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REMOVING THE OLD THERMOSTAT:  
1. Switch OFF the electricity to the heating/cooling equipment; then  
proceed with the following:  
FRONT PANEL ITEMS  
Complete, Easy To Read  
SYSTEM MODE SWITCH:  
INSTALLATION AND OPERATING INSTRUCTIONS  
2. Remove the front cover from your old thermostat. Most will  
simply pull straight off, while others may be fastened by screws.  
3. Take note of the letters printed near each of the wire terminals.  
Attach adhesive labels (enclosed) to each wire for identification by  
their terminal letter, not the color of the wire.  
4. Make sure the wires do not fall back inside the wall. Remove and  
label each wire one at a time, and do not allow the wires to touch  
each other or any parts of the thermostat.  
The MODE switch has 4 positions: EMER, HEAT, OFF, and COOL. In  
the summer, set the switch to COOL to control cooling. In the  
winter, set the mode switch to HEAT to control heating; set the mode  
switch to EMER to control auxiliary heating only (if equipped). In  
the EMER position, the heat pump compressor is disabled. When set  
to OFF mode, the heating and cooling system will remain off.  
DHP2120  
BATTERY POWERED, NON-PROGRAMMABLE  
DIGITAL HEAT PUMP THERMOSTAT  
FAN MODE SWITCH:  
The FAN switch has 2 positions: AUTO and ON. In the AUTO  
position, the operation of the blower fan is determined only by the  
on/off cycling of the heating and cooling system. In the ON position,  
the system's blower fan will be commanded ON continuously at all  
times, even when the system mode switch is in the OFF position.  
5. Loosen all screws on the old thermostat base, and remove it from  
the wall.  
52068  
LUX PRODUCTS CORPORATION  
MOUNTING THE NEW THERMOSTAT:  
1. Strip insulation leaving approximately 3/8 in. (10mm) of bare wire  
on the ends, and clean off any corrosion present.  
2. Fill the wall opening with non-combustible insulation to prevent  
drafts from affecting the thermostat while in use.  
3. Pull your new thermostat apart by applying pressure to the thumb  
tab on the bottom edge of the unit, while pulling the front and  
back halves apart from the bottom edge of the thermostat.  
Mt. Laurel, New Jersey 08054, USA  
WARNING: Use Energizer® or DURACELL® Alkaline Batteries Only.  
Energizer® is a registered trademark of Eveready Battery Company, Inc.  
DURACELL® is a registered trademark of The Gillette Company, Inc.  
PUSH BUTTONS:  
There are two push buttons to the right of the unit's display screen.  
These are used to adjust the set point temperature.  
I M P O R T A N T !  
OPERATING INSTRUCTIONS  
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.  
TEMPERATURE ADJUSTMENT:  
NOTE: If you are mounting the base to a soft material like  
plasterboard, or if you are using the old mounting holes, the  
screws may not hold. Drill a 3/16-in (4.8mm) hole at each  
screw location, and insert the plastic anchors provided.  
While in HEAT, COOL, or EMER modes, a single press on either the  
UP or DOWN button causes the word “SET” to appear on the screen,  
and the set temperature value on the screen to start flashing. When  
flashing, the set temperature can be altered by pressing either the  
UP or DOWN button once per degree of change, or by holding either  
button for at least two seconds to automatically increment the set  
temperature quickly in the associated direction.  
Thank you for your confidence in our product. 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.  
4. Route the wires through the large hole adjacent to the terminal  
block, and hold the base plate against the wall. Position the base  
for best appearance, and to hide any marks from an old  
thermostat. Attach the base to the wall with the two screws  
provided.  
Based upon the relationship of the set temperature to the displayed  
ambient room temperature, the thermostat will engage the first stage  
of either heating or cooling, if a temperature demand is present.  
WIRING INFORMATION  
If there is a large thermal demand present which is greater than the  
first stage of heating can accommodate, then a second stage of  
heating (W2) will be activated, showing the word “AUX” on the  
display screen. There is approximately a 4-minute delay that is  
imposed between the activation of the first stage of heating, and the  
second stage of heating.  
COMPATIBILITY  
• The DHP2120 thermostat can be used with most 24 volt: single-  
stage heat pumps, and 2 heat / 1 cool heat pump systems.  
** Complete heating or cooling system wiring can be found in the  
WIRE IDENTIFICATION AND WIRING SCHEMATICS section of this  
instruction sheet. The schematics show system components for  
brand new installations or for un-referenced wires.  
• This thermostat cannot be used to control: conventional heating  
and cooling systems, 3-wire zone valves, or 120/240 volt (line  
voltage) heating or cooling systems. Ask your dealer for other  
LUX® thermostats to control those systems.  
CONNECTING THE WIRES:  
DISPLAY ILLUMINATION:  
Pressing either set temperature button will illuminate the display.  
The light will remain on for approximately 12 seconds. While the  
light is illuminated, pressing any of the 2 push buttons will cause the  
light to remain on for approximately 12 more seconds.  
5. Clean bare wire ends must be inserted in between the  
black clamp and the brass terminal as shown here.  
6. Securely tighten all electrical terminal screws  
(even unused ones).  
FEATURES  
MINIMUM RUN/OFF TIME:  
Quick & Easy  
Temperature  
Change  
This is determined by the thermostat, and controls the minimum  
length of time that the thermostat must remain with Heat or Cool  
either On or Off, before it will automatically switch to the alternate  
On or Off state. This feature prevents rapid or short cycling, and  
also provides compressor protection. The duration of this delay is  
fixed at 5 minutes between on or off load changes.  
SETUP OPTIONS  
If batteries are presently installed, remove them from the thermostat  
before proceeding with changing any of the options listed below. A  
table similar to this one shown here is printed on the thermostat's  
circuit board.  
Buttons  
˚
72  
Fan  
Slide  
Switch  
ADJUSTABLE TEMPERATURE STOPS:  
Large Easy to  
Read Backlit  
Display  
FAN  
There are two independent set temperature stops: a maximum heat  
set temperature, and a minimum cool set temperature. Each of these  
temperature stops is user adjustable in one-degree increments. The  
heat temperature stop prevents the set temperature from being  
adjusted higher than the heat temperature stop value. The cool  
temperature stop prevents the set temperature from being adjusted  
lower than the cool temperature stop value.  
UP  
DOWN  
AUTO  
ON  
Mode  
Slide  
Switch  
EMER  
HEAT  
OFF  
JP1 (SCALE)  
JP2 (B / O)  
F
B
C
O
COOL  
To set the heat and cool temperature stops, place the system mode  
switch in the OFF position. Press and hold the UP key while sliding  
the mode switch from either OFF to HEAT (to adjust the maximum  
heat set temperature), or from OFF to COOL (to adjust the minimum  
cool set temperature). “Ht Lim” or “Cl Lim” will be displayed on the  
LCD screen while you are setting the heat or cool limits respectively.  
While in the adjustment mode for each of the temperature stops, use  
the UP and DOWN buttons to adjust the limit value, just as you  
would for adjusting the set temperature under normal operation.  
JUMPER SETTINGS:  
There are 2 option jumpers located inside the thermostat on the  
circuit board. These settings can be changed from their default  
values by removing its corresponding black shorting cap and  
installing the cap so that it is positioned on the adjacent pair of  
metal pins. A change to either of the option jumpers will not be  
recognized unless the thermostat has been without battery power for  
at least 2 minutes, and then power is restored again. Each of these  
jumpers changes a different setup option. The choices for these  
options are listed in a table printed on the circuit board, and are also  
printed adjacent to each individual setting jumper.  
Digital, Non-Programmable  
Battery Powered Only  
Easy To Install  
F / C Selectable Temperature Display  
Fixed 5 Minute Minimum Run /  
Off Time For Compressor Protection  
Adjustable Temperature Stops  
Set Temperature Range 45°F to 90°F  
Clean, Attractive Design  
Large, Easy To Read Display with  
LED Backlight  
NOTE: If no buttons are pressed for 4 seconds, the thermostat will  
accept the limit value that was on the screen, and return to normal  
operating mode, for the current mode switch position. Once,  
complete, you should return to the adjustment mode again for both  
heat and cool to confirm your desired settings for both temperature  
modes have been accepted.  
INSTALLATION  
PLEASE READ ALL INSTRUCTIONS CAREFULLY BEFORE BEGINNING  
INSTALLATION.  
JP1 - FAHRENHEIT OR CELSIUS DISPLAY FORMAT:  
This setting controls whether the temperature is  
F
JP1  
JP2  
shown in degrees °F or °C on the LCD display  
screen.  
C A U T I O N :  
C
BATTERIES AND MAINTENANCE  
This thermostat is protected against normal static electric  
discharges. However, in extremely dry weather you should  
touch a grounded metal object before touching the thermostat  
to minimize the risk of causing damage to the unit.  
The batteries in the thermostat should be replaced AT LEAST once  
per year, or sooner if the “LO BAT” battery symbol appears in the  
lower right portion of the display screen.  
JP2 - [B] OR [O] TERMINAL USAGE OPTION:  
This setting determines how the thermostat will use  
the shared B/O terminal connection on the back  
plate. Select the “B” option to have the B/O  
terminal powered while in heat mode, and un-  
powered while in cool and off modes. Select the  
“O” position to have the B/O terminal powered while  
in cool mode, and un-powered while in heat and off  
modes. If you are not sure which way to set this  
option, consult the manufacturer of your heat pump  
unit.  
B
O
To replace the batteries in the thermostat, remove the thermostat’s  
body from the wiring base plate attached to the wall by pressing the  
thumb latch at the bottom center of the unit and swinging the front  
body out towards you, up and away from the base. Remove the used  
batteries from the battery tray and discard appropriately.  
TOOLS REQUIRED:  
• #1 Phillips screwdriver (small - medium)  
• Drill with 3/16-in. (4.8mm) drill bit  
• Wire stripper/cutter  
Install two new Energizer® or DURACELL®, “AA” size Alkaline  
batteries into the battery tray. Observe the polarity markings shown  
in the battery compartment to ensure proper installation. When  
finished, hang the top of the unit by the tabs at the top corners of  
the base, and then snap the bottom of the unit into place. Do not  
use unnecessary force. If the body does not snap into place easily,  
remove the body, re-hang it from the tabs at the top and try again.  
C A U T I O N :  
Turn off electricity to the appliance before  
installing or servicing the thermostat or any part  
of the system. Do not turn the electricity back  
on until the work is completed.  
Once all optional jumper settings have been performed as described  
in the previous section, ensure that the thermostat has been without  
battery power for at least 2 minutes for the change to be recognized.  
Now install new batteries into the thermostat. When installing  
batteries, use two new Energizer® or DURACELL® “AA” size alkaline  
batteries only. Ensure that the batteries are installed in the proper  
direction as per the markings shown in the battery tray.  
Your thermostat is a precision instrument. Please handle it with  
care.  
TECHNICAL ASSISTANCE  
Do not short (jumper) across the electric terminals on your  
heating or cooling equipment to test the system. This may  
damage the thermostat and void your warranty.  
All wiring must conform to all applicable local codes and  
ordinances.  
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  
COMPLETING THE INSTALLATION  
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  
the most common technical questions, and also permits you to email  
your questions to our technical support staff at your convenience.  
Install your new thermostat onto its base. To do this, start with the  
bottom tilted out towards you at first, and line up the two holes in  
the top of the thermostat with the two hooks on the top of the back  
plate. Slowly pivot the bottom of the thermostat towards the back  
plate and push firmly on the bottom half of the thermostat until it is  
securely latched to the back plate. If the two thermostat halves do  
not mate together easily, remove and try again. Do not attempt to  
force them together if they do not appear aligned properly.  
This thermostat is limited to a maximum of 1.5 amps, total  
current; higher current may cause damage to the thermostat.  
THERMOSTAT 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, at about 5 ft. (1.5m)  
above the floor, and in a room that is used often.  
2. Do not install it where there are unusual heating conditions, such  
as: direct sunlight, near a lamp, television, radiator, register,  
fireplace, on a wall opposite a stove, or that carries hot water  
pipes.  
3. 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.  
4. Do not locate where air circulation is poor, such as: in a corner or  
alcove, or behind an open door.  
WARRANTY  
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 "Technical  
NOTE: Before use, remove the plastic film (if present) that is  
protecting the LCD display screen.  
Turn the electrical power back ON to both your heating and/or  
cooling systems. Verify that both systems are operating properly.  
When set to a high temperature, the heating system should provide  
warm air after a short time in Heat Mode. Likewise, the cooling  
system should provide cool air after a short time when set to a low  
temperature in Cool Mode. Usually, sound from the heater and/or  
cooling system units can be heard while either is running. Your  
installation is now complete.  
ASSISTANCE" before returning thermostat. Purchaser assumes all  
risks and liability for incidental and consequential damage resulting  
from installation and use of this unit. 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 only.  
5. Do not locate in a damp area. This can lead to corrosion that may  
shorten thermostat life.  
6. Do not install the unit until all construction work and painting has  
been completed.  
©
2 0 0 8 L U X P R O D U C T S C O R P O R AT I O N . A L L R I G H T S R E S E R V E D  
href="
HEAT PUMP TERMINAL CROSS REFERENCE CHART  
(DHP2120) ENGLISH - WIRE IDENTIFICATION AND WIRING SCHEMATICS  
TABLEAU DE RÉFÉRENCE CROISÉE DE BORNE DE POMPE À CHALEUR  
TABLA DE REFERENCIA PARA LA TERMINAL DE LA BOMBA DE CALEFACCIÓN  
HEAT PUMP BRAND  
CORRESPONDING TERMINALS  
TAPE OFF (NOT USED)  
TYPICAL 24 VOLT, SINGLE-STAGE HEAT PUMPS AND  
2-STAGE HEAT / 1-STAGE COOL HEAT PUMP SYSTEMS  
WITH NO EMERGENCY HEAT WIRE  
TYPICAL 24 VOLT, 2-STAGE HEAT / 1-STAGE COOL  
HEAT PUMP SYSTEMS  
# 1  
# 2  
MARQUE DE POMPES  
À CHALEUR  
BORNES  
CORRESPONDANTES  
RUBAN RETIRÉ  
(NON UTILISÉ)  
WITH EMERGENCY HEAT WIRE PRESENT  
MARCA DE LA BOMBA  
DE CALEFACCIÓN  
TERMINALES  
CORRESPONDIENTES  
DESPRENDIMIENTO  
(NO UTILIZADO)  
Y1  
E
G
R
B/O Y2 W2  
C
Y1  
E
G
R
B/O Y2 W2  
C
E
G
Y
R
O
W2  
B
C
L
ARCO / Friedrich  
ARCO / Snyder General  
BARD  
X2  
G
G
G
G
G
G
G
G
G
G
G
G
F
Y
Y
RC  
R
W2  
W1  
W2  
W2  
W1  
Y1  
W2  
W2  
W2  
W
B
C
L
X
L
L
F
L
L
L
**Refer To  
E
O
C
Wiring Note #1  
E
Y1  
Y
R
B
X
System  
System  
Common  
BARD, HP, WH, MHP, HPQ  
BDP / BRYANT  
E
R
W1  
X
Common  
E
E
Y
R
O
O
O
O
V
C
+
+
-
-
CARRIER  
Y
R
C
HEAT  
BLOWER  
FAN  
SYSTEM  
XFMR  
REVERSING  
VALVE  
AUX.  
HEAT  
HEAT  
PUMP  
EMERGENCY  
HEAT  
BLOWER  
FAN  
SYSTEM  
XFMR  
REVERSING  
VALVE  
AUX.  
HEAT  
CARRIER 5Q  
to W2  
E
Y, W1  
Y
R
C
PUMP  
CARRIER 50Q, QT382  
COLEMAN  
R
C
Y
RED  
R
BLACK  
GE BAY  
X2  
E
Y
O
O
O
R
R
R
R
O
B
B
T
HEIL-QUAKER / Whirlpool  
JANITROL / Goodman  
LENOX TYPICAL HP6  
LENOX HP8  
Y
R
W
Y
R
W2  
Y
C
X
(DHP2120) FRENCH - SCHÉMAS D'IDENTIFICATION DES FILS ET DU CÂBLAGE  
M
M
M
M
Y
V/VR  
V/VR  
V/VR  
V/VR  
R
E
E
E
E
E
F
Y
X
LENOX HP9, 10  
LENOX HP16, 18, 19  
MAGIC CHEF PE  
RHEEM / RUUD  
SNYDER GENERAL H-R811  
TRANE  
F
Y
X
L
L
LES POMPES À CHALEUR À UN ÉTAGE TYPIQUES DE 24 VOLTS  
ET LES SYSTÈMES DE POMPE À CHALEUR À 2 ÉTAGES DE CHALEUR /  
1 ÉTAGE DE REFROIDISSEMENT SANS FIL DE CHAUFFAGE D'URGENCE  
LES SYSTÈMES DE POMPES À CHALEUR À  
N° 1  
N° 2  
F
Y
X
UN ÉTAGE DE REFROIDISSEMENT / 2 ÉTAGES DE CHAUFFAGE  
TYPIQUES DE 24 VOLTS AVEC UN FIL DE CHAUFFAGE D'URGENCE  
G
G
G
G
G
G
G
G
F
W
C
X
Y
R
W2  
W1  
W
B
L
F
Y
R
O
O
C
B
Y1  
E
G
R
B/O Y2 W2  
C
Y1  
E
G
R
B/O Y2 W2  
C
X2  
Y
R
T
WEATHERKING  
WESCO  
W1  
W1  
W1  
Y
R
Y1  
Y1  
O
E
C
C
X
E
E
E
R
W2  
** Reportez-vous à la note  
de câblage numéro 1  
WESCO / ADDISON  
WESTINGHOUSE H50  
WESTINGHOUSE HE  
WHITE RODGERS  
YORK  
R
R
O
W
H2  
W2  
W
X
L1  
Système  
commun  
Système  
commun  
C
V/VR  
R
Z
X
E
G
G
Y
O
O
C/X1  
B
L
X
+
+
Y
R
-
-
POMPE À  
CHALEUR  
VENTILATEUR  
SOUFFLANT  
SYSTÈME  
XFMR  
ROBINET  
INVERSEUR  
AUX.  
CHALEUR  
POMPE À  
CHALEUR  
CHAUFFAGE  
D'URGENCE  
VENTILATEUR  
SOUFFLANT  
SYSTÈME  
XFMR  
ROBINET  
INVERSEUR  
AUX.  
CHALEUR  
WIRING DIAGRAM NOTES:  
1. The DASHED lines in wiring diagram #1 are optional depending upon your system type. Single stage heat pumps will not have wires  
present for the “E” or “W2” terminals. For a 2-Heat / 1-Cool system with NO Emergency heat wire, AUX heat will be connected to  
“W2”. A jumper wire may be placed in between the “E” and “W2” terminals to allow Emergency Heat Mode.  
2. For Heat Pumps, use either the “B” or “O” wire, NOT BOTH.  
(DHP2120) - IDENTIFICACIÓN DE CABLES Y DIAGRAMAS DE CABLEADO  
3. If “Y” and “C” wires are both present, then “C” is a common wire. Do not connect this “C” wire to your thermostat.  
4. If you have a “B” wire in your system that is used as a common wire, connecting it to the “B/O” terminal on this thermostat may  
damage your system and/or the thermostat.  
NOTES DU DIAGRAMME DE CÂBLAGE :  
BOMBAS TÍPICAS DE CALEFACCIÓN DE UNA FASE Y SISTEMAS  
TÍPICOS CON BOMBA DE CALEFACCIÓN DE 2 FASES  
Y AIRE ACONDICIONADO DE 1 FASE, TODOS DE 24 VOLTIOS  
SISTEMAS TÍPICOS CON BOMBA DE CALEFACCIÓN DE 2 FASES  
Y AIRE ACONDICIONADO DE 1 FASE DE 24 VOLTIOS,  
CON CABLE DE CALEFACCIÓN DE EMERGENCIA  
#1  
#2  
1. Les lignes en TRAITS TIRÉS du diagramme de câblage 1 sont optionnelles et leur utilisation dépend de votre type de système. Les  
pompes à chaleur à un étage n'ont pas de fils pour les bornes « E » ou « W2. » Pour un système à 2 chauffage / 1 refroidissement  
SANS fil de chauffage d'urgence, la chaleur AUX sera branchée à « W2 ». Un fil de calier peut être placé entre les bornes « E » et  
« W2 » pour permettre l'utilisation du mode de chau ffage d'urgence.  
2. Pour les pompes à chaleur, utilisez soit le fil « B » ou « O », NON PAS LES DEUX.  
3. Si vous avez les fils « Y » et « C », alors le « C » est le fil commun du système. Ne branchez pas ce fil « C » à votre thermostat.  
Y1  
E
G
R
B/O Y2 W2  
C
Y1  
E
G
R
B/O Y2 W2  
C
4. Si vous avez un fil « B » dans votre système et si ce fil est utilisé comme fil commun, le brancher à la borne « B/O » du thermostat  
pourrait endommager votre système et/ou le thermostat.  
**Consulte la Nota  
de cableado #1  
NOTAS DEL DIAGRAMA DEL CABLEADO:  
1. Las líneas PUNTEADAS en el diagrama del cableado #1 son opcionales, dependiendo del tipo de sistema. Las bombas de  
calefacción de una fase no contienen cables para las terminales “E” ni “W2”. Para un sistema de 2 fases de calefacción y una de  
enfriamiento, NO se conecta el cable de calefacción de emergencia ni el auxiliar (AUX) en la terminal “W2”. Puede colocar un  
cable para formar un puente entre las terminales “E” y “W2” y permitir un modo de calefacción de emergencia.  
Sistema  
Común  
Sistema  
Común  
+
+
-
-
2. Para las bombas de calefacción, utilice el cable “B” o el cable “O”, NUNCA USE AMBOS.  
BOMBA DE  
CALEFACCIÓN  
SISTEMA  
XFMR  
VÁLVULA DE  
INVERSIÓN  
CALEFACCIÓN  
AUX.  
BOMBA DE  
CALEFACCIÓN  
CALEFACCIÓN DE  
EMERGENCIA  
SISTEMA  
XFMR  
VÁLVULA  
DE INVERSIÓN  
CALEFACCIÓN  
AUX.  
3. Si tanto el cable “Y” como el “C” están presentes, entonces es más probable que el “C” sea el cable común del sistema. No  
conecte el cable “C” a su termostato.  
VENTILADOR  
VENTILADOR  
4. Si en su sistema hay un cable “B” que se utiliza como cable común, no lo conecte a la terminal “B” ni “O” del termostato, pues  
podría dañar tanto su aparato como su sistema.