W8735ER WIRELESS OUTDOOR RESET MODULE
66-1202—01
4
OPERATION
General
The W8735ER Wireless Outdoor Reset Module is a device
which when connected to an AquaReset enabled Electronic
Aquastat, Integrated Boiler Control (IBC) or SOLA control via
the EnviraCOM™ communication bus, enhances the available
control features to include Outdoor Temperature Reset, a
stepped Boost function as well as Warm Weather Shutdown
to provide increased boiler efficiency while servicing the heat
demand. Set-up of the Outdoor Setback curve as well as the
Boost function is done using the 3-digit/3-button display on the
L7224/L7248 Aquastat (see L7224 Installation Instructions
Form Number 69-1720 and/or Form Number 68-0281 for
more information). For the IBC setup see
Form Number 66-
1203 Installation Instructions for more information. For SOLA,
set-up of the reset curve is done using the S7910 or S7999
display (See Form Numbers 65-0315, 66-1175, and 68-0295
for more information.)
Adjusting Aquastat and IBC Settings
To discourage unauthorized/unintentional changing of
Aquastat and IBC settings, a procedure to enter the
ADJUSTMENT mode is required. To enter the ADJUSTMENT
mode, press the UP, DOWN, and I buttons (See Fig. 4)
simultaneously for three seconds. Next, press the
I
button until
the feature requiring adjustment is displayed then use the
arrow up/down buttons to set the parameter value (See Table
4). After 60 seconds without any button inputs, the controller
will automatically return to the normal display mode.
Fig. 4. Location of L7224/L7248 and S936X 3-digit display and buttons.
Outdoor Reset
The Outdoor Reset feature adjusts the target boiler
temperature to a point below its local high limit setting and
above the boiler's condensation temperature by using the
EnviraCOM communication bus to directly adjust the Aquastat
set-point. Should a call for Domestic Hot Water be detected,
the boiler temperature is commanded to return to the High
Limit setting, ensuring a hot water supply is available. When
the Domestic Hot Water demand is met, the Outdoor Reset
feature is once again enabled. See Table 1 and Fig. 5.
Application and Settings Pointers
The energy savings concept behind Outdoor Reset is to
minimize the energy in the boiler that is lost during the off
cycle. This is accomplished by maintaining the boiler
temperature as low as possible and/or running the boiler for
longer periods of time. Although considerable energy savings
exists, the boiler is only one part of the system that includes
thermostats, other controls, and radiation. To maximize
savings while avoiding call-backs due to uncomfortable
homeowners, care must be taken when adjusting the control
parameters. Listed below are operation and adjustment
pointers. See Fig. 5.
Low Boiler Temperature:
This is the minimum temperature
at which the boiler is designed to operate. Setting this too low
during warmer periods may result in condensation in the boiler
and reduce boiler life. Typically this setting is 130 °F (54 °C)
for gas boilers and 140 °F (60 °C) for oil boilers and is
adjusted to be maintained at the high outdoor temperature
setting. Some new cast iron boilers are designed to operate at
lower temperatures. Consult the manufactures' specifications.
Low Outdoor Temperature:
As the outdoor temperature
decreases, the boiler temperature must increase to provide
more heat to the space. The Low Outdoor Temperature
C1
B1
ZC
L2
LINE
C2
ZR
L1
B2
T
T 3
2
1
THREE-DIGIT
DISPLAY
BUTTONS
M33913
GND
BUTTONS
THREE-DIGIT
DISPLAY