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THX9321 PRESTIGE
®
2.0 AND THX9421 PRESTIGE
®
IAQ 2.0 WITH EIM
68-0311—01 76
4. Select the Ventilation Fan Control. See “Ventilation Fan
Control (ISU 10060)” on page 74 for more information.
See Fig. 147.
NOTE: ISU 10060 is only displayed if the Ventilation
Type is ERV / HRV. The thermostat controls the
fan if the Ventilation Type is Fresh Air Damper.
Fig. 147.
5. If ASHRAE was selected for ISU 10050, select the Num-
ber of Bedrooms and Size of House. See Fig. 148.
Fig. 148.
6. If ASHRAE was selected for ISU 10050, enter the Equip-
ment Ventilation Rate (CFM). Be sure this setting corre-
sponds with the actual ventilator speed. This setting
determines how often the ventilation equipment will oper-
ate to meet the ASHRAE 62.2 Standard. The thermostat
will indicate the following based on the Equipment Venti-
lation Rate, Square Footage and Number of Bedrooms.
See Fig. 149.
• Provides an indication if it meets or does not meet the
ASHRAE 62.2 Standard.
• Provides% run time that is needed to meet the
ASHRAE 62.2 Standard.
Fig. 149.
7. Select a Ventilation Priority (see Fig. 150):
a. Lockouts are Priority: The thermostat places a pri-
ority on lockouts versus the ASHRAE 62.2 ventilation
standard. The thermostat will not run ventilation dur-
ing the following lockout conditions (if configured)
unless you manually call for ventilation:
(1) Lockout Ventilation during Outdoor Conditions
(ISU 10130)
(2) Lockout Ventilation on Humidification or Dehu-
midification Calls (ISU 10140)
(3) Lockout Ventilation during “Sleep” (Residential) or
“Unoccupied” (Commercial) program periods.
Note: This option is set by the user on the Ventila-
tion screen in the Menu.
b. ASHRAE is Priority: ASHRAE requires additional
ventilation following a long off cycle. The thermostat
meets the ASHRAE 62.2 ventilation standard by run-
ning additional ventilation when outdoor conditions
are favorable. If ASHRAE cannot be met when out-
door 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.
NOTE: ISU 10140 “Lockout Ventilation on Humidifica-
tion 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 Prior-
ity”.