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Front LED Indicator Lights
The LED indicator lights on the front cover allow for fast, easy
identification of real time system conditions.
• Green PWR – solid = normal, 24VAC power
• 1 blink, bad BT sensor
• 2 blinks, bad OT sensor
• Status
• On = electric mode
• Off = standby (SB) or switchover
• Fast pulsing = Geo unit ICM board fault
• Slow pulsing = cool mode
• Fast pulsing with green LED off = mode switch
incorrectly set
• HP-STAGE1
• On = logic board is actively calling for heat pump stage 1
• Off = no requirement for heat pump stage 1 exists
• HP-STAGE2
• On = logic board is actively calling for heat pump stage 2
• Off = no requirement for heat pump stage 2 exists
• Thermostat (forced air only)
• On = room thermostat actively calling (heating or cooling)
• Off = no room thermostat demand
• STANDBY
• On = system is actively calling for backup heating source
• Off = system is in heat pump mode
Front panel stand-by/ electric switch (Mode B and C Only) – allows the user to condition the system to
select an energy source. This can be used for repair or troubleshooting of the furnace or simply "Power of
Choice" selection.
Enable / Disable switch – In some applications, it is advantageous to lockout the heat pump in times when it
use will not be required. Example would be cooling season with no cooling load in the HVAC system.
• With the switch in enable, the heat pump is enabled to operate based on room thermostat.
• With the switch in disable, the heat pump is disabled.
Buffer Tank Turn-Over
One of the challenges involved in the operation of a hydronic buffer tank system is the inability to quickly and
efficiently change the system over from a heating system to a cooling system and vice versa.
During the buffer tank turn-over, the coil pump is disabled if water in the buffer tank is between the
temperatures of 60°F and 80°F.
Air Stat W and Y Collision
IMPORTANT: It is important for the end user to understand that after the heating season, the first "Y" (cooling) call
To eliminate the possibility of simultaneous, conflicting signals, a 7 second delay is active after the completion
switches the system to the cooling mode, beginning the process of lowering the temperature of the fluid in the buffer
of a W or Y call. At the completion of the delay, the controller can once again accept W oar Y calls.
tank. Likewise, the first "W" after a series of "Y" calls sets in motion the sequence for heat or hot water. Since this
"buffer tank turn-over" requires a substantial amount of energy, the frequency of this operation should be held to a
minimum.
02/22/2012
Buffer Tank Operation
16
HI114
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