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8

Step 3: Testing the Thermostat

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

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

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

COOL position.  The 

will be displayed.

2. Press the 

button until the temperature

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

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

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.

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

position. The air conditioning system should
turn off.

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

position. The  will be displayed.

5. Press the 

button until the temperature

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.

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

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 posi-

tion. The blower fan should turn off.

heat off cool

heat off cool

heat off cool

!

heat off cool

auto  on

auto  on

110-1087B.qxd  3/4/05  4:00 PM  Page 8

Summary of Contents for 8401

Page 1: ...ctric 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...

Page 2: ...rcury 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 80...

Page 3: ...ng wiring does not directly match the labels 4 Remove existing thermostat base from wall 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 ...

Page 4: ...an 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 matchin...

Page 5: ...COOL 4 WIRE SINGLE TRANSFORMER Fan Control Hot Heating Control Transformer 24 VAC 120 VAC HEAT ONLY 2 WIRE SINGLE TRANSFORMER W1 Y1 G T H E R M O S T A T O B C R Hot Heating Control Fan Control Transformer 24 VAC 120 VAC HEAT ONLY SINGLE TRANSFORMER 3 WIRE W1 Y1 G T H E R M O S T A T O B C R Wiring Diagrams ...

Page 6: ...E R M O S T A T NOTE Make sure the HP switch is in the HP position When switched to HP mode W1 is connected internally to Y1 Reversing Valve Fan Relay C R Hot Transformer 24 VAC 120 VAC HEAT PUMP WITH HEAT ACTIVE REVERSING VALVE W1 T H E R M O S T A T NOTE Make sure the HP switch is in the HP position When switched to HP mode W1 is connected internally to Y1 Compressor Contactor Y1 G O B Reversing...

Page 7: ...nection C 24VAC common connection Yes For input of 24VAC common side of transformer W1 Heat connection Yes Energizes on a call for heating Y1 Compressor Connection Yes Energizes on a call for cooling B Heat active reversing valve No Energizes when in the HEAT mode O Cool active reversing valve No Energizes when in the COOL mode G Indoor fan connection Yes Energizes with Y1 W1 terminals or with FAN...

Page 8: ...LAY IS REQUIRED TO OVERRIDE THE 5 MINUTE DELAY FOR INSTALLATION PRESS THE RESET BUTTON 3 Put the HEAT OFF COOL switch into the OFF position The air conditioning system should turn off 4 Put the HEAT OFF COOL switch into the HEAT position The will be displayed 5 Press the button until the temperature setting is at least 3 degrees above room temperature The heating system should turn on The fan may ...

Page 9: ...renheit 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 s...

Page 10: ... 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 temper ature 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 pres...

Page 11: ...urs service a 24 hour automated helpline is available Thermostat turns system on and off too frequently Increase temperature differential see Changing the Temperature Differential section System fan does not operate properly Move Electric Gas switch to either gas or electric to match system see Installation section Thermostat does not display proper room temperature Check F C Fahrenheit Celsius se...

Page 12: ...air 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...

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