ENVISION RESIDENTIAL INSTALLATION MANUAL
Microprocessor Control (cont.)
Heat, 3rd Stage (Y1,Y2,W) Dual Capacity Units
The hot water pump is
Emergency Heat (W only)
The fan is started on high speed, and the first stage of resistance heat is energized 10 seconds after the "W" input. Continuing demand will engage the additional stages of resistance heat sequentially every 2 minutes.
Cooling Operation
In all cooling operations, the reversing valve directly tracks the “O” input. Thus, anytime the “O” input is present, the reversing valve will be energized.
Cool, 1st Stage (Y1,O)
The blower motor and hot water pump are started immediately, the loop pump(s) is energized 5 seconds after the “Y1” input is received. The compressor will be energized (on low capacity for Dual Capacity units) 10 seconds after the “Y1” input. The ECM blower will shift from low to medium speed 15 seconds after the “Y1” input (85% of medium speed if in dehumidification mode).
Cool, 2nd Stage (Y1, Y2, O) Single Speed Units
The fan changes to high speed (85% of high speed if in dehumidification mode) 15 seconds after the “Y2” input (ECM only).
Cool, 2nd Stage (Y1, Y2, O) Dual Capacity Units
The second stage compressor will be activated 5 seconds after receiving a “Y2” input as long as the minimum first stage compressor run time of 1 minute has expired. The ECM blower changes to high speed 15 seconds after the “Y2” input (85% of high speed if in dehumidification mode). The Comfort Alert will delay the second stage compressor until 5 seconds after it receives a “Y2” from the board.
Lockout Conditions
During lockout mode, the appropriate unit and thermostat lockout LEDs will illuminate. The compressor, loop pump, hot water pump, and accessory outputs are
Comfort Alert lockouts cannot be reset at the thermostat. All other lockout modes can be reset at the thermostat after turning the unit off, then on, which restores normal operation but keeps the unit lockout LED illuminated. Interruption of power to the unit will reset a lockout without a waiting period and clear all lockout LEDs.
High Pressure
This lockout mode occurs when the normally closed safety switch is opened momentarily (set at 600 PSI).
Low Pressure
This lockout mode occurs when the normally closed low pressure switch is opened for 30 continuous seconds (set at 40 PSI). A low pressure fault may also be indicated when a Comfort Alert lockout has occurred.
Freeze Sensing (Water Flow)
This lockout mode occurs when the freeze thermistor temperature is at or below the selected freeze sensing point (well 30°F or loop 15°F) for 30 continuous seconds.
Condensate Overflow
This lockout mode occurs when the condensate overflow level has been reached for 30 continuous seconds.
Fan RPM
The control board monitors fan RPM to sense operation. This lockout mode occurs if the fan RPM falls below the low RPM limit (100 RPM) for 30 continuous seconds (ICM only).
Fan (G only)
The fan starts on low speed (PSC ON). Regardless of fan
input “G” from thermostat, the fan will remain on low speed for 30 seconds at the end of each heating, cooling or emergency heat cycle.
A DIP switch on the Envision control allows field selection of 15% reduced fan speeds for cooling in the dehumidification mode or medium and high fan speeds for cooling in the normal mode.
Note: Fan speed can change automatically only with an ECM Motor.
ECM2 Airflow Selection DIP Switches (SW1)
A
Only three of the DIP switches can be in the “on” position. The first “on” switch (the lowest position number) determines the “low speed fan” setting. The second “on” switch determines the “medium speed fan” setting, and the third “on” switch determines the “high speed fan” setting, (see page 15).
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