Gemtech GT5020 User manual

Install guide GT5020
Install guide GT5020

1 Location
Caution
Tools
To avoid electrical shock and to prevent damage to the furnace, air conditioner,
and thermostat, disconnect the power supply before beginning work.
This can be done at the circuit breaker, or at the appliance.
You will need #1 Phillips screwdriver (small) and
Drill with 3/16-in. (4.8mm) bit for this installation.
PG 1
Install guide GT5020
On replacement installations, mount the new thermostat in place of the
old one if possible.
On new installations, follow the guidelines listed below.
Locate the thermostat on an inside wall, about 5 ft. (1.5m) above the
floor, and in a room that is used often.
Do not install it where there are unusual heating conditions, such as: in
direct sunlight; near a lamp, radio, television, radiator register, or
fireplace; near hot water pipes in a wall; near a stove on the other side
of a wall.

C A U T I O N
Your thermostat is a precise instrument.
Please handle it with care.
Turn off electricity to the appliance before installing or
servicing thermostat or any part of the system. Do not
turn electricity back on until work is completed.
Do not short (jumper) across electric terminals at
control on furnace or air conditioner to test the system.
This will damage the thermostat and void your warranty.
All wiring must conform to local codes and ordinances.
This thermostat is designed for use with 24 volt AC and
millivolt systems.The thermostat should be limited to a
maximum of 1.0 amps; higher amperage may cause
damage to the thermostat.
This thermostat does not require leveling.
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.
Do not locate in a damp area.This can lead to corrosion that will shorten
thermostat life.
Do not locate where air circulation is poor, such as: in a corner or an
alcove; or behind an open door.
Do not install the unit until all construction work and painting has been
completed.
Good
5ft.
(1.5m)
PG 2

2 Remove old unit
IMPORTANT : LABEL ALL WIRES 
BEFORE DISCONNECTINGTHEM!
Switch electricity to the furnace and
air conditioner OFF;
then proceed with the following steps.
Remove cover from old thermostat.Most are snap-on types
and simply pull off. Some have locking screws on the side
or front.These must be loosened. Note the letters printed
near the terminals. Attach labels (enclosed) to each wire for
identification.
Label the wires one at a time. You must have all the wires labeled
before you proceed. With all wires labeled, remove them from the old unit.
Make sure the wires do not fall back inside the wall. Wind them around a
pencil to keep them from falling.
Loosen all screws on the old thermostat and remove it from the wall.
Fill wall opening with non-combustible insulation to prevent drafts. PG 3
B
G
W
Caution
Read instructions carefully before removing any wiring from existing thermostat.
Wires must be labeled before they are removed.THERE IS NO STANDARD
COLOR CODE. When removing wires from their terminals, ignore the color of the
wires since these may not match the letter.

3 Mount the GT5020
Separate front from back of unit. Press up on the
catch on bottom of thermostat and swing the body
away from the base, lift up to remove the body from
the base.
Hold the base against the wall, with the wires
coming through the opening below the terminal block.
Position the base for best appearance.
Attach the base to the wall with the two
screws provided.
If you are mounting the base to sheet rock
or if you are using the old mounting holes,
use the plastic anchors provided.Drill a
3/16-in.(4.8mm) hole for the insert at each
screw location, then mount the base.
PG 4
A
G
C
W2 RC
O
B
RH
WY
A
G
C
W2 RC
O
B
RH
WY
Terminal
Block
Thermostat Base

PG 5
4 Gas-Electric Selection
REFER to the back of the Control Unit
If you have Electric Heat or a Heat Pump you must place the Gas/Electric jumper in the ELECT
position (thermostat controls the Fan).
If you have Gas Heat the Gas/Electric Jumper should be in the GAS position (furnace controls
the Fan).
I f your heat pump has auxiliary
heat, select the DIFFERENTIAL
jumper. This controls how often
your auxiliary heat will come on.
'2' is most comfort (cold climates)
'4' is most efficient (warm climates)
The unit must be reset when a
jumper is changed.
5 Heat Pump Differential
Inside of Unit
GAS ELECT
AAAA AA
Fahrenheit
/Celsius jumper
Gas/Electric jumper
OFF ON
DIFFERENTIA 4
3
2
ADJ RM TEMP
Calibration switch
OPEN F SHORT C

6 Install Batteries
The GT5020 requires batteries to operate your system
and retain its programming in memory.
.
Switch MODE switch to OFF and the FAN switch to
AUTO.
.
Insert 2 AAalkaline batteries according to the
polarity noted in the compartment.
.
Press the RESET button to clear the transient
program memory. Initially, LCD display will go off.
NOTE: Replace the batteries when this LOW battery indicator appears on the display or once a year.
With batteries removed, you have approximately 30sec before your custom programming is lost.
7 Power Options
PG 6
Please be aware of the following power options
1) The GT5020 can run on batteries only. (2AAAlkaline)
The batteries will last well over 1 year. If the batteries are not replaced the thermostat
will stop working.
2) The GT5020 can run on the C wire if available. (24 VAC ONLY)
As shown in the wiring diagrams, The C wire is the other side of the 24VAC heating transformer. If the
C wire is used, the batteries are for AC power loss only and are not required.
AAAA AA

PG 7
Please refer back to these guidelines for safe and secure wire connections.
.
Take care not to damage the labels for each wire in handling.
.
Strip insulation 3/8 in. (9.5mm) from wire ends.
.
Connect labeled wires only to a terminal with corresponding letter.
.
Bend the wire slightly, insert the wire under the contact plate and tighten
the screw down onto the wire.
The Wire chart shows wire labels used on
Gemtech thermostats. Please determine what
wires you have and select the correct wiring
diagram to "go to" on pages 9.
Before you Connect Wires
What Wires Do You Have?
8 Wire Connections
Make sure your wires are labeled. This is necessary to determine which step-by-step wiring
diagram you should use. This may require you to find the 'other end' connection for each wire on
your heating or air conditioning equipment and read the label there.
If you have a Zoned Heating/Cooling system with multiple thermostats, please refer to our website
at www.Gemtech-thermostats.com for installation notes.
Caution
Do not allow
wires to touch
each other or parts on unit.
Wires must be routed through
the hole in the back plate, below
the terminal block, or they will
hit parts on the cover.

PG 8
The Wire Chart below will help you determine the terminal connections you will use
on your new thermostat. See chart section that applies to your heat/cool system.
OLD THERMOSTAT NEW THERMOSTAT DESCRIPTION
R or RH or 4 or V RH or RC(leave jumper) Power Wire
 
RH or 4 or V RH (remove jumper) Power Heat
RC or R RC (remove jumper) Power cool
W or H W Heat return
Y or M Y Cool return (compressor)
G or F G Fan return
C or X C AC source for thermostat
W2 or H2 W2 2nd stage of heat
Y2 do not connect 2nd stage of cool (n/a)
W2 W2 Heat pump Aux heat
E Do not connect
O (see note below) O Dmpr/Chg-over (pwr in cool)
B (see note below) B Dmpr/Chg-over (pwr in heat)
5 or R RH Power wire (pwr)
4 or W W Turn Valve on
6 or Y or B A Turn Valve off
R RH Power wire (pwr)
Y or B W Turn Valve off
W A Turn Valve on
ONE Power Wire
TWO Power Wires
ZONED MOTOR VALVES
ZONED SOLENOID VALVES
HEAT PUMPS
Note: On a heat pump, if O and B are both present, connect O to O and tape off B.
For wiring support visit our website at www.Gemtech-thermostats.com
Control wires

PG 9
RH
G
Y
W
C
From Furnace
And AC unit
R
or
RC
G
Y
W
C
From Furnace
And AC unit
RH
Go To Page 14 Go To Page 15
Go To Page 13
RH
W
C
From Furnace
G
Go To Page 17
Go To Page 16
W
RH
R
or
From Furnace
Go To Page 12
C
or R
If you do not find the wiring information for your system try our website: www.Gemtech-thermostats.com.
B
G
Y
R
C
From heat pump
with out Aux heat
O
or
B
G
Y
R
C
From heat pump
with Aux heat
O or
W or W2
NOTE: Wires marked with dotted line are optional.

A
G
C
W2 RC
O
B
RH
WY
PG 10
8 Wire Connections cont
When you have finished connecting the wires attach control unit to wall
unit. Hook the top of the body onto the base, swing the body down, and
snap the body onto the base.
9 Check Unit
Follow these procedures to verify you
have correctly installed the unit.
To check HEAT mode:
.
Set the mode switch to HEAT. Set the fan switch AUTO.
.
Using the TEMP UP button raise the set point to 90deg.
.
Allow the system 5 min to respond.
.
Verify that heat is blowing from the system.
.
Set the mode switch to OFF.
To check COOL mode:
.
Set the mode switch to COOL. Wait 5min for compressor delay.
.
Press the TEMP DOWN button to a temp 5o below room temperature.
.
Allow the system 5 min to respond.
.
Verify that cool air is blowing from the system.
.
Set the mode switch to OFF.
To check Fan:
.
Switch mode to OFF during fan test.
.
Switch the FAN switch to the ON position. Verify air is blowing from vents.
.
After test, return fan switch to AUTO, and mode to HEAT or COOL.
Congratulations, you have successfully installed your unit. Please proceed to the OPERATING GUIDE
to initialize the new thermostat. REMEMBER, Mode switch must be in HEAT or COOL to operate.
TEMP UP
button
Mode Switch Fan Switch
TEMP DOWN
button

PG 11
The GT5020 can be used with most 24 volt gas, oil or electric heating and air
conditioning systems, heat pumps or gas millivolt heating systems.It cannot be
used with 120 volt heating systems.
The GT5020 is digital.You can set your desired
Heat and cool temperature set points directly on
the Large LCD display.
You can easily override the set temperatures.
4-minute minimum off time in COOL protects
your air conditioning system from being
damaged.
Two "AA" batteries (not included) are used to retain your time
and temperature programs, and to run the thermostat.
GT5020 Features

PG 12
Go To Page 10
STEP 1 - Connect the R(or RH) wire to the RH terminal on the
thermostat. This connects to the Heater Power.
STEP 2 - Connect the Wwire to the Wterminal on the thermostat. This
connects the heater control line to the thermostat.
Your heater is now connected to the thermostat.
NOTE: Wires marked with
the dotted line are optional.
W
RH
R
or
From Furnace
C
2 WIRE
jumper
wire
FURNACE
HEAT
Thermostat
R W CHEAT
Power

PG 13
STEP 1 - Connect the R(or RH) wire to the RH terminal on the
thermostat. This connects to the Heater Power.
STEP 2 - Connect the Wwire to the Wterminal on the thermostat.
This connects the heater control line to the thermostat.
STEP 3 - Connect the Gwire to the Gterminal on the thermostat.
This connects the Fan to the thermostat.
Your system is now connected to the thermostat.
Go To Page 10
NOTE: Wires marked with
the dotted line are optional.
RH
W
C
From Furnace
G
or R
3 WIRE
FURNACE
jumper
wire
Heat
Power Heat
W G RH C
FAN
Thermostat

PG 14
R
G
Y
W
C
RH
or
From Furnace
and AC unit
STEP 1 - Connect the Y wire
to the Yterminal on the
thermostat. This connects to
the Cooler compressor.
STEP 2 - Connect the RH or Rwire to the RH
terminal on the thermostat.
This connects the Heater/Cooler Power.
STEP 3 - Connect the Wwire to the Wterminal
on the thermostat.
This connects to the heater control line.
STEP 4 - Connect the G wire to the Gterminal on the Thermostat.
This connects to the Fan.
Your HVAC system is now connected to the thermostat.
Go To Page 10
4 WIRE NON-HEAT PUMP
NOTE: Wires marked with
the dotted line are optional.
HVAC SYSTEM
jumper
wire
Heat
Power Heat
WG RH
C
FAN
Y
Cool
Comp
Thermostat

PG 15
From Furnace
and AC unit
G
W
Y
RH
RC
C
STEP 1 - Remove the Jumper wire.
STEP 2 - Connect the Y wire to the
Yterminal on the thermostat. This
connects to the Cooler compressor.
STEP 3 - Connect the RH wire to the
RH terminal on the thermostat. This connects to the
Heater Power.
STEP 4 - Connect the RC wire to the RC terminal
on the thermostat. This connects to the Cooling Power.
STEP 5 - Connect the Wwire to the Wterminal on the thermostat.
This connects to the heater control line.
STEP 6 - Connect the G wire to the Gterminal on the Thermostat.
This connects to the Fan.
Your HVAC system is now connected to the thermostat.
Go To Page 10
5 WIRE NON-HEAT PUMP
NOTE: Wires marked with
the dotted line are optional.
HVAC SYSTEM
Remove
jumper
wire
HEAT
Power
Heat
WG RHRC
C
FAN
Y
Cool
Comp
COOL
Power
Thermostat

PG 16 Go To Page 10
NOTE: Wires marked with
the dotted line are optional.
STEP 1 - Connect the G wire to
the Gterminal on the thermostat.
This connects the Fan.
STEP 2 - notice jumper wire
between Wand Y.
STEP 3 - Connect the Ywire to
the Y terminal on the thermostat.
This connects the Compressor.
STEP 4 - Connect the O or B wire to the O or B
terminal on the thermostat. (If you have both Oand B
wires, use the O and tape off the B.) This connects
the change over valve.
STEP 5 - Connect the R wire to the RC terminal on
the Thermostat. This connects to the 24vac power.
Your HVAC system is now connected to the
thermostat.
HEAT PUMP
w/o Auxiliary Heat
O or B
Single Stage HEAT PUMP
Change
Over
G
O or B
R
C
FAN
Y
Comp
24VAC
Power
jumper
wire
jumper
wire
Thermostat
B
G
Y
R
C
From heat pump
w/o Aux heat
O
or

PG 17
STEP 1 - Connect the G wire to
the Gterminal on the thermostat.
This connects the Fan.
STEP 2 - notice jumper wire
between Wand Y.
STEP 3 - Connect the Ywire to
the Y terminal on the thermostat.
This connects the Compressor.
STEP 4 - Connect the O or B wire to the
O or B terminal on the thermostat. (If you have both
Oand B wires, use the Oand tape off the B).
This connects the change over valve.
STEP 5 - Connect the R wire to the RC terminal on
the Thermostat. This connects to the 24vac power.
STEP 6 - Connect W or W2 to W2 on the thermostat.
This connects the AUX heat.
Your HVAC system is now connected to the thermostat.
Go To Page 10
HEAT PUMP
with Auxiliary Heat
NOTE: Wires marked with
the dotted line are optional.
O or B
(not both)
HEAT PUMP
Change
Over
AUX
Heat
G
O or B
R
C
FAN
Y
Comp
24VAC
Power
jumper
wire
jumper
wire
Thermostat
B
G
Y
R
C
From heat pump
with Aux heat
O
or
W
or
W2

PG 18
Notes -

1-507-013
Customer Support website www.Gemtech-thermostats.com