5292230-USG-B-0718
RRS Economizer Controller Quick Start Guide 15
effectively disabled if the [Damper Min Pos] is set to the mini-
mum setting of “.0 %”.
FREE COOLING FUNCTIONS
Free cooling functions are disabled, but minimum position
functions remain enabled, when [Econ Enabled] is set to
“No”.
The following are required for free cooling functions to be
effective:
• [Econ Enabled] must be set to “Yes”
• [Outdoor Temp] cannot indicate “Out of range high”
• [Supply Temp] cannot indicate “Out of range high”
• There is 24 volts AC input to the RRS Economizer Con-
troller Y1 pin ([Y1-Tstat] indicates “On”)
Then, the free cooling function is active when the outdoor air
is suitable to use for cooling as determined by the free cool-
ing changeover method in use.
FREE COOLING CHANGEOVER
Free cooling changeover determines if the outdoor air is suit-
able to use for cooling. The method of free cooling change-
over depends on the sensor inputs available and/or on the
selection for the [Free Clg Select] parameter. The free cool-
ing changeover method may be from outside air dry bulb tem-
perature, outside air (single) enthalpy, or a comparison of
return and outside air (dual) enthalpy. A “Yes” value for [Free
Clg Avail] indicates the outdoor air is suitable to use for cool-
ing for the free cooling changeover method in current use.
The [Altitude] configuration item must be set for the nearest
100 feet of job site elevation for best control accuracy when
enthalpy changeover methods are used.
The outdoor air temperature and humidity sensor included
with the economizer accessory provides input to the control-
ler OAT ([Outdoor Temp]) and OAH ([Outdoor Humidity]) pins
for dry bulb and single enthalpy free cooling changeover
capabilities. The optional return air temperature and humidity
sensor provides input to the controller RAT ([Return Temp])
and RAH ([Return Humidity]) pins for the addition of dual
enthalpy free cooling changeover capabilities. Once sensor
presence has been detected and remains in range – the sen-
sor parameter does not indicate “Out of range low” or “Out of
range high” – the sensor input is available for use in free cool-
ing changeover.
The selection for the [Free Clg Select] parameter determines
the desired free cooling changeover method and limits for
advancement the free cooling changeover method:
• With [Free Clg Select] set to “Auto” – the free cooling
changeover method is determined by the temperature
and humidity inputs
• The free cooling changeover method is dual
enthalpy if [Outdoor Temp], [Outdoor Humidity],
[Return Temp] and [Return Humidity] inputs are
available
• The free cooling changeover method will revert to
single enthalpy if either [Return Temp] or [Return
Humidity] input is not available
• The free cooling changeover method will revert to
dry bulb if [Outdoor Humidity] input is not available
• The free cooling changeover method is single
enthalpy if only [Outdoor Temp] and [Outdoor
Humidity] inputs are available
• The free cooling changeover method will advance
to dual enthalpy if both [Return Temp] and [Return
Humidity] inputs are available
• The free cooling changeover method will revert to
dry bulb if [Outdoor Humidity] input
is not available
• The free cooling changeover method is dry bulb if
only [Outdoor Temp] input is available
• The free cooling changeover method will advance
to single enthalpy if [Outdoor Humidity] input is
available
• The free cooling changeover method will advance
to dual enthalpy if [Outdoor Humidity], [Return
Temp] and [Return Humidity] inputs are available
• With [Free Clg Select] set to “Dual Enthalpy” – the free
cooling changeover method remains determined by the
temperature and humidity inputs
• The free cooling changeover method is dual
enthalpy if [Outdoor Temp], [Outdoor Humidity],
[Return Temp] and [Return Humidity] inputs are
available
• The free cooling changeover method will revert to
single enthalpy if either [Return Temp] or [Return
Humidity] input is not available
• The free cooling changeover method will revert to
dry bulb if [Outdoor Humidity] input is not available
• The free cooling changeover method is single
enthalpy if only [Outdoor Temp] and [Outdoor
Humidity] inputs are available
• The free cooling changeover method will advance
to dual enthalpy if both [Return Temp] and [Return
Humidity] inputs are available
• The free cooling changeover method will revert to
dry bulb if [Outdoor Humidity] input is not available
• The free cooling changeover method is dry bulb if
only [Outdoor Temp] input is available
• The free cooling changeover method will advance
to single enthalpy if [Outdoor Humidity] input is
available
• The free cooling changeover method will advance
to dual enthalpy if [Outdoor Humidity], [Return
Temp] and [Return Humidity] inputs are available
• With [Free Clg Select] set to “Single Enthalpy” – the free
cooling changeover method will not advance to dual