Nordair Niche DH2 150, Инструкция по установке, наладке и обслуживанию, Страница: 6 / 26

Introduction
The Nordair Niche DV/DH Direct Fired
air handling unit is designed for
economical and efficient operation to
give clean and healthy environmental
conditions, with constant even
temperature control. It is available as a
standard full fresh air unit only.
The two versions of the heater feature a
burner mounted in an air handling unit.
The burner is especially designed so
that a proportion of the incoming air is
forced into contact with the flame to
ensure rapid mixing and uniform heating
to the desired temperature. Each heater
is supplied complete with automatic
safety and temperature control systems.
These systems are pre-piped, wired and
checked before despatch.
Gas burner assembly
Each burner is built up from modular
components to give the required heat
duty. The burner consists of a heavy
duty iron body which forms the fuel gas
manifold, fitted with stainless steel
mixing plates carefully designed to
withstand the stresses of thermal
expansion. The mixing plates are
perforated to ensure intimate and
progressive mixing of the incoming air
with the fuel gas at all firing rates.
Heater casing
The heater casing comprises of an
aluminium pentapost frame construction
with 1.2mm ‘Alunzink’ single skin panels.
The casing incorporates an internal
burner profile opening and mild steel
angle support.
The unit is fitted with removable/hinged
access panels in the side of the heater
for inspection internally of the fan, motor
and burner module.
The DV vertical configuration heaters
are a ‘blow through’ type, where the fan
unit is situated within the base of the unit
and blows the air over the burner.
The DH horizontal configuration heater
are a ‘pull through’ type where the fan,
unit is situated on the downstream side
of burner with the air being drawn
through the burner.
Control sequence
The time/temperature control of the
heater will be carried out by either a
Ambi-Tec electronic control panel, or a
Ambi-Stat AS1 thermostat panel.
Ambi-Tec control panel
The Ambi-Tec electronic controller
contains a digital display panel for
monitoring/controlling the following
heater functions. Outside of occupancy
time a frost set point will start up the
heater if the space temperature falls
below the desired frost protection
temperature.
During occupancy time and below room
set point (say 19
˚
C adjustable) the
heater discharge air temperature is
controlled at a constant 40
˚
C by means
of a active duct sensor modulating the
gas throughput control valve.
At 1
˚
C above room set point the
discharge air temperature is reset to
25
˚
C (Adjustable) and maintained again
by modulating the gas throughput
control valve. Reducing the discharge
air temperatures to 25
˚
C eliminates
stratification, and provides an even
temperature both laterally and vertically
throughout the space. At 3
˚
C adjustable
up to 6
˚
C) above room set point, the gas
burner shuts off, and the fan only is
allowed to run.
Ambi-Stat control panel
The Ambi-Stat control panel, comprises
of a seven day electronic time clock,
room and frost thermostats, Heat/Vent
select switch and lockout indication and
reset, incorporated into a sheet steel
enclosure.
Outside of time schedule the heater will
operate under the dictates of the frost
stat to maintain the desired frost
protection temperature.
During occupancy time, and below the
room set point the heater is controlled
via the room thermostat. The heater will
discharge air at a constant 40
˚
C by
means of a active duct sensor
modulating the gas throughput control
valve.
At room set point the heater shuts off,
and will not restart until the room
temperature falls below the room
thermostat setting.
The Heat/Vent switch will during
occupancy times, switch the burner off in
the vent position allowing the air fan to
operate.
In the event of the heater locking out, an
indication lamp will energise on the
control panel, and can be reset by
depressing the switch.
Control panel
The heater control panel incorporates
a Satronic flame programmer,
necessary MCB, contactors, relays,
illuminated push button etc. All
pre-wired to a terminal rail.
Burner sequence
The purge, ignition and main flame
stages of the burner are carried out via
Satronic MMI 810-1 approved flame
programmer.
Overheat
In the event of an over-heat condition,
within the heater casing, the heater is
fitted with over temperature protection,
which has to be manually reset if
acted. By depressing the red button
on the honeywell overheat thermostat.
Safety interlocks
The DH/DV heater includes the
following safety interlocks:
1. Low air differential pressure switch.
2. Overheat controller.
3. Lockout on flame failure/or air
pressure failure.
Site wiring
Site wiring requires the connection of:
1. 415 volt 3 phase 50Hz 4 wire
supply to the main heater control
panel.
2. Duct sensor, room sensor.
General description