General
4
MAXXfl o EVO
1.1 DESCRIPTION OF HEATER
This Andrews Water Heaters MAXXfl o EVO is a gas fi red, low NOx, 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 indica-
tion. 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.
The water heater 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.
The water heater is equipped with NTC sensors for precise temperature control on fl ow and return mani-
folds. 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 out-
side via a combined fl ue system (C13, C33, C53 & C63).
The safety and operation functions of the water heater is managed by micro processor controlled circuit
board, modulating the water heater according to the demand. Control is performed using comparison
parameters between the requested temperature and fl ow temperatures from temperature sensors.
C
L
:
When a demand is started (DHW tank sensor is < DHW tank setpoint - Hysteresis), the water heater is
quickly ignited. The controls calculate the charging setpoint (factory standard is DHW tank se
2
O
C) and the heat engine then modulate the pump and burner so that the charging temperature into the
tank does not exceed the charging setpoint by more than 1
O
C.
When the DHW tank setpoint has been reached, the controls will switch off the water heater and the
controls will remain in standby until demand for heat is re-established.
When DHW tank temperature (B3 sensor) < DHW setpoint - DHW Hysteresis, demand will be restarted
and operation as described above, will begin 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
