Honeywell International Inc. W8735ER01 Manuale Utente

66-1202—01

4

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.)

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.

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.

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