Wall / Trim Plate
EcoStat THC15a Heating & Cooling
Mercury FREE Manual Thermostat
LUX PRODUCTS CORPORATION
Mt. Laurel, New Jersey 08054, USA
9. Insert the two longer mounting screws provided through the right and left Trim Plate screw holes
and thread each screw into the mounting holes into the wall or the plastic screw anchors.
10. Carefully push all excess wire back into the wall. Align the thermostat sub-base with the
decorative wall plate by using the 3 alignment pins and holes molded into the back of the
subbase and Trim Plate. Attach the Sub-Base to the Trim Plate using the two smaller mounting
screws provided. Thread these two small screws into the single inner holes in the Trim Plate.
11. Now that the Sub-Base is mounted, align the front portion of the thermostat with the Sub-Base
using the Light Button and the cutout for it in the Sub-Base. While holding the thermostat in
place against the Sub-Base, carefully and evenly tighten the 3 silver captive screws that are held
in place inside the front of the thermostat assembly.
Please read all instructions carefully before beginning installation and save for future
reference. Before removing any wiring from your existing thermostat, the wires must
be labeled with their terminal designations. Ignore the color of the wires since they
may not comply with any standard.
Thank you for your confidence in our product. To obtain the best results from your investment,
please read these instructions thoroughly. You should become fully acquainted with this thermostat
before installing it for usage. Follow the installation procedures carefully, and one step at a time.
This will save you time and minimize the chance of damaging either the thermostat or the systems
that it controls. These instructions may contain information beyond that required for your particular
installation. Please save these instructions for future reference.
** Complete heating and/or cooling system wiring can be found in the WIRE IDENTIFICATION AND
WIRING SCHEMATICS section of this instruction sheet. The schematics shown provide component
information for brand new installations or for unreferenced wires.
This mechanical thermostat can be used with most single-stage 24 volt gas, oil, or electric heating
and air conditioning systems. It cannot be used with heat pumps, 3 wire zone valves, line voltage
(120/240 volt) heating systems, or Millivolt systems. Ask your dealer for other LUX thermostats to
control those systems.
The only item that will need to be tailored to your
system is the Heat Anticipator. This setting is for
heating systems only. If you are using this
thermostat on a “cooling only” system with no
heater, the Anticipator does not need to be set and
can be left as is.
• Push Button Back Light
• Glow-In-The-Dark Dial Numbers
• Soft Rubber Set Temperature Ring
• Large Easy To Use Mode Switches
If you are replacing an old mechanical thermostat,
find the Anticipator setting on the old thermostat,
and set the new thermostat to the same value. Do this by carefully sliding the silver metal pointer,
shown here, over desired number printed on the Anticipator scale. If an old Anticipator setting
cannot be determined, look on the gas control valve on your furnace, and find either the Anticipator
Value or a Current Rating. This will be the value to use for the Anticipator setting. If you cannot find
either of these numbers, set it to .6 initially to start with. During heating season, your furnace
should operate about five times an hour. If adjustments are necessary, move heat anticipator pointer
slightly and recheck. A lesser value will cause your heater to cycle more frequently, and a larger
value will cause it to cycle less frequently.
There are two mode switches on the front, a Temperature mode switch and a Fan mode switch. The
Temperature mode switch has three positions: HEAT, OFF, and COOL. In the winter, set the system
switch to HEAT to control your heating system. In the summer, set the switch to COOL to control
your air conditioner. In the spring and fall or when the windows are open, you can set the switch
OFF. The Fan mode switch has two positions, AUTO and ON. Setting the Fan mode switch to AUTO,
automatically runs your system's blower fan as required only during heating and cooling activation.
Setting the Fan mode switch to ON, runs your system’s fan continuously, even if heating or cooling is
not needed, including when the Temperature mode switch is in the OFF position to provide air
circulation only. In either HEAT or COOL mode, turn the front thermostat dial to the desired
US Patent USP D471,572
SELECTING A LOCATION
On replacement installations, mount the new thermostat in place of the old one unless the conditions
listed below suggest otherwise. On new installations, follow the guidelines listed below.
1. Locate the thermostat on an inside wall, about 5 ft. (1.5m) above the floor, and in a room that is
2. Do not locate where air circulation is poor, such as in a corner or an alcove, or behind an open
3. Do not install it where there are unusual heating conditions, such as: in direct sunlight; near a
lamp, television, radiator, register, or fireplace; near hot water pipes in a wall; near a stove on the
other side of a wall.
4. Do not locate in unusual cooling conditions, such as: on a wall separating an unheated room; or in
a draft from a stairwell, door, or window.
This thermostat has an illuminated panel to assist in reading the temperature while in low light
conditions. While in HEAT or COOL mode, press and hold the button on the top of the thermostat.
The backlight will not operate while the thermostat is in OFF mode.
5. Do not locate in a damp area. This can lead to corrosion that may shorten thermostat life.
6. If painting or construction work has yet to be completed, cover the unit completely or do not
If you have any problems installing or using this thermostat, please carefully and thoroughly review
the instruction manual. If you require assistance, please contact our Technical Assistance Department
at 856-234-8803 during regular business hours between 8:00AM and 4:30PM Eastern Standard Time,
Monday through Friday. You can also receive technical assistance online anytime day or night at
questions, and also permits you to email your questions to our technical support staff at your
• #1 Phillips screwdriver
• Drill with 3/16 in. (4.8mm) bit
• #1 Slotted screwdriver
• Wire Stripper / Cutter
NOTE: Review the type of wiring configuration that your system requires, prior to removing your old
thermostat or its wiring connections.
REMOVAL OF OLD UNIT
1. Turn OFF the electricity to all heating and cooling components. Do not turn the
electricity back on until all work is completed.
2. Remove the cover and front portion of your old thermostat to expose the wiring
3. Write down the letters printed near each wire terminal that is used, and the color of
the wire that is connected to it. Using the enclosed labels, attach a label to each of
your wires so that the letter matches the marking on your existing thermostat.
Limited Warranty: If this unit fails because of defects in materials or workmanship within three years
of the date of original purchase, LUX will, at its option, repair or replace it. This warranty does not
cover damage by accident, misuse, or failure to follow installation instructions. Implied warranties
are limited in duration to three years from the date of original purchase. Some states do not allow
limitations on how long an implied warranty lasts, so the above limitation may not apply to you.
Please return malfunctioning or defective units to the location from which the purchase was made,
along with proof of purchase. Please refer to
4. When they are all labeled, carefully remove the wires one at a time, making sure that they do not
fall back inside the wall. Do not allow any of the bare wire ends to touch each other, or any parts
on the thermostat.
"TECHNICAL ASSISTANCE" before returning
thermostat. Purchaser assumes all risks and
liability for incidental and consequential damage
resulting from installation and use of this unit.
5. Loosen all of the screws on the old thermostat and remove it from the wall.
Some states do not allow the exclusion of
incidental or consequential damages, so the
above exclusion 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. Applicable in the U.S.A. and Canada
1. Strip insulation leaving 3/8 in. (9.5mm) bare wire ends and clean off any corrosion.
2. Fill wall opening with non-combustible insulation to prevent drafts from affecting the thermostat.
3. The Wall/Trim Plate is optional, however its usage is recommended.
4. Remove the front trim ring from the thermostat by pulling it straight outwards.
5. If there are no existing mounting holes that are able to be reused, hold the Trim Plate level against
the wall with the “UP” markings up, and mark the “outer” two oval mounting holes on the right
and left. NOTE: if you are not using the Trim Plate, you can still mark the holes for the thermostat
using the two small inner holes on the right and left of the Trim Plate, which line up with the
thermostat mounting holes.
6. If you are mounting the base to a soft material like plasterboard, the screws alone may not hold.
Drill a 3/16 in. (4.8mm) hole at each screw location, and insert the plastic anchors provided into
the wall. If you are mounting to wood or similar substance, the screws may be used alone without
the plastic anchors.
7. First, feed the wires through the large middle hole in decorative wall plate (if used) and then
through the square lower hole near the bottom of the thermostat’s Sub-Base.
8. Referring to your earlier notes from removing your old thermostat, and the electrical diagrams in
this manual, attach the wires to the terminal screws. Make sure bare metal wires do not touch
each other. The wire connector screws on the Sub-Base may need to be loosened prior to
inserting any wires. When all wiring is complete, ensure that every screw is securely tightened.
© 2008 LUX PRODUCTS CORPORATION. ALL RIGHTS RESERVED