Gas Train And Controls; Ratio Gas Valve; Venting Of Gas Valves And Pressure Switches; Burner - Camus Hydronics DynaFlame DFW501 Installation, Operation And Service Manual

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If the appliance will not light off and the blue 'main
flame' light is coming on but not staying on then it will
be necessary to adjust the low fire as explained in the
detailed start-up procedure.
3.8

GAS TRAIN AND CONTROLS

Figure 9: Typical Gas Train
3.9

RATIO GAS VALVE

Figure 10: 1:1 Air/Gas Ratio Control Valve
The main gas valve supplying gas to the burner on this
appliance utilizes a pressure regulating electro hydraulic
actuator providing a slow opening, fast closing safety shut
off and air/gas ratio control for the gas combustion process.
This gas valve controls the pressure difference across the
restriction in the gas supply line as a function of the
pressure difference across the combustion air supply to the
burner. The actuator maintains a constant air to gas ratio as
the volume of air changes based on the operation of the
combustion air fan. The valve is a 1:1 differential pressure
air/gas ratio controller. The valve generates the same
pressure difference on the gas side as it senses on the air
side. The valve performs the functions of pressure
regulator, safety shutoff, and air/gas ratio control. Slow
opening and safety shutoff is accomplished by operation of
an electro hydraulic cylinder. Full closing of the valve seat
occurs in less than 0.8 seconds when the valve is de-
energized. A visual stroke position indicator is provided on
the valve assembly to indicate the position of the valve
seat. Operation of the gas valve in combination with the
combustion air fan allows the burner input rate to vary from
20% to 100% based on temperature demand. The inlet gas
supply pressure must be maintained within the specified
minimum and maximum pressures. A reduction of up to
30% is permitted in the inlet gas pressure between light off
and full fire conditions.
The manifold differential pressure is preset at the factory
and adjustment is not usually required if gas supply
pressure is maintained within the specified range. If the
manifold differential pressure is to be measured, follow the
"Gas Manifold Pressure Measurement Procedure" for
proper measurement.
There are no serviceable parts on the ratio gas valve
actuator
3.10 VENTING OF GAS VALVES AND
PRESSURE SWITCHES
The optional gas pressure switches may be provided with
threaded termination points to be vented to the
atmosphere, outside the building. The gas pressure
regulation function is provided by the ratio gas valve which
does not require installation of a vent line. The optional gas
pressure switches are installed in the upper chamber of the
appliance. Threaded vent line connections from
components requiring an external vent line are provided on
the component. These vent line connection points may be
accessed by removing the top of the appliance. Local
codes may require the routing of these bleeds and vents to
the atmosphere, outside the building. Proper routing of vent
lines to the atmosphere from the factory supplied
termination points is the responsibility of the installing
contractor.
3.11

BURNER

Figure 11: Burner
This appliance uses a single cylindrical burner installed
vertically into the cavity located in the center of the primary
heat exchanger. There is a unique burner for each one of
the sixteen models.
Burners may NOT be interchanged between different Btu/hr
input models. The burner consists of a round mounting
flange welded to a mixing tube. The top side of the mixing
tube provides the transition which mounts the discharge
from the combustion air fan into the burner. The bottom
side of the mixing tube is attached to a stainless steel
perforated sleeve. This stainless steel sleeve is covered
with a knitted alloy material that forms the burner port
surface. The knitted burner port material is called metal
fiber which is a unique alloy of iron, chrome, aluminum and
several rare earth metals. This alloy is designed to operate
stress free as a burner port surface. The burner port
surface can sustain operation from a blue flame down to
infrared conditions as the burner input varies. In order to
maximize the operating life of the burner, the normal
operating mode for the DynaFlame is a blue flame. Infrared
operation will occur only if air to gas adjustments is
incorrect. If infrared operation is noted the cause must be
corrected.
The burner mounting flange provides a flame view port and
the mounting point for the hot surface igniter and the flame
sensor. The hot surface igniter and flame sensor are
removable from the burner mounting flange without
removing the burner assembly from the heat exchanger.
Never use an open flame (match, lighter, etc.) to check
gas connections.
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