Install Instructions

33
Tech.Doc - 03/21 - Subject to change. © Belimo Aircontrols (USA), Inc.
ZIP Economizer
Method of Operation
States
Virgin State
The ZIP Economizer comes shipped from the factory in this state.
“Setup Incomplete” will be displayed. No control will occur until setup is
completed.
Automatic State
– all of the following strategies and operational modes
are available in this state.
A minimum of two pieces of information (in level 2 Settings menu) must
be entered before the ZIP Economizer will go into Automatic State:
• The appropriate ZIP code must be entered.
• The minimum damper position setpoint (Vent Min Pos) percentage
must be entered.
When in Automatic State, the G input terminal is used to monitor a
remote occupancy contact, time clock and/or indoor fan signal. When
the G terminal is energized, the ZIP Economizer will operate in Occupied
(damper will move to the proper ventilation position). Otherwise, the ZIP
Economizer will operate in Unoccupied.
Strategies
Compressor Protection and Energy Savings
DXLL
(Supply Air Low Temperature Protection in Mechanical Cooling)
This strategy is activated automatically when in Mechanical Cooling
Mode depending on supply air temperature. Timers, temperature dead
bands and SAT Y2 Limit setting all interact with this strategy.
SAT < 45°F
All compressor stages disabled.
45 °F ≤ SAT < 47°F
Compressor stages may or may
not be enabled based on whether
or not SAT is rising or falling.
SAT ≥ 47°F and SAT Y2 Limit=Off
Both compressor stages enabled.
47°F ≤ SAT < 56.5°F and SAT Y2
Limit=On
1st stage compressor enabled.
2nd stage compressor disabled.
SAT ≥ 56.5°F
Both compressor stages enabled.
SAT Y2 Limit
This strategy inhibits the 2nd stage compressor from coming on
prematurely based on SAT temperature and time.
• IF Y2 is energized
AND Compressor 1 has been running for less than 4 minutes
AND Supply Air Temp is less than or equal to its required setpoint +
1.5° (56.5°F)
THEN Compressor 2 will not be allowed to come on
LCLO (Low Ambient Compressor Lockout)
This strategy inhibits compressor operation at low outdoor air
temperatures.
• IF OAT falls below the low limit (50°F) adjustable (40...65°F)
AND not in Heat Pump Mode
THEN Compressor 1 and Compressor 2 will be disabled.
• IF OAT rises 2°F above the low limit of LCLO setpoint
OR in Heat Pump Mode
THEN Compressor 1 and Compressor 2 will be enabled.
Minimum On and Minimum Off Time
This strategy prevents the compressors from “short-cycling”.
• IF any Compressor is energized
THEN run it at least 180 seconds EXCEPT when entering Brownout
Mode when compressors will be shut off immediately.
• IF any Compressor is de-energized
THEN keep it off for at least 180 seconds
Not Simultaneous ON/Not Simultaneous OFF
On RTUs with 2 compressors this strategy is used to prevent both
compressors from coming on at the same instant to keep electrical
demand down.
• Compressors 1, 2 are kept from switching on together by a 10 second
time delay.
• If SAT Y2 Limit is set to “On” compressor 2 is delayed by 240 seconds
to evaluate if the single compressor already operating can bring SAT
less than or equal to setpoint +1.5 °F (56.5°F).
• Compressors 1, 2 are kept from switching off together by a 5 second
time delay EXCEPT when entering Brownout when compressors will
be shut off immediately.
Brownout Protection
Input power (AC 24 V) is monitored.
• IF input voltage drops to 75%
AND it stays below there for 30 seconds
THEN Brownout will be enabled.
• IF input voltage rises to 85%
AND it stays there for 300 seconds
THEN Brownout will be disabled.
Under Brownout conditions the current operating mode will be
maintained EXCEPT Mechanical Cooling and Integrated Cooling (where
compressors are utilized).
Instead of Mechanical Cooling it will go to Ventilation, DCV or
Unoccupied. Instead of Integrated Cooling it will go to Free Cooling.
This strategy prevents compressor operation during brownout
conditions. Compressors will be turned off immediately (bypassing
minimum on/off timers).
Random On Delay after Power Up
After a power blackout or any power restore, compressors will go
through a random time delay before allowing them to operate. This
random timer is between 30...180 seconds. This helps the electrical
network to come back up without excessive demand from multiple RTUs
and compressors coming back on after the blackout.
Freeze Protection
See Freeze Protection Mode of Operation on page 36.