General
4
MAXXfl o EVO 150/302
1.1 DESCRIPTION OF HEATER
This Andrews Water Heaters MAXXfl o EVO is a gas fi red, low NOx, twin heat engine, cascading, direct fi red
water heater, with an integrated stainless steel tank.
Fully automatic electronic controls are integrated into the heater, with a wide range of control and sensor
options available. The controls also provides voltage free outputs for Enable, Burner On and fault indication.
Full BMS integration is available through the use of Modbus and optional protocol devices.
Access to the controls of the heater via the Internet and/or mobile phone app, is possible through an optional
web server device available from Andrews Water Heaters.
Each heat engine module consists of a stainless steel combustion chamber, premix burner, modulating fan,
gas valve, ignition and fl ame detection electrodes, water pressure sensor and a NTC fl ue sensor for safety
supervision.
Each heat engine module is equipped with NTC sensors for precise temperature control on fl ow and return
manifolds. Fully premixed, radiating, modulating burner, integrated with gas valve to deliver precise gas/air
mixture throughout the full modulation range.
Common combustion air intake manifold, takes air from boiler room (type B23 fl ue) or directly from outside
via a combined fl ue system (C13, C33, C53 & C63).
The safety and operation functions of each heat engine are managed by micro processor controlled circuit
boards, one for each heat engine. The upper controller also acts as the cascade master controller, modu-
lating the heat engines according to the demand, based on data from the systems sensors. Control is per-
formed using comparison parameters between the requested temperature and the global fl ow temperature.
C
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When a demand is started (the sensor of the DHW tank is less than the set point of the DHW tank - Hyster-
esis), the heat engine is ignited quickly (in the case of the MAXXfl o EVO 150 the second heat engine starts
approximately 60 seconds after the fi rst heat engine ignition). The controls calculate the charge setpoint (fac-
tory standard is the setpoint of the DHW tank) and the heat engine(s) modulate the pump(s) and burner(s) so
that the charge temperature in the tank does not exceed the charge set point.
When the temperature at B3 sensor equals the set point of the DHW tank, the burner(s) are switched off dur-
ing operation and the control elements remain in stand-by until the heat demand is restored.
If the temperature of the DHW tank (B3 sensor) is less than the DHW setpoint - DHW hysteresis, the de-
mand will be restarted and the operation as described above will start again.
1.2 FOR WHOM IS THIS MANUAL INTENDED?
This manual is intended for the heating specialist who installs commercial / industrial heating plant and
equipment.
1.0 GENERAL & SAFETY INFORMATION
Содержание 7800597
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