Controls And Accessories - Dunkirk Q95M-200 Installation 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 illustra-
tions and the Control Manual and Operation Instruc-
tions (P/N# 240006104) for a detailed sequence of
operation and troubleshooting procedures.
ALUMINUM HEAT EXCHANGER
This appliance employs a cast aluminum heat ex-
changer that features a monoblock design. The
monoblock design eliminates the need for mating
sections and therefore eliminates leaks between
sections. Since the heat exchanger is cast of alu-
minum instead of iron, it has better heat transfer
properties which in turn lead to higher efficiency
and cooler exhaust temperatures. These cooler ex-
haust 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 il-
luminated 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 casting temperature safety switch has been
tripped or when the switch is in the OFF position.
MODULATING BOILER CONTROL
This appliance incorporates an integrated modulat-
ing control that senses the load necessary to heat
a structure and therefore uses less fuel than a con-
ventional fixed firing rate boiler when there is a low-
er than peak demand for heat. The control senses
the supply water, return water, and outside air tem-
peratures 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 mea-
suring supply water, return water, and outside air
temperature are specially configured to operate
with the modulating boiler control.
MODULATING BLOWER
The modulating blower provides a means of intro-
ducing the gas/air mixture through the burner and
XI - CONTROLS AND ACCESSORIES
into the combustion chamber where combustion can
begin and then out the exhaust vent where the com-
bustion products are discharged to the outdoors. The
blower is designed to communicate with the modu-
lating 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.
The gas controls in this boiler have been developed
for domestic heating appliances with premix burn-
ers 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.
The venturi design of the gas/air ensures that there
is always the correct mixture of air and gas.
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.
This appliance uses a direct spark igniter to ignite
the fuel/air mixture in the combustion chamber and
16
GAS CONTROL VALVE
GAS/AIR MIXER
MODULATING BURNER
!
WARNING
The burner in this unit contains ceramic fi-
bers which can be converted to a cancer-
causing substance called cristobalite in very
high temperature applications. When remov-
ing the burner, avoid breathing dust by using
a NIOSH (National Institute for Occupational
Safety and Health) certified dust respirator
and wear long-sleeved, loose fitting clothing,
gloves, and eye protection to avoid contact
with skin and eyes. In case of contact with
skin or eyes, wash or irrigate affected area
immediately, then wash potentially contami-
nated clothing separately and rinse clothes
washer thoroughly before reusing. For addi-
tional information, see the NIOSH homep-
age at www.cdc.gov/niosh/homepage.html.
DIRECT SPARK IGNITER
!