andrews COMBIflo 100/300, Installation, Operation And Maintenance Manual

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ANDREWS COMBIfl o 2 GB
1.1 DESCRIPTION OF APPLIANCE
This Andrews COMBIfl o is a gas fi red, low No×, multi- heat engine cascading boiler system, with an
integrated 5” Low Loss Header for the supply of a low temperature hot water space heating system. The
COMBIfl o range of appliances also features an integrated stainless steel tank and plate heat exchanger
for the supply of hot water.
Fully automatic electronic controls are integrated into the appliance, with a wide range of control and
sensor options available. The controls also provides voltage free outputs for Enable, Burner On, Fault
and 0-10V input for remote BMS use. Access to the controls of the appliance via the Internet and/or mo-
bile phone app, is available through an optional device 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 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 re-
turn 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). An air control non-return fl ap is integrated into the air
supply of each heat engine, to ensure that fl ue products cannot contaminate the air supply, when a heat
engine is not in operation.
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 controller, switch-
ing/modulating the heat engines according to the demand and data from the systems sensors. Control is
performed using comparison parameters between the requested temperature and the global fl ow tem-
perature.
Control Logic:
At full demand, each heat engine is ignited one at a time, until all heat engines are operating at full
output. As fl ow and return temperatures increase, all heat engines will begin to modulate down together,
until all are operating at minimum input rate. As fl ow temperatures begin to approach the calculated set
point, one of the heat engines will stop, leaving the others operating at minimum input rate. This will con-
tinue until all heat engines have stopped and temperature fl ow requirements have been fully satisfi ed.
1.2 FOR WHOM IS THIS MANUAL INTENDED?
This manual is intended for the heating specialist who installs commercial/industrial heating plant and
equipment.