5292230-USG-B-0718
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RRS Economizer Controller Quick Start Guide
enthalpy if [Return Temp] and [Return Humidity] inputs
are available; the free cooling changeover method is
determined by the availability of [Outdoor Humidity] input
• The free cooling changeover method is single
enthalpy if [Outdoor Temp] and [Outdoor Humid-
ity] 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
•
With [Free Clg Select] set to “Dry Bulb Temperature” –
the free cooling changeover method will not advance to
single enthalpy or dual enthalpy if [Outdoor Humidity],
[Return Temp] and [Return Humidity] inputs are avail-
able; the free cooling changeover method is dry bulb
For all [Free Clg Select] settings, free cooling operation is not
permitted if [Outdoor Temp] input is not available.
Dry bulb free cooling changeover is based on the [Outdoor
Temp]. Dry bulb is the “standard option” free cooling change-
over method for the RRS Economizer Controller since the
included OAT/OAH sensor is the source for [Outdoor Temp]
but requires the [Free Clg Select] setting to be changed from
the default “Auto” to “Dry Bulb Temperature”. Dry bulb is also
the “fallback” free cooling changeover method since enthalpy
free cooling changeover methods can revert to dry bulb if
humidity inputs are not available. As a “best practice”, it is
recommended that the [Dry Bulb Stpt] be reviewed and have
a reasonable “fallback” setting for the application regardless
of the desired free cooling changeover method. When “Dry
Bulb Temperature” is the active free cooling changeover
method:
•
[Free Clg Avail] will indicate “Yes” when both
• [Outdoor Temp] is at or below the [High OA Shut-
off] setting
• [Outdoor Air Enthalpy] falls 1 “B/#” or more below
the [OA Enth Setpt] setting
•
[Free Clg Avail] will indicate “No” when either
• [Outdoor Temp] rises above the [High OA Shutoff]
setting
• [Outdoor Air Enthalpy] rises above the [OA Enth
Setpt] setting
Dual enthalpy free cooling changeover requires addition of
the optional return air temperature and humidity sensor. Dual
enthalpy free cooling changeover is based on a comparison
of the [Outdoor Air Enthalpy] to the [Return Air Enthalpy].
[Outdoor Air Enthalpy] is calculated from the [Outdoor Temp]
and the [Outdoor Humidity] inputs. [Return Air Enthalpy] is
calculated from the [Return Temp] and the [Return Humidity]
inputs. When “Single Enthalpy” is the active free cooling
changeover method:
•
[Free Clg Avail] will indicate “Yes” when both
• [Outdoor Temp] is at or below the [High OA Shut-
off] setting
• [Outdoor Air Enthalpy] falls 1 “B/#” or more below
the [Return Air Enthalpy]
•
[Free Clg Avail] will indicate “No” when either
• [Outdoor Temp] rises above the [High OA Shutoff]
setting
• [Outdoor Air Enthalpy] rises above the [Return Air
Enthalpy]
FREE COOLING OPERATION
Free cooling operation is initiated when both:
•
There is 24 volts AC input to the RRS Economizer Con-
troller Y1 pin ([Y1-Tstat] indicates “On”)
• 24 volts AC originating from thermostat input to
the Simplicity Lite Y1 screw terminal, through the
Simplicity Lite Y1 output pin to the RRS Econo-
mizer Controller Y1 pin input
•
[Free Clg Avail] indicates “Yes”
NOTE:
Compressor operation by Simplicity Lite to supple-
ment free cooling operation by the RRS Economizer
Controller is available when a 2-stage cooling ther-
mostat is used to provide input to the Simplicity Lite
Y2 terminal. Other than the influence on the RRS
Economizer Controller supply air temperature input,
Simplicity Lite compressor operation from Y2 input
is independent of free cooling operation.
During free cooling operation:
•
The RRS Economizer Controller Y1O pin output is de-
energized ([Compressor 1] indicates “Off”)
• Simplicity Lite will display flash code 11 and com-
pressor operation from Y1 thermostat/ECON input
ends.
•
The [Damper Command] is increased if [Supply Temp] is
more than 0.5°F above the [Supply Temp Stpt]
• Free cooling operation can increase the [Damper
Command] up to “100.0 %”
•
The [Damper Command] remains at the current position
if [Supply Temp] is within 0.5°F above or below the [Sup-
ply Temp Stpt]
•
The [Damper Command] is decreased if [Supply Temp]
is more than 0.5°F below the [Supply Temp Stpt]
• If [Occupancy] indicates “Occupied”, free cooling
operation can decrease the [Damper Command]
to the active minimum position value
