Robertshaw 8401 User Manual

DIGITAL
NON-PROGRAMMABLE
THERMOSTAT

8

401

ELECTRIC

E

GAS

G

OIL

O

®

NeW

1 Heat / 1 Cool

User's Manual

Quick Start
Installation

HEAT PUMP

H

110-1087B

Application

The Robertshaw 8401 is a single-stage thermostat designed to control
24 VAC gas or electric heating and cooling systems or single-stage heat
pump. The 8401 requires the use of a common wire.

Features

• Large backlit display

• Adjustable temperature differential: 1°F to 3.0°F (0.5°C to 1.5°C)

• Compressor short cycle protection

• Accuracy within ±1°

• Zone system compatible as a master thermostat

• Permanent memory retention

• Fahrenheit/Celsius display option

• Adjustable from 45°F to 90°F (7°C - 32°C)

• Quick wire terminal block

1

!

WARNING:

• Always turn off power at main fuse or circuit breaker panel before
installing, removing, cleaning, or servicing thermostat.

• Read all the information in this manual before installing this thermostat.

• DO NOT CONNECT TO 120 VAC. This is a 24 VAC low-voltage
thermostat. Do not install on voltages higher than 30 VAC.

• All wiring must conform to local and national building and electrical
codes and ordinances.

• Do not short (jumper) across terminals on the gas valve or at the
system control to test installation. This will damage the thermostat
and void the warranty.

• Do not connect ground to any terminal in this unit.

Recycling Thermostat

If this thermostat REPLACES a thermostat that contains mercury,
DO NOT discard the old thermostat in the regular trash. Mercury
is harmful to humans and the environment. For this reason, do
not open, break, or crush the mercury cell. If mercury leaks from
a damaged cell, DO NOT touch or handle mercury with bare
hands. Use protective, non-absorbent gloves to place mercury
into a sealable container. Fill the container with sand or another
absorbent material and seal the container completely.

Return the mercury or mercury products, in a sealed container, to
Invensys Controls Americas or a local recycling center for proper
disposal. If you have any questions, call Robertshaw technical
support at 1-800-445-8299.

Invensys Controls Americas
28C Leigh Fisher Blvd.
El Paso, TX 79906
Attn: Mercury Recycling Center

Step 1: Replacing Existing Thermostat

Wiring Table

Old Terminal New Label Description

M, W, Rh, Rc R 24VAC, hot side
R5, V or 5

C, X or B C 24VAC transformer, common side

Y or Y6 Y1 Cooling control

H,W, or 4 W1 Heating control

F or G G Fan control relay

O O Cool active reversing valve

B B Heat active reversing valve

NOTE: THIS THERMOSTAT REQUIRES A 24 VAC COMMON WIRE FOR PROPER OPERATION.

NOTE: ON SOME OLDER MODELS, THE C TERMINAL CAN BE EITHER THE COOLING CONTROL OR
THE COMMON SIDE OF THE TRANSFORMER. CHECK FURNACE WIRING DIAGRAM TO VERIFY C
TERMINAL. IF IT IS THE COMMON SIDE OF THE TRANSFORMER, CONNECT TO THE C TERMINAL.

2

heat off cool

auto on

°

!

WARNING:

In heat pump applications, do not connect anything to the W1
terminal. When switched to HP mode, W1 is connected internally
to Y1 on the thermostat.

1. Turn off power to heating and cooling system.

2. Remove cover from old thermostat to expose wires (Figure 1).

3. Disconnect wires one at a time from existing terminals. Use enclosed
labels to mark existing wires. Refer to cross references in the Wiring Table
if existing wiring does not directly match the labels.

4. Remove existing thermostat base from wall.

Figure 1

Step 2: Installing Model 8401 Thermostat

NOTE: FOR NEW INSTALLATIONS, MOUNT THERMOSTAT ON

INSIDE WALL, FIVE FEET ABOVE THE FLOOR. DO NOT
INSTALL BEHIND A DOOR, IN A CORNER, NEAR AIR
VENTS, IN DIRECT SUNLIGHT, OR NEAR ANY HEAT OR
STEAM GENERATING FIXTURES. INSTALLATION AT THESE
LOCATIONS WILL AFFECT THERMOSTAT OPERATION.

1. Turn power off to the heating and cooling systems.

2. Place HEAT-OFF-COOL in OFF position (Figure 2).

3. Place AUTO-ON switch into AUTO position (Figure 2).

heat off cool

auto on

°

F

Figure 2

3

4. Remove the cover using a coin or screwdriver (Figure 3). Set aside.

auto on

at off cool

he

°

F

N

O

M

set

vac

p

clock

tem

hold

hold

run/set

prog

Figure 3

5. Place thermostat against the wall at desired location. Make sure
wires will feed through opening (Figure 4) on base of thermostat.

Mounting Holes

°

F

C

R

GOB Y1W1

ELEC GAS

NON_HP HP

Figure 4

6. Mark placement of mounting holes (Figure 4). Set base aside.

7. If mounting on drywall, tap plastic anchors into wall.
NOTE: Enclosed plastic anchors do not require a drilled hole
for drywall.

8. If mounting on a surface other than drywall, drill the marked holes
using a 3/16" (5mm) drill bit.

9. Align base with plastic anchors and feed wires through opening.

10. Secure base to wall with supplied screws. NOTE: The thermostat
will mount horizontally on a single gang junction box.

11. Strip end of wires 5/16” (8mm) if needed.

12. Terminal screws are already loose and ready for wire insertion.
Insert wires into terminal strip (Figure 4) matching the label to the
corresponding terminal (see Wiring Diagrams). Tighten screws.

4

♦ Wiring Diagrams

HEAT/COOL

4-WIRE

SINGLE TRANSFORMER

R

W1

Y1

T
H

C

E

R
M
O

S

T

G

A

T

O

B

Transformer

Hot

120 VAC

24 VAC

Heating
Control

Cooling
Control

Fan

Control

SINGLE TRANSFORMER

HEAT ONLY

3-WIRE

Transformer

Hot

120 VAC

HEAT ONLY

2-WIRE

SINGLE TRANSFORMER

R

Transformer

Hot

120 VAC

24 VAC

Heating

Control

W1

T

C

H

E

R

Y1

M
O

G

S
T

O

A

T

B

24 VAC

Heating
Control

Fan

Control

W1

Y1

R

T

C

H
E

R
M
O

S

T

G

A

T

O

B

5

♦ Wiring Diagrams (continued)

COOL ONLY

3-WIRE

SINGLE TRANSFORMER

Transformer

Hot

120 VAC

24 VAC

Cooling
Control

Control

HEAT PUMP WITH

HEAT ACTIVE

REVERSING VALVE

R

T

C

H

E

W1

R

Y1

M
O

Fan

S

G

T

O

A

T

B

HEAT PUMP WITH

COOL ACTIVE

REVERSING VALVE

R

Transformer

Hot

120 VAC

24 VAC

Compressor

Contactor

Fan

Relay

Reversing

Valve

NOTE: Make sure the HP switch is in the HP
position. When switched to HP mode,
W1 is connected internally to Y1.

T

C

H
E

W1

R

M

Y1

O

G

S
T

A

O

T

B

Transformer

Hot

120 VAC

24 VAC

Compressor

Contactor

Fan

Relay

Reversing

Valv e

NOTE: Make sure the HP switch is in the HP
position. When switched to HP mode,
W1 is connected internally to Y1.

R

T

C

H
E

W1

R
M

Y1

O

G

S

T

A

O

T

B

6

TERMINAL LEGEND - 8401

TERM EQUIPMENT TO CONNECT REQ? TERMINAL FUNCTION

R 24VAC hot connection Yes For input of 24VAC hot

C 24VAC common connection Yes For input of 24VAC

W1 Heat connection Yes* Energizes on a call for

Y1 Compressor Connection Yes* Energizes on a call for

B Heat active reversing valve** No Energizes when in the

O Cool active reversing valve** No Energizes when in the

G Indoor fan connection Yes Energizes with Y1 & W1

* This thermostat can be used as a heat only or cool only thermostat. Therefore it is not always

necessary to use both Y and W.

**The O and B terminals are accessory terminals that typically are used for heat pump applications.

connection

common side of
transformer

heating

cooling

HEAT mode

COOL mode

terminals or with FAN
option switched to the
ON position

°

F

C

R

GOB Y1W1

ELEC GAS

NON_HP HP

HP OPTION SWITCH

ELECTRIC/GAS SWITCH

Heat pump switch.

Selects fan control.

Figure 5

13. Make sure wire connections are secure.

14. Push excess wire back through opening.

15. Set the Electric/Gas switch to either GAS for a gas/oil heating
system or ELEC for an electric heating system (Figure 5).

16. Set the HP option switch to either the HP for heat pump or
NON_HP for furnace applications (Figure 5).

17. Replace thermostat cover by snapping into place.

7

Step 3: Testing the Thermostat

heat off cool

heat off cool

heat off cool

heat off cool

auto on

auto on

!

WARNING: DO NOT SHORT (JUMPER) ACROSS TERMINALS OF GAS

VALVE OR SYSTEM CONTROL TO TEST OPERATION. THIS WILL
DAMAGE THE THERMOSTAT AND VOID YOUR WARRANTY.

CAUTION: DO NOT SWITCH SYSTEM TO COOL OR LEAVE IN COOL MODE

1. Place the HEAT-OFF-COOL switch into the

2. Press the button until the temperature

NOTE: ONCE THE THERMOSTAT TURNS OFF WHEN IN THE COOL MODE,

3. Put the HEAT-OFF-COOL switch into the OFF

4. Put the HEAT-OFF-COOL switch into the HEAT

5. Press the button until the temperature

NOTE: If HP is selected, the heat will not come on until the 5 minute

IF THE TEMPERATURE IS BELOW 50°F (10°C). THIS CAN
DAMAGE THE AIR CONDITIONING SYSTEM AND CAUSE PER­SONAL INJURY.

COOL position. The will be displayed.

setting is at least 3 degrees below the room
temperature. The air conditioning system
should turn on within a few seconds.

A BUILT IN 5-MINUTE DELAY PREVENTS THE SYSTEM FROM
TURNING ON AGAIN. THIS PROTECTS THE COMPRESSOR. NO
ADDITIONAL TIME DELAY RELAY IS REQUIRED. TO OVERRIDE THE
5-MINUTE DELAY FOR INSTALLATION, PRESS THE RESET BUTTON.

position. The air conditioning system should
turn off.

position. The will be displayed.

setting is at least 3 degrees above room
temperature. The heating system should turn on. The fan may
not turn on immediately, depending on the fan delay built into
the furnace.

short cycle protection has expired.

6. Put the HEAT-OFF-COOL switch into the OFF
position. The heating system should turn off.
The fan may continue to run for a short
period of time.

7. Put the AUTO-ON switch into the ON
position. The blower fan should turn on.
The display will show a .

8. Put the AUTO-ON switch into the AUTO posi­tion. The blower fan should turn off.

8

Step 4: Customizing the Thermostat

♦ Settings

System

Cool: The thermostat controls the cooling.
Off: The heating and cooling systems are off.
Heat: The thermostat controls the heat.

Fan

Auto: Equipment controls the fan.
On: The fan operates continuously.

♦ Temperature Differential

The temperature differential is factory set at 1.0°F (.5°C). This means that
whenever the room temperature changes by one degree Fahrenheit
from the temperature setting, the system will turn on. If the system turns
on too often, increase the temperature differential.

♦ Changing Fahrenheit (°F) to Celsius (°C),

the Temperature Differential, and
the Filter Monitor

1. The thermostat is preset to display the

temperature in degrees Fahrenheit (US
models) or degrees Celsius (Canadian
models). The temperature display can be
changed. Press and hold both the

and buttons for three seconds. The display will flash either an F

or C. Release buttons. Press the or button to switch the display.

2. Wait five seconds or press and the display will switch to the

differential setting.

3. The display will read diFF. The tempera-

ture differential is factory set at 1.0°F
(0.5°C). Press the or button to adjust
the differential up or down.

4. Wait five seconds or press and the

display will switch to the
filter monitor setting.

5. CHECK FILTER and the length of hours for

the filter monitor will be displayed.

6. Use the or to adjust the filter timer

from 0 (OFF) to 9900 hours. NOTE: The
filter timer is based on equipment run
time. Select the length of time based on
the recommended service interval for
your filter.

7. Press the to return to normal operation.

9

♦ Check Filter Reset

Once the filter timer has expired,
CHECK FILTER will turn on and stay
on. To clear the message and reset
the timer:

1. Press the and buttons and hold
for 3 seconds. CLr will appear in the
time display.

2. Press any key to clear the message.
The display will transition to the
temperature scale display as
described in the previous section.

3. No further input is needed. Within a few seconds, the display will
return to the normal operating mode.

♦ Backlit Display

This thermostat is equipped with a backlight to make night time temper­ature adjustments quick and easy. Press the button to activate the
backlight. The backlight will turn off after about 10 seconds of inactivity.

♦ Reset

To reset the thermostat press the RESET button located above the upper
left corner of the display.

GOB Y1W1

C

R

ELEC GAS

°

F

NON_HP HP

RESET switch

10

Step 5: Troubleshooting

Symptom Remedy

Thermostat does not turn on system.

Thermostat turns system on and
off too frequently.

System fan does not operate
properly.

Thermostat does not display
proper room temperature.

Check wiring (see Installation
section).

Increase temperature differential
(see Changing the Temperature
Differential section).

Move Electric/Gas switch to
either gas or electric, to match
system (see Installation section).

Check F/C (Fahrenheit/Celsius)
setting. See Changing Fahrenheit

(F) to Celsius (C).

If problems with thermostat cannot be resolved, call:

Technical Support: [phone]

Monday-Friday 7:30 AM - 5:30 PM CST

For after hours service, a 24-hour

automated helpline is available.

11

Two Year Limited Warranty

Invensys Controls Americas warrants to the original contractor

installer, or to the original consumer user, each new Robertshaw
thermostat to be free from defects in materials and workmanship under
normal use and service for a period of two (2) years from date of
purchase. This warranty and our liability does not apply to batteries or
merchandise that has been damaged by misuse, neglect, mishandling,
alterations, improper installation, or use in a way other than in
accordance with Invensys Controls Americas recommendations
and instructions.

Invensys Controls Americas agrees to repair or replace at its option any
thermostat under warranty provided it is returned within the warranty
period, postage prepaid, with proof of the date of purchase. Cost of
thermostat removal or reinstallation is not the responsibility of Invensys
Controls Americas.

Repair or replacement as provided under this warranty is the exclusive
remedy of the consumer. Invensys Controls Americas shall not be liable
for any incidental or consequential damages for breach of any express
or implied warranty on this product, or under any other theory of liability.
Except to the extent prohibited by applicable law, any implied warranty of
merchantability or fitness for a particular purpose on this product is
limited to the duration of this warranty.

Some states do not allow the exclusion or limitation of incidental or
consequential damages, or allow limitations on how long an implied
warranty lasts, so the above limitations or exclusions 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.

For warranty returns, send thermostat, shipping prepaid to:

Invensys Controls Americas

Warranty Claims Department

515 S. Promenade

Corona, CA 92879-1736

Controls Americas

191 E. North Avenue
Carol Stream, Illinois 60188
United States of America

©2005 Invensys Controls Americas 110-1087B

12