Camus Hydronics Avenger Series - 5.3 ELECTRONIC LOW AIR PRESSURE SWITCH (DIFFERENTIAL)

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• To avoid serious damage, DO NOT ENERGIZE the appliance until the system is full of water. Ensure that all air is removed from
the heat exchanger pump housing and piping before beginning initial operation. Serious damage may result if the appliance is
operated prior to purging of all air.
• Provide the appliance with proper overload protection.
5.2 VARIABLE FREQUENCY DRIVE
This appliance uses a VFD which provides power to the combustion fan. The fan motor operates on 230VAC 3 phase power. This three
phase voltage is generated by the VFD and supplied directly to the fan motor. The VFD receives a 4-20mA modulating signal from the
SOLA to vary the frequency of the voltage supplied to the fan motor. This varies the output of the combustion air fan from 4% up to 100%
of capacity corresponding to the same variation in burner input. Once the ‘self-checks’ are completed by the SOLA, the VFD is provided
with a signal to operate at soft start level for initial burner ignition. After main burner ignition is established, the modulating signal is
generated by the VFD to vary fan speed based on desired water temperature set point.
CAUTION
The voltage output from the variable frequency drive to the combustion air fan is 230VAC, 3 Phase. AVOID contact with high
voltage wiring.
5.3 ELECTRONIC LOW AIR PRESSURE SWITCH (DIFFERENTIAL)
A pressure transducer coupled with an electronic controller is used to prove operation of the combustion air fan on. The pressure switch
sensing points are installed at the fan intake. One point measures total pressure (+air) and is connected to a pitot tube facing the flow.
The other point measures static pressure. Differential pressure at the switch will be affected by blockages in the intake pipe or at the flue
discharge. A minimum differential pressure across the sensing points of the pressure switch proves operation of the combustion air fan.
The diagnostics display will exhibit a status of an open Interrupted Air Switch (LCI OFF) when the differential pressure switch detects a
sustained low air condition. This condition could be caused by several factors including:
• Sensing line broken or loose fitting
• Dirty filter or blocked vent
• Steady high wind condition
• Incorrectly set switch
The staging relay utilizes 4 individual relays:
Relay 1: operates the High-End Gas Valve and the air inlet damper.
Relay 2 and 3: activate/deactivate the hot surface igniter during the gas valve transition sequence.
Relay 4: is dedicated to low air switch operation and ensures that if a low air condition occurs the control will enter into an automatic reset
error.