Water Furnace Versatec Ultra Series, Installation Manual

35

VERSATEC ULTRA SERIES INSTALLATION MANUAL

Over/Under Voltage Shutdown

 - An over/under voltage 

condition exists when the control voltage is outside the 
range of 18 VAC to 30 VAC. If the over/under voltage 
shutdown lasts for 15 minutes, the lockout and alarm relay 
will be energized. Over/under voltage shutdown is self-
resetting in that if the voltage comes back within range 
of 18 VAC to 30 VAC for at least 0.5 seconds, then normal 
operation is restored.

Operation Description

Power Up

 - The unit will not operate until all the inputs and 

safety controls are checked for normal conditions. The unit 
has a 5 to 80 second random start delay at power up. Then 
the compressor has a 4 minute anti-short cycle delay after 
the random start delay.

Standby

 In standby mode, Y1, Y2, W, DH, and G are not 

active. Input O may be active. The blower and compressor 
will be off.

Heating Operation

Single Compressor Heating, 2nd Stage (Y1, Y2)

The compressor will be staged to full capacity 20 seconds 
after Y2 input is received. The ECM blower will shift to high 
speed seconds after the Y2 input is received.

Dual Compressor Heating, 2nd Stage (Y1, Y2)

In dual compressor operation, two ABC boards used in 24 
VAC operation, there will be a Y2 call to the Y1 input on the 
second ABC. The compressor will stage to full capacity 30 
seconds after Y1 input is received to the second board. 

Single Compressor Heating, 3rd Stage (Y1, Y2, W)

The hot water pump is de-energized and the first stage of 
electric heat is energized 10 seconds after the W command 
is received. If the demand continues the second stage of 
electric heat will be energized after 5 minutes.

Dual Compressor Heating, 3rd Stage (Y1, Y2, W)

 - 

The first stage of electric heat is energized 10 seconds 
after the W command is received.  If the demand continues 
the second stage of electric heat will be energized after 5 
minutes

Emergency Heat (W)

 - The blower will be started on “G” 

speed, 10 seconds later the first stage of electric heat will 
be turned on. 5 seconds after the first stage of electric 
heat is energized the blower will shift to Aux speed. If the 
emergency heat demand is not satisfied after 2 minutes the 
second electric heat stage will be energized.

Blower (G)

 - The blower will start immediately upon 

receiving a thermostat G command. If there are no other 
commands from the thermostat the ECM will run on “G” 
speed until the G command is removed. Regardless of 
blower input (G) from the thermostat, the blower will 
remain on for 30 seconds at the end of each heating cycle.

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.

Single Compressor Cooling, 2nd Stage (Y1, Y2, 0)

The compressor will be staged to full capacity 20 seconds 
after Y2 input was received. The ECM blower will shift to high 
speed 15 seconds after the Y2 input was received. 

Dual Compressor Cooling, 2nd Stage (Y1, Y2, O)

In dual compressor operation, two ABC boards used in 24 
VAC operation, there will be a Y2 call to the Y1 input on the 
second ABC. The compressor will stage to full capacity 30 
seconds after Y1 input is received to the second board. 

Blower (G)

 - The blower will start immediately upon 

receiving a thermostat G command. If there are no other 
commands from the thermostat the ECM will run on “G” 
speed until the G command is removed. Regardless of 
blower input (G) from the thermostat, the blower will 
remain on for 30 seconds at the end of each heating, 
cooling, and emergency heat cycle.

Dehumidification (Y1, O, DH or Y1, Y2, O, DH)

 - When a 

DH command is received from the thermostat during a 
compressor call for cooling the ECM blower speed will be 
reduced by 15% to increase dehumidification.

Emergency Shutdown

 - Four (4) seconds after a valid ES 

input, P2-7 is present, all control outputs will be turned off 
and remain off until the emergency shutdown input is no 
longer present. The first time that the compressor is started 
after the control exits the emergency shutdown mode, 
there will be an anti-short cycle delay followed by a random 
start delay. Input must be tied to common to activate.

Continuous Blower Operation

 - The blower output will 

be energized any time the control has a G input present, 
unless the control has an emergency shutdown input 
present. The blower output will be turned off when G input 
is removed.

Load Shed 

- The LS input disables all outputs with the 

exception of the blower output. When the LS input has been 
cleared, the anti-short cycle timer and random start timer 
will be initiated. Input must be tied to common to activate.

Controls - Aurora Base Control cont.