Section 12 - Sensors for Economizer Modules
63-8594-02 Honeywell Economizers 160
In differential mode the signal from the dry
bulb analog sensor to the economizer is 10 to
20 mA so the economizer can choose the
higher output (indicates lower temperature)
and can choose which temperature is better.
Lets look at an example: When using a C7650
and the C setting is chosen on the economizer
logic module, the module will open the outside
air damper at approximately 58F. When the
temperature is rising, the module will allow
free cooling until the temperature reaches 68F.
At this point the module will determine the
outdoor temperature is no longer good for free
cooling and will turn on the mechanical
cooling. The temperature needs to drop to
below 58F for the economizer to reset and
allow free cooling without mechanical cooling
again UNLESS the power is turned off to the
economizer and the economizer is allowed to
reset.
The C7660 sensor was developed to
eliminate the 10 degree F deadband issue
using the C7650 in single dry bulb
applications. When using single with
Honeywell legacy economizers, replace the
C7650 with the C7660. The C7660 has a 3
position switch used for setting the outdoor
changeover temperature. There are 8 user
selectable changeover temperatures: 48F,
53F, 55F, 58F, 63F, 68F, 73F, or 78F with a +/-
1F hysteresis around the selection
temperature. If you change the temperature
change over setpoint the change is made in
real time so you can reset the changeover
temperature without recycling power.
C7046 Temperature
C7150 Temperature
C7632A
Carbon Dioxide
C7232A
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