Honeywell W8835 User Manual
68-0258ES-04
W8835 EnviraZone Panel
FEATURES
• Controls up to three stages heat and two stages
cooling of single-stage, multi-stage, conventional, or
heat pump.
• Controls up to three zones and can be expanded up to
nine zones with two W8703A DIM.
• Uses VisionPRO® IAQ or FocusPRO communicating
thermostats for manual or automatic changeover by
zone.
• Supports dehumidification, humidification and
ventilator controls.
• Purge timer protects equipment between calls for heat
or cool with choice of panel or HVAC equipmentcontrolled fan.
• System and zone damper LEDs indicate system and
damper status.
• Individual zone fan control.
• Supports C7835 Discharge Air Temperature Sensor for
APPLICATION
The W8835 EnviraZone Panel controls single-stage, multistage, conventional or heat pump heat/cool equipment. It
controls three zones, and is expandable up to nine zones with
two additional W8703A Damper Interface Modules (DIM).
For Internet access: http://yourhome.honeywell.com
.
capacity control with adjustable high and low limits
and equipment failure indication.
• Controls duel fuel equipment when used with an
external fossil fuel kit.
PRODUCT DATA
For technical support, call: 1-800-828-8367.
IMPORTANT
Please read these instructions and keep them
in your records.
Contents
Application.........................................................................1
Features ............................................................................2
Specifications ....................................................................2
Ordering Information .........................................................2
Installation .........................................................................4
Startup and Checkout ........................................................8
Operation...........................................................................8
Troubleshooting.................................................................11
W8835 ENVIRAZONE PANEL
SPECIFICATIONS
Input Ratings:
Voltage: 20-30 Vac, 50/60 Hz.
Power: 11 VA nominal, Class II.
Output Ratings (dampers and HVAC equipment):
1.5A run, 200,000 cycles (30 Vac) 3.5A inrush.
1.5A run, 100,000 cycles (30 Vac) 7.5A inrush.
Humidity Ratings:
90 percent RH at 95°F, non-condensing.
Temperature Ratings:
Shipping: -20 to 120°F.
Operating: -40 to 150°F.
LED:
SYSTEM mode LEDs (5) used to communicate equipment
status:
Red Heat: Heat mode.
Green Cool: Cool mode.
Yellow Purge: Purge mode.
Green Fan: Fan mode.
Red Em Heat: Emergency Heat mode.
ZONE LEDs (3) used to communicate damper status:
Green: Dampers are open or opening.
No Color: Dampers are closed or closing.
COM LED (1) used to indicate communication status:
Flashing Green: Panel is transmitting or has received data.
No color: Communications are idle.
Dimensions: 12-3/4 in. W x 10-3/4 in. H x 1-7/8 in. D.
See Fig. 1.
Finish: W8835: Taupe cover, olive-gray base.
Mounting: Mounts with four screws (provided) through holes
in cabinet back (wall anchors provided).
Wiring: Eighteen-gauge wire for all equipment and system
connections.
Wiring Connections:
EnviraCom: Four terminal strips (each with three terminals
labeled 1, 2, 3).
Dampers: Three terminal strips labeled M6 (Closed),
M4 (Open), M1 (Common).
Transformer 1: R (hot), C (Common).
Transformer 2: T1 (hot), T2 (Common).
Equipment: Rc, Rh, W1/E, W2, W3/Aux, Y1, Y2, G, O/B.
Humidifier: HUM, HUM.
Dehumidifier: DHUM, DHUM.
Ventilator: VENT, VENT.
Thermostats:
VisionPRO® IAQ TH9421 or FocusPRO THM5320C Thermo-
stats controls single- or multi-stage conventional and heat
pump equipment.
Accessories:
For required accessories, see Table 2. Optional accessories
include the W8735 Telephone Access Module for
telephone dial-in and dial-out capability, and the W8703
Damper Interface Module to control additional zones.
ORDERING INFORMATION
When purchasing replacement and modernization products from your TRADELINE® wholesaler or distributor, refer to the
TRADELINE® Catalog or price sheets for complete ordering number.
If you have additional questions, need further information, or would like to comment on our products or services, please write or
phone:
1. Your local Honeywell Automation and Control Products Sales Office (check white pages of your phone directory).
2. Honeywell Customer Care
1885 Douglas Drive North
Minneapolis, Minnesota 55422-4386
In Canada—Honeywell Limited/Honeywell Limitée, 35 Dynamic Drive, Toronto, Ontario M1V 4Z9.
International Sales and Service Offices in all principal cities of the world. Manufacturing in Australia, Canada, Finland, France,
Germany, Japan, Mexico, Netherlands, Spain, Taiwan, United Kingdom, U.S.A.
68-0258ES—04 2
W8835 ENVIRAZONE PANEL
Dampers:
See Table 1 for suggested dampers. Dampers are connected to
M1 Common, M4 Open, and M6 Closed (see Fig. 5 through 8
for hookups). Connect no more than five ARD or ZD dampers
to an individual zone.
Connect no more than five ARD or ZD dampers to the panel
when using one 40 VA transformer; connect no more than
ten ARD or ZD dampers when using two 40 VA transformers.
HEAT COOL PURGE FAN EM. HT. COMM ZONE 1 ZONE 2 ZONE 3
10-3/4
(273)
Use SDCR for additional dampers required. If using RRD
dampers, refer to RRD installation instructions for maximum
number of dampers.
Motor Terminal Damper Action
Common/M1 Common
Open/M4 Power Open
Closed/M6 Power Close
TM
12-3/4
(324)
1-7/8
(47)
M20594
Fig. 1. W8835 dimensions in in. (mm).
Table 1. Recommended Dampers
Honeywell Damper Type Round Rectangular
For systems > 2000 cfm. MARD or RRD For recommended dampers, call the Honeywell
Zoning Hotline at 1-800-828-8367.
For systems <= 2000 cfm. ARD or RRD ZD
3 68-0258—04
W8835 ENVIRAZONE PANEL
CAUTION
CAUTION
A
Table 2. Required Accessories (Not Supplied with Panel).
Accessory Description
40 VA transformers
High and low limit sensor
AT140A1042
C7835A1009
Round static pressure regulator damper SPRD7
SPRD8
SPRD9
SPRD10
SPRD12
SPRD14
SPRD16
Rectangular static pressure regulator damper SPRD12x8
SPRD12x10
SPRD12x12
SPRD20x8
SPRD20x10
SPRD20x12
a
Supplied in the Y8835 kits.
INSTALLATION
Mounting
Bypass Rating
(cfm)
a
a
—
—
300
400
600
750
1200
1800
2400
1000
1200
1400
1600
2000
3000
RETURN
AIR
Equipment Damage Hazard.
Do not mount W8835 inside HVAC equipment.
Mount only on wall or on cold air return.
1. Mount the thermostats in each zone of the living space
using the installation instructions provided with each
thermostat.
2. Mount the dampers in the ductwork using the installation
instructions provided with each damper.
3. Mount the W8835 EnviraZone Panel near the HVAC
equipment; locate it on a wall or on the cold-air return.
See Fig. 2.
4. Level the W8835 for appearance only.
W8835
IR CLEANER
E
LE
CTRONI
C
AIR CLEANER
FURNACE
W8835
M31121
Fig. 2. W8835 mounting location.
Wiring
Voltage Hazard.
Can cause electrical shock or equipment damage.
Disconnect power before continuing installation.
Wiring must comply with applicable codes, ordinances,
and regulations.
68-0258—04 4
W8835 ENVIRAZONE PANEL
12 3
12 3
12 3
L
C
RH
RC
W1 /E
W2
W3/AU X
Y1
Y2
G
O/ B
HU M
HU M
DE HUM
DE HUM
VE NT
VE NT
R
C
T1
T2
ZONE 1
M6 M4 M1
ZONE 2
M6 M4 M1
ZONE 3
M6 M4 M1
1 2 3 1 2 3 1 2 3 1 2 3
DA MP ER S E NV IR AC OM BUS
DAM PER
XF RM
EN VI RACO M
XF RM
RE MO VE JU M PER S IF
T1 AND T2 ARE USED
HE AT CO OL ZO NE 1 CO M EM HE AT FA N PU RG EZ ON E 3 ZO NE 2
W8835A
DI P SW IT CH SE TT IN GS
1 SEE TA BL EO NO FF
2 SEE TA BL E1 0
3 EN VI RACO M FU RN NO YE S
4 P URG E TI ME 2 MI N3 .5 MI N
5 P URG E FA NH VA C P ANE L
6 P URG E DAM PE RN O CHG OP EN
7 # CO MP ST AG ES 1 2
8 H E AT FA NH VA C P ANE L
9 H P CHANG EO VE RO B
10 UNU SE D
O
N
1 2 3 4 5 6 7 8 9 10
#1 # 2 CO NV HT ST G
1 1 1
1 0 2
0 1 3
0 0 HP
24 VOLT/40 VA
TR AN SF OR ME R
R
C
L1
L2
R
W1
W2
Y1
Y2
G
C
DO TTE D LI NE S FO R 2ST AG E A PPL IC AT IO NS
SI NG LE TR AN SF OR ME R
H EAT I N G/COOLING SYST EM S
RE QU IR E A JU M PER TO BE
IN ST AL LE D C O NNEC TI NG R H
AND RC (FACTORY INSTALLED) .
12 3
EARD- 6
M31122
POWER-CLOSED/
SPRING-OPEN
ZD DAMPER
POWER-CLOSED/
SPRING-OPEN
ZD DAMPER
POWER-CLOSED/
SPRING-OPEN
ARD DAMPER
C7835A DISCHARGE
AIR SENSOR
LED STATES:
Heat LED Heating Mode
Cool LED Cooling Mode
Purge LED Purge Mode
Fan LED Fan Mode
Em Heat LED Em Heat Mode
COMM LED Communications
ZONE LEDS:
On Damper open or opening
Off Damper closed or closing
MOMENTARY PUSH BUTTONS
Boot Clears Microprocessor
Purge Override Bypass Purge Mode
Discovery Initiates Discovery Mode
Wiring Thermostats
Run wire from the Thermostat 1, 2, 3 terminals to the
corresponding terminals on any one of the EnviraCom bus
terminal sets. More than one thermostat or other
communicating device can be connected to a bus terminal.
See Fig. 3.
Wiring Equipment
CONVENTIONAL EQUIPMENT
Connect the first stage heat to W1/E, second stage heat to W2,
and third stage heat to W3/Aux. Wire first stage cooling to Y1,
and second stage cooling to Y2. See Fig. 3.
If separate HVAC equipment transformers are used for the
heating and cooling systems, such as for an oil furnace, wire
the heating transformer hot wire to Rh and the cooling
transformer hot wire to Rc. Locate the Rh/Rc jumper above the
equipment terminals and remove the jumper to expose the two
pins.
HEAT PUMP EQUIPMENT
Connect the Y1 terminal to the first stage compressor, and the
Y2 terminal to the second stage compressor. W3/Aux is the
auxiliary heat and W1/E is the emergency heat. If emergency
heat and auxiliary heat use the same piece of equipment,
place a jumper from W3/Aux to W1/E and wire it to the resistive
heat equipment. See Fig. 4 and 5. See Fig. 6 and 7 for twostage heat pump equipment.
Fig. 3. Conventional equipment wiring diagram.
5 68-0258—04
W8835 ENVIRAZONE PANEL
For dual fuel equipment using heat pump and fossil fuel,
configure the panel as a heat pump and use a fossil fuel kit. Do
not use the dual fuel functionality of the VisionPRO® IAQ.
Wiring HVAC Equipment
SINGLE TRANSFORMER HEATING/COOLING
SYSTEMS REQUIRE A JUMPER TO BE
INSTALLED CONNECTING R
(FACTORY INSTALLED).
HVAC EQUIPMENT
24 VAC
EQUIPMENT
REVERSING VALVE (COOLING/HEATING)
HEATING TRANSFORMER
COOLING TRANSFORMER
Fig. 4. Wiring single-stage heat pump with separate
Auxiliary and Emergency Heat.
SINGLE TRANSFORMER HEATING/COOLING
SYSTEMS REQUIRE A JUMPER TO BE
INSTALLED CONNECTING R
(FACTORY INSTALLED).
HVAC EQUIPMENT
24 VAC
EQUIPMENT
REVERSING VALVE (COOLING/HEATING)
HEATING TRANSFORMER
COOLING TRANSFORMER
AND R
H
C
AUXILIARY HEAT
COMPRESSOR
FAN RELAY
FIELD INSTALLED JUMPER
1
AND R
H
AUXILIARY HEAT
COMPRESSOR
FAN RELAY
FIELD INSTALLED JUMPER
1
L
C
R
H
R
C
1
W1/E
W
2
W3/AUX
Y
1
Y
2
G
O/B
M31124
C
L
C
R
H
R
C
1
W1/E
W
2
W3/AUX
Y
1
Y
2
G
O/B
M31124
SINGLE TRANSFORMER HEATING/COOLING
SYSTEMS REQUIRE A JUMPER TO BE
INSTALLED CONNECTING R
(FACTORY INSTALLED).
AND R
H
C
HVAC EQUIPMENT
L
C
24 VAC
EQUIPMENT
HEATING TRANSFORMER
COOLING TRANSFORMER
EMERGENCY HEAT RELAY
AUXILIARY HEAT RELAY
FIRST STAGE COMPRESSOR
SECOND STAGE COMPRESSOR
FAN RELAY
REVERSING VALVE (COOLING/HEATING)
R
H
R
C
W
/E
1
W
2
W3/AUX
Y
1
Y
2
G
O/B
M31123
Fig. 6. Wiring two-stage heat pump with separate Auxiliary
Heat.
SINGLE TRANSFORMER HEATING/COOLING
SYSTEMS REQUIRE A JUMPER TO BE
INSTALLED CONNECTING R
(FACTORY INSTALLED).
AND R
H
C
HVAC EQUIPMENT
L
C
24 VAC
EQUIPMENT
HEATING TRANSFORMER
COOLING TRANSFORMER
AUXILIARY HEAT RELAY
FIRST STAGE COMPRESSOR
SECOND STAGE COMPRESSOR
FAN RELAY
REVERSING VALVE (COOLING/HEATING)
FIELD INSTALLED JUMPER
1
1
R
H
R
C
W
/E
1
W
2
W3/AUX
Y
1
Y
2
G
O/B
M31125
Fig. 7. Wiring two-stage heat pump with Auxiliary Heat.
Fig. 5. Wiring single-stage heat pump with Auxiliary Heat.
68-0258—04 6
W8835 ENVIRAZONE PANEL
ARD or ZD Dampers
Wire the ARD or ZD Damper to the panel as shown in Fig. 8.
Multiple dampers can be wired in parallel. Up to five ARD or
ZD dampers can be connected in parallel to one zone. If five to
ten dampers are connected to the panel an additional 40VA
transformer must be connected to the panel.
Fig. 8. Wiring ARD or ZD damper to panel.
RRD
Wire the RRD dampers to the panel as shown in Fig. 9. Two or
more RRD can be wired in tandem as shown in Fig 10. Up to
12 RRD can be wired to one zone. Power the panel with one
40VA transformer if up to 12 dampers are connected to the
panel. Power the panel with two 40VA transformers if up to 26
RRD are connected to the panel.
ZONE
1, 2, 3, ETC.
M6 M4 M1
ZONE
1, 2, 3
M6 M4 M1
M 1
M 6
M 4
M1
M6
M4
M31134
Fig. 10. Wiring two RRD dampers in parallel.
MARD Dampers or Dampers using ML6161
Motor Actuator
Wire the MARD Damper or other damper using the ML6161
Actuator to the panel as shown in Fig. 11. These floating
control actuators are controlled as two-position devices on the
W8835 panel.
The ML6161 motor causes the damper LED to illuminate green
constantly. To restore damper position indication, mount end
switch 201052B onto the ML6161.
M1
M6
M4
M31133
Fig. 9. Wiring RRD damper to panel.
ZONE PANEL
CONNECTIONS
M1 M4
MARD
CW
COM
CCW
M6
M20136A
Fig. 11. Wiring MARD Damper or ML6161 Actuator to
panel.
Transformer
Wire the transformers to the panel (see Fig. 12). One 40 VA, 24
Vac transformer is required to operate the panel and up to five
ARD or ZD dampers. The transformer is connected to
terminals R and C. The auxiliary transformer is required if up to
ten dampers are connected to the panel. It is wired to terminals
T1 and T2. If more than five ARD or ZD dampers are required
for one zone of if more than ten ARD or ZD dampers are
required for the W8835, use the Slave Damper Control Relay
(SDCR). Locate the XFRM jumper shown in Fig. 12. These
jumpers are shipped in the open, disconnected position. This is
the correct position when two transformers are used. When
using one transformer to power the panel, place the jumpers in
the closed position. Do this by removing the jumpers and
installing them so they cover both of their respective pins. If
preferred, one 75 VA transformer may be used on this panel
instead of two 40 VA. If this is done, leave the jumpers in the
open, disconnected position and install a jumper between R
and T1. Wire the transformer to R and C.
7 68-0258—04
W8835 ENVIRAZONE PANEL
CAUTION
R
C
T1
T2
CR
C
R
24 VAC, 40 VA
TRANSFORMER
(REQUIRED IF
MORE THAN
FIVE DAMPERS)
24 VAC, 40 VA
TRANSFORMER
DAMPER
XFRM
PAN EL
XFRM
M31126
REMOVE XFRM JUMPERS
FROM PINS WHEN USING
TWO TRANSFORMERS
Equipment Damage Hazard.
Incorrect transformer wiring can damage panel.
Wire transformers in phase when one transformer
is wired to R and C and the auxiliary transformer
is wired to T1 and T2.
4. On the W8835 Panel, set the DIP switches.
a. Set DIP switches 1, 2, and 7 to assign the
appropriate number of heating and cooling stages.
See Tables 5 and 6.
b. Configure other DIP switches, as necessary to fit the
application. See Table 6.
5. On each thermostat, enter the Installer Setup procedures
using the VisionPRO® IAQ Installation Instructions and
assign each thermostat a zone number to correspond
with its zone damper.
6. Run Discovery by pressing the Discovery button on the
zone control panel.
7. On each thermostat, enter the Installer Setup
procedures using the Installation Instructions and configure other pertinent Installer Setup options. Program the
thermostat schedule if the default settings are not
desired.
8. Run Discovery by pressing the Discovery button on the
panel.
9. Set Zone one thermostat to heat and raise the setpoint to
call for heat.
a. Verify that the heat LED is red.
NOTE: The furnace heat may not come on immedi-
ately. Allow at least 5 minutes for heat to begin
after the thermostat calls for heat.
Wiring C7835 Discharge Air
Temperature Sensor
Connect wire terminals 1, 2, and 3 to the corresponding
terminals on either the W8835 EnviraZone panel or any other
EnviraCom device such as a thermostat. Refer to C7835
Installation Instructions for configuration. Multiple devices can
be wired in parallel to the each of the 1, 2, 3 terminals.
STARTUP AND CHECKOUT
1. Verify that the equipment, thermostats, transformer, and
Discharge Temperature Sensor are wired correctly. If
one transformer is powering the panel, install the XFRM
jumper. If two transformers are powering the panel, leave
the XFRM jumper in the open position.
2. Power up the W8835. Verify that all LEDs except COM
illuminate for five seconds.The board should then enter
the Purge mode with all dampers open. The damper
LEDs are green to indicate the dampers are open.
The COM LED begins to blink.
3. Press the Purge Override button to terminate the Purge
mode.
68-0258—04 8
Fig. 12. Wiring transformer(s) to panel.
b. Verify that Zone one LED remains green.
c. Verify that all other zone LEDs are not illuminated.
d. Change thermostat mode from Heat to Off.
10. Set Zone two thermostat to heat and raise the setpoint to
call for heat.
a. Verify that the heat LED is red.
b. Verify that Zone two LED remains green.
c. Verify that all other zone LEDs are not illuminated.
d. Change thermostat mode from Heat to Off.
11. Alternatively, set a thermostat to Cool, lower the
setpoint to call for cooling, wait five minutes, and verify
correct operation.
OPERATION
Sequence of Operation
When there is no call for heat, cool or fan, the board is in the
idle mode, indicated with no system LEDs illuminated, see
Table 3. Damper LEDs are green to indicate open. On a call for
heat, cool, or fan, the calling zone damper stays open and the
damper LED remains illuminated; the other zone dampers
close and corresponding damper LEDs do not illuminate.
The W8835 panel energizes the HVAC equipment and
conditioned air is delivered to the calling zone. The heat LED
(red), cool LED (green), or fan LED (green) illuminates to
indicate equipment operation.
The fan LED illuminates only on a call for fan; it does not
illuminate during a call for heat or cool. When the heat/cool call
is satisfied, the system enters the Purge mode, indicated by
the Purge LED (yellow). Damper positions either remain in the
same positions as at the end of the call for heat or cool
(default) or open, depending on the position of DIP switch 6.
After purge, all dampers return to the Open position.
COM LED Operation
The green COM LED flickers as the W8835 communicates
with the other EnviraCom devices:
LED blinks rapidly—indicates device is currently
transmitting information on the communications bus.
W8835 ENVIRAZONE PANEL
LED blinks once—indicates device received and
acknowledged a message.
LED on constantly— indicates panel failure. Replace panel.
LED off constantly—indicates a wiring problem.
Table 3. LED Indicators
LED Color Illuminated Not Illuminated
Heat Red Heat call. No heat calls.
Cool Green Cool call. No cool calls.
Purge Amber Purge mode. Not in Purge mode.
Fan Green Fan only call. No fan only call.
Em Heat Red Emergency Heat mode. Not in Emergency Heat mode.
Zone 1, 2, 3 Green Damper is open or opening. Damper is closed or closing.
b
An LED change precedes the corresponding relay change by as much as six seconds.
Purge Mode
At the end of every call for heat or cool, the panel enters a
Purge mode. DIP 4 configures the panel to purge for two
(default) or three and one-half minutes. DIP switch 5
configures the panel or the HVAC equipment to operate the fan
during purge.
The Purge LED lights to signal that the system is in the Purge
mode. Pressing the purge override button overrides the Purge
mode.
Individual Zone Fan Control
When all zones are satisfied, the fan switch of each thermostat
controls the fan operation for that zone. When the fan setting is
“ On”, the fan is energized, the fan LED illuminates and the
dampers close to zones where the fan setting is “Auto”. If there
is a call for heat or cool during this time, the fan mode ceases,
and the heat or cool call is honored. When the zone calling is
satisfied, and Purge mode has ended, the fan call resumes.
b
Single and Multi-Stage Conventional
Unless there is a new call for heat or cool during the Purge
mode, all dampers are moved to the Open position at the end
of purge. DIP switch 6 is used if it desired to open all dampers
during the Purge mode.
Table 4. Purge Configuration
DIP Switch
Number
4 Off (Down) 3.5 minutes purge
4 On (Up) 2 minutes purge
Table 5. Fan Control Configuration
DIP Switch
Number
5 Off (Down) Panel control of fan
5 On (Up) HVAC control of fan
Status Purge
Status Fan Control
in Purge
in Purge
Heat Operation
The panel can control up to three stages of heating and two
stages of cooling based on thermostat demand. Set DIP
switches 1 and 2 for 1, 2 or 3 stages of heat. Set DIP switch 7
for one or two stages of cooling.
Table 7. Conventional Equipment Configuration
1 Stage Cooling
Equipment Type DIP 1 DIP 2
1 Stage Conventional On (Up) On (Up)
2 Stage Conventional On (Up) Off (Down)
3 Stage Conventional Off (Down) On (Up)
2 Stage Cooling
Cooling Stage DIP7
1 Stage On (Up)
2 Stage Off (Down)
Table 6. Purge Damper Configuration
DIP Switch
Number
6 On (Up) Last zone(s) calling
6 Off (Down) Open all dampers
Status Purge Damper
open during Purge
during Purge
9 68-0258—04
W8835 ENVIRAZONE PANEL
Heat Pump Operation
The panel can control one or two compressor stages plus
auxiliary heat. Set DIP switch 1 and 2 to Off; set DIP switch 7
to On for a single-stage compressor and to Off for a two-stage
compressor.
Table 8. Heat Pump Equipment Configuration
Equipment Type DIP 1 DIP 2
Heat Pump Off (Down) Off (Down
Compressor Stages DIP 7
1 Stage On (Up)
2 Stage Off (Down
Heat Pump Changeover DIP 9
O (Cool) On (Up)
B (Heat) Off (Down
Wire the reversing valve to the O/B equipment terminal. DIP
switch 9 configures this terminal to operate as an O (cool) or
B (heat) changeover terminal.
Hydronic Heat Operation
The W8835 is a forced air panel. However, it can be wired to
control hydronic valves as shown in figure 13. To control
valves or circulators on a hydronic panel, see figure 14.
Thermostat Operation
Dual Fuel Equipment
The W8835 can operate Dual fuel equipment when used with
an external fossil fuel kit. Locate the thermostat on the fossil
fuel kit instructions and wire the W8835 equipment terminals
there.
Emergency Heat Control
Emergency heat is defined as using an auxiliary heat source
without using the heat pump. The W8835 energizes the E
terminal on a call for emergency heat. The thermostat system
switch is set to Em Heat to engage this function. When active,
any zone calling for heat uses Emergency Heat, not the
compressor.
The panel energizes W3 as auxiliary heat with the Y1 and Y2
for compressor control in when not in emergency heat.
Manual and Automatic Changeover Operation
Each of the thermostats can be set for manual or automatic
changeover. If one or more thermostats call for cooling while
one or more thermostats call for heating, the panel attempts to
satisfy the greatest demand first.
Then, based on the relative demand for heating and cooling,
the panel intelligently switches between heating and cooling.
The system attempts to satisfy both the heating and cooling
demands, and does not lock out one demand in favor of the
other.
Discovery
Discovery is an automatic system configuration program where
the panel configures itself to operate with controls connected to
the EnviraCom bus. The panel enters Discovery when the
Discovery button on the panel is pressed.
Rebooting Microprocessor
To reset the microprocessor, press and release the Boot
button. The system reboots and enters the Purge mode.
EnviraCom Furnace
For furnaces with EnviraCom communications built in,
configure the panel as shown below. In this case, no
conventional equipment wiring is necessary because the
W8835 uses the 3-wire EnviraCom bus to control the HVAC
equipment. In these installations, the panel is powered from
the HVAC equipment via the 1, 2, 3 wires. Because of this, the
transformer R and C terminals on the W8835 are not used.
Instead, leave the XFMR jumpers in their default disconnected
position and wire the transformer to T1 and T2.
Table 9. Furnace Type Configuration
Type of Equipment DIP 3
Conventional On (Up)
EnviraCom Off (Down)
Humidity, De-humidity and
Ventilation Control
The panel can control humidity, de-humidity, and ventilation by
receiving messages from the VisionPRO® IAQ thermostat.
The thermostat designated as zone 1 will have control of these
functions. Configure this thermostat as found in the installation
instructions for the thermostat.
The humidity, de-humidity, and ventilation terminals are all drycontact terminals; the relay contacts close when active. So
devices that need dry contact control like a ventilator can be
wired directly to the VENT terminals, or a steam humidifier can
be wired directly to the HUM terminals. Devices that need to be
powered like a ventilation damper or some models of
evaporative humidifiers are wired using the VENT or HUM
terminals wired through the R terminal as shown in Fig. 3.
If using a Honeywell TrueSteam humidifier, configure the zone
one VisionPRO IAQ thermostat installer setup #374 to "3", and
wire the TrueSteam GF terminal to the HVAC fan terminal, and
wire the TrueSteam GT terminal to the G on the W8835.
NOTE: When controlling a steam humidifier, set all thermo-
stats to HEAT. Do not set thermostats to AUTO. This
prevents the panel from humidifying on zone 1, when
another zone is calling for cooling. Alternatively, set
zone 1 thermostat Installer Setup 374 to “2” to allow
humidification only during calls for heat.
68-0258—04 10
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