Controls And Accessories - Dunkirk Q95M-200 Installation, Operation & Maintanance Manual

This section provides a brief description of the key controls and
accessories found in this boiler. See the Repair Parts Manual
(P/N# 240006107) for illustrations and the Control Manual and
Operation Instructions (P/N# 240006104) for a detailed sequence
of operation and troubleshooting procedures.
aluminum heat exchanger
This appliance employs a cast aluminum heat exchanger that
features a monoblock design. The monoblock design eliminates
the need for mating sections and therefore eliminates leaks be-
tween sections. Since the heat exchanger is cast of aluminum
instead of iron, it has better heat transfer properties which in
turn lead to higher efficiency and cooler exhaust temperatures.
These cooler exhaust temperatures create condensation of the
flue gas, which would cause corrosion in traditional cast iron
heat exchangers.
main power switch
This appliance features a main power switch located on the display
panel. The main power switch is illuminated when it is receiving
power and in the ON position. The only time that the switch should
not be illuminated once the boiler is ready for use is when the switch
is in the OFF position.
modulating boiler control
This appliance incorporates an integrated modulating control
that senses the load necessary to heat a structure and therefore
uses less fuel than a conventional fixed firing rate boiler when
there is a lower than peak demand for heat. The control senses
the supply water, return water, and outside air temperatures if
the outside air sensor is connected and calculates the load on
the system. It then adjusts the firing rate to deliver the amount
of heat that is needed at that particular time.
ntc sensors
The NTC sensors used with this appliance for measuring sup-
ply water, return water, and outside air temperature are specially
configured to operate with the modulating boiler control.
Xi - controls and accessories
modulating blower
The modulating blower provides a means of introducing the gas/
air mixture through the burner and into the combustion chamber
where combustion can begin and then out the exhaust vent where
the combustion products are discharged to the outdoors. The
blower is designed to communicate with the modulating control
to run at variable speeds dependent on the heat load experienced
by the heating system. The variable speeds create pressures felt
by the gas valve and gas/air mixer that dictate how much fuel is
introduced to the combustion process.
Gas control valve
The gas controls in this boiler have been developed for domes-
tic heating appliances with premix burners and automatic direct
burner ignition and are suitable for natural and LP gas. The gas
controls perform all the functions required to safely regulate gas
flow to the main burner of the boiler. The gas valve is directly
connected to the gas/air mixer.
Gas/air mixer
The venturi design of the gas/air ensures that there is always the
correct mixture of air and gas.
modulating burner
This burner is designed to operate over the full range of input for
this boiler. The burner can operate under normal (blue flame)
and infrared conditions.
direct spark igniter (dsi)
This appliance uses a DSI to ignite the fuel/air mixture in the
combustion chamber and sense flame during operation. The
DSI is a durable, reliable component that resists breakage due to
handling or inadvertent impact with other objects.
manual reset low water cut off
This appliance employs a factory installed integral low water cut
off (LWCO) that has to be manually reset if there is a low water
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