Ventilation - Honeywell TH8321 Product Data

2. Select Auto.
Dehumidification
Off
Fig. 156.
 
3. Touch or to select humidity level.
4. Touch Done to save your settings. Touch Cancel to
ignore changes.
If your air conditioner is used to control humidity, the
thermostat may use the following methods to maintain
humidity:
• Cool from 1° to 5° F lower than your temperature
setting.
• Run cooling for the minimum "on" time to reduce
humidity.
• Run cooling and heating at the same time to reduce
humidity without lowering the temperature.
NOTE: If humidification and dehumidification are setup
to operate in the same system mode (Heat, Cool,
Off), the thermostat will automatically enforce a
15% deadband between the humidification and
dehumidification settings. The thermostat will
automatically switch between humidification and
dehumidification to maintain the desired
humidity.

Ventilation

The thermostat can be set for the following ventilation
types: (ISU 1000)
• ERV/HRV
• Passive (Fan Only)
• Fresh Air Damper
Ventilation Control Methods (ISU 1005)
Ventilation can be setup to meet either ASHRAE or Percent
On Time settings. To meet these settings, the thermostat
will ventilate during calls for heat, cool, and fan. If the
required ventilation has not been achieved for ASHRAE or
Percent On Time, the thermostat will force the ventilation
equipment on.
• ASHRAE
The thermostat operates ventilation equipment to meet
the ASHRAE 62.2 ventilation standard based on CFM,
number of bedrooms, and square footage of the house.
ASHRAE 62.2 can only be met if the ventilation
equipment is running. If the ventilation equipment is off
for any reason (outdoor ventilation lockouts, set up to
Auto
MCR34131
VISIONPRO® 8000 SMART THERMOSTAT
turn Off during Sleep period, turned off by user, etc.),
ASHRAE 62.2 is not met during those times. See ISU
1012 to select a Ventilation Priority.
• Percent On Time
The thermostat operates ventilation equipment based
on a percentage entered in the installer setup (ISU
1012). For example if Percent On Time is set to 50%, the
ventilation equipment will run at random times during a
1 hour period until it reaches a 50% run time
(approximately 30 minutes). Default setting is 30%.
Range is 10% to 100% in 10% increments.
Ventilation Fan Control (ISU 1006)
• Tstat Controls Fan
The thermostat turns on the ventilator and the fan when
ventilation is needed.
• Equip Controls Fan
The thermostat turns on the ventilator when ventilation
is needed. The fan is controlled by the equipment.
Ventilation Priority (ISU 1012)
• Lockouts are Priority
The thermostat places a priority on lockouts versus the
ASHRAE 62.2 ventilation standard. The thermostat will
not run ventilation during the following lockout
conditions (if configured) unless you manually call for
ventilation:
— Lockout Ventilation during Outdoor Conditions (ISU
1013)
— Lockout Ventilation on Humidification or Dehumid-
ification Calls (ISU 1014)
— Lockout Ventilation during "Sleep" (Residential) or
"Unoccupied" (Commercial) program periods. Note:
This option is set by the user on the Ventilation
screen in the Menu.
• ASHRAE is Priority
ASHRAE requires additional ventilation following a long
off cycle. The thermostat meets the ASHRAE 62.2
ventilation standard by running additional ventilation
when outdoor conditions are favorable. If ASHRAE
cannot be met when outdoor conditions are favorable,
the thermostat will override the outdoor lockouts and
run ventilation. When using this option, it is
recommended to increase the rate (CFM) of the
ventilation equipment to meet the ASHRAE 62.2
ventilation standard in a shorter run time.
NOTES: ISU 1014 Lockout Ventilation on Humidification
or Dehumidification Calls is not an option when
you select ASHRAE is Priority.
The ability to lockout ventilation during the "Sleep"
or "Unoccupied" program periods is not an option
when you select ASHRAE is Priority.
Ventilation — Outdoor Condition Lockouts
(ISU 1013)
Ventilation will not operate when outdoor conditions
exceed the lockout settings unless you manually call for
ventilation or Ventilation Priority (ISU 1012) is set to
ASHRAE is Priority and ventilation is needed to meet
ASHRAE. Lockouts can prevent ventilation during extreme
weather conditions to keep humid, hot, and cold air out of
the home.
67 33-00096—04