage location for a jumper
removed from one of the other jumper positions.
V+
V-
SYNC
TRIG
TERMINALS
JUMPERS
J3 J2 J1 J0
Figure D
Back of DIGI-LUX Thermostat

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Temperature Units
The DIGI-LUX is shipped configured to display temperatures in Fahrenheit. If a temperature display in Celsius is desired,
remove the jumper installed in position J2. You can store this spare jumper in position J0.
To access the jumper, remove the trim piece around the thermostat to expose the mounting screws. Remove the
mounting screws and gently pull the thermostat away from the mounting box. The jumper is located on the back of the
thermostat. Refer to Figure D for the exact location of jumper J2.
Upon removal of the jumper, push the excess signal cable into the box and re-install the thermostat using the screws
provided. Reinstall the trim piece over the Thermostat.
Auto Dim
The DIGI-LUX is shipped configured for the display intensity to be dimmed during normal operation. The display intensity
will increase when the Settings Button is depressed. After a few seconds of inactivity, the digital display will dim back to its
original intensity.
The display intensity can be increased to a constant intensity during all operating modes by removing the jumper in
position J3. You can store this spare jumper in position J0.
To access the jumper, remove the trim piece around the thermostat to expose the mounting screws. Remove the
mounting screws and gently pull the thermostat away from the mounting box. The jumper is located on the back of the
thermostat. Refer to Figure D for the exact location of jumper J3.
Upon removal of the jumper, push the excess signal cable into the box and re-install the
thermostat using the screws provided. Reinstall the trim piece over the Thermostat.
Offset
After the STEP Warmfloor system has been in operation for 2-6 days and the zone temperature has stabilized, it is
recommended to determine the offset between the displayed ambient temperature and the actual room temperature. Due
to the installation location (inside wall vs. outside wall, etc.) and the tolerance of the thermostat components, the
thermostat’s displayed ambient temperature could be a few degrees different from the actual room temperature.
Removing this offset from the thermostat will help to ensure the maximum personal comfort in each zone and add to the
systems energy efficiency. The displayed ambient temperature can be offset up or down 3°C through the use of the
Settings Button and jumper J1 on the back of the thermostat.
Follow these step-by-step instructions to modify the offset of the thermostat.
STEP 1:
Secure a reasonably accurate air measuring thermometer. Place it adjacent to the DIGI-LUX
thermostat for about 30 minutes to allow it to reach a steady temperature.
STEP 2:
Record the temperature displayed on the DIGI-LUX thermostat and the air measuring
thermometer on the Figure E worksheet. Refer to Chart A to convert the two temperature
readings into Celsius. Subtract the DIGI-LUX temperature from the Actual Air temperature and
record the result in the °C Offset box. Include a minus sign if this number is a negative number.
If the Offset is +/- 1°C or more, then continue on to STEP 3. If the Offset is less than +/-1°C,
then adjusting the offset is not necessary so do not continue any further with the offset
adjustment procedure.
Actual Air
DIGI-LUX
°F °F
Convert to Celsius (Chart A)
°C - °C =
°C Offset
Figure E
Offset Calculation Worksheet
Chart A
80 26.7
79
°C°F 18.365
66
67
68
69
70
71
72
73
74
75
76
77
78
18.9
19.4
20.0
20.6
21.1
21.7
22.2
22.8
23.3
23.9
24.4
25.0
25.6
26.1

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STEP 3:
Remove the trim piece around the thermostat to expose the mounting screws. Remove the mounting screws and gently
pull the thermostat away from the mounting box.
STEP 4:
Access the offset function by installing a jumper in position J1. Borrow the jumper located in position J3 and
install it into position J1. If position J3 does not have a jumper installed, then you should find it stored in
position J0. Refer to Figure D for the exact location of jumpers J3, J1 and J0.
Installing the J3 jumper into position J1 will cause the display intensity to increase and change to the offset
display to read 00.
PLEASE NOTE: The offset display is a looping display that runs from 0.0 through 3.0 to –0.0 through –3.0
(see Figure F). The decimal point is inferred as it is not displayed. For negative values, the minus sign will
appear in the Temperature Unit display window (see Figure A).
STEP 5:
Press the Settings Button to scroll through the offset display until you reach the calculated offset value.
Remove the temporary jumper installed in position J1 and return the jumper to its original position (J3 or J0).
STEP 6:
Push the excess signal cable into the box and re-install the thermostat using the screws provided. Reinstall
the trim piece over the Thermostat.
Product Specifications
Refer to the DIGI-LUX data sheet for more comprehensive information
Thermostat
Set point range 36°F to 82°F (2°C to 28°C)
Temperature Display 2-digit LED indicates air temperature in Operating Mode and set point in
Program Mode. Single digit LED indicates engineering units (°F or °C)
Faceplate Color White
Regulator
Supply Voltage 120 or 240Vac
Load Rating 2,500 Watts
Terminal Wire Sizes #14 - #10 AWG solid copper or aluminum
#8 - #6 AWG stranded copper or aluminum
Enclosure NEMA 1
Max. Ambient Temperature
and Conditions 104°F (40°C), well ventilated space
Signal Cable 4 Conductor #24 AWG Shielded (Belden #9534 or eq.)
Ordering Information
Description Model Number App. Wt.
DIGI-LUX™Thermostat / Regulator combination, 120Vac,
2,500W DIGI-LUX-120V 2.8 Lbs.
DIGI-LUX™Thermostat / Regulator combination, 240Vac,
2,500W DIGI-LUX-240V 2.8 Lbs.
DIGI-LUX™Add-on Regulator, 120Vac, 2,500W DIGI-REGULATOR-120V 2.6 Lbs.
DIGI-LUX™Add-on Regulator, 240Vac, 2,500W DIGI-REGULATOR-240V 2.6 Lbs.
Approvals
CUS Conforms to ANSI/UL STD 1693
Certified to CAN/CSA-C22.2 No. 217
EN60335-1: 1995
EN60355-2-30: 1997
Figure F
0.0
0.1
2.9
3.0
-3.0
-2.9
-0.1
-0.0