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RATER/INSPECTOR VERIFICATION
To verify the ventilation time setting, press the Select button to scroll through the calculated
Required Continuous CFM and the Measured CFM for this installation. If any value does not
match the expected value, the Set Up Menu must be entered to change the floor area, number of
bedrooms or measured cfm.
The calculation used for the ventilation time setting is (all calculations compliant with ASHRAE
Standard 62.2-2010):
)
Required Continuous CFM
Measured CFM
(
Minutes per Hour = 60 *
Required Continuous CFM = ((Floor Area ft2*.01) + (No. of Bedrooms + 1) *7.5)
Measured CFM is entered during set up and Required Continuous CFM is calculated according to
the equation below:
SEQUENCE OF OPERATION – “CODE” SETTING
The control will turn on ventilation with a heating, cooling or fan call for the set number of minutes
during a one-hour cycle period. If the outdoor temperature is above the high temperature ventilation
limit, ventilation will not occur with a cool or fan call, but if it is below the low temperature ventilation
limit it will occur with a heat call. If the HVAC equipment does not turn on enough to meet the
ventilation time within the hour, the control will turn on ventilation without a call, if the outdoor air
temperature is within the high and low ventilation temperature limits. The control will also turn on the
HVAC system blower, if wired and set up to do so.
If the outdoor temperature exceeds the limits set at the end of the first hour, then no additional
ventilation will occur for another 60 minutes, and the cycle period will automatically adjust to four
hours. When the ventilator starts again, it will sample the air temperature and if in range, will meet
the set amount of ventilation during the four-hour cycle period. For example, if the Vent Time was set
to 25 minutes per hour and the air temperature fell below the low limit setting ventilation would only
occur during a heating call. If the heating only operated for 10 minutes during the hour, the control will
automatically change the cycle period to four hours and work to provide the additional 90 total minutes
of ventilation (25 min/hr *4 hours = 100 minutes, minus the 10 minutes of ventilation that occurred
during heating) during the four-hour cycle period.
If the air temperature is still out of range, the control will automatically switch to an 8-hour cycle
period, then a 12-hour cycle period and finally a 24-hour cycle period. During 8, 12 and 24 hour cycle
periods, the total ventilation time increases to compensate for ventilation effectiveness as defined in
ASHRAE Standard 62.2-2010. When the cycle period automatically adjusts to 24-hours, the control will
turn on ventilation to meet the requirements even if the temperature is outside of the set limits.
SEQUENCE OF OPERATION – “COMFORT” SETTING
The control will turn on ventilation with a heating, cooling or fan call by the HVAC equipment, if the
outdoor air temperature is within the high and low ventilation temperature limits and the indoor RH
is within the high and low RH limits, for the set number of minutes during a one-hour cycle period. If
the HVAC equipment does not turn on enough to meet the ventilation time within the hour, the control
will turn on ventilation without a call, if the outdoor air temperature and indoor RH is within the set
limits. The control will also turn on the HVAC system blower, if wired and set up to do so. If the outdoor
temperature or indoor RH are outside of the set limits, then no ventilation will occur.
