Checking Gas Supply Pressure; Checking Differential Air And Gas Pressures - Camus Hydronics DynaFlame DFW501 Installation, Operation And Service Manual

3.6

CHECKING GAS SUPPLY PRESSURE

•
Turn the main power switch to "OFF" position.
•
Shut off gas supply at the manual gas cock in the gas
piping to the appliance. If fuel supply is LP gas, shut off
gas supply at the tank.
•
Remove the 1/8" hex plug from the gas pressure test
port located on the inlet gas supply connection at the
rear of the appliance. Install a fitting in the inlet
pressure tapping suitable to connect to a manometer
or magnahelic gauge. Range of scale should be 0 to
14 inch W.C. or greater to check inlet pressure
•
Turn on gas supply at the field installed manual gas
cock; turn on LP gas at tank if required.
•
Turn the power switch to "ON" position.
•
Adjust the thermostat set point to call for heat.
•
Observe the gas supply pressure as the burner fires at
100% of rated input.
•
Ensure inlet pressure is within specified range.
Minimum and maximum gas supply pressures are
specified in Gas Supply section of this manual.
•
If gas pressure is out of range, contact the gas utility,
gas supplier, qualified installer or service agency to
determine necessary steps to provide proper gas
pressure to the control.
•
If gas supply pressure is within normal range, proceed
to remove gas manometer and replace pressure tap
fittings in the gas piping to the appliance.
•
Turn on gas supply at the manual valve; turn on LP
gas at tank if required.
•
Turn the power switch to "ON" position.
•
Adjust the thermostat temperature set point to the
desired water temperature so the appliance will call for
heat.
•
Check appliance performance by cycling the system
while you observe burner response. The burner should
ignite promptly. Flame pattern should be stable, see
"Maintenance-Normal Flame Pattern." Turn system off
and allow burner to cool, then cycle burner again to
ensure proper ignition and flame characteristics.
IMPORTANT
Upon completion of any testing on the gas system, leak test
all gas connections with a soap solution while the main
burner is firing. Immediately repair any leak found in the
gas train or related components. DO NOT operate an
appliance with a leak in the gas train, valves or related gas
piping.
Regulated Gas Supply Pressures for DynaFlame
Boilers & Water Heaters
A stable gas supply pressure is extremely important to
avoid rough starts with machines like the DynaFlame which
use a 1 to 1 ratio control valve for internal gas pressure
regulation.
Camus requires that the DynaFlame models 3000 and
above be supplied with no more than 9" W.C. supply
pressure. This means that lockup pressure must not
exceed 9" W.C.
A suitable lockup regulator will not exceed running pressure
by more than 20% , which means that the regulator must be
capable of rated gas flow with a maximum running supply
pressure of 7.5" W.C. Running supply pressures can drop
15
to as low as 3" without affecting the appliance operation.
Each boiler needs to be installed with a final stage regulator
that is to be located as close as possible but no more than
10 feet from the appliance.
It is paramount that maximum lockup pressure be
confirmed before any attempt is made to start up the
appliance.
Operating the DynaFlame at lockup pressures exceeding 9"
W.C. is not recommended and could lead to delayed
ignitions and damage to the appliance.
3.7 CHECKING DIFFERENTIAL AIR AND GAS
PRESSURES
Figure 8 – Differential Air Pressure Manometer
Connection
•
The 1 to1 air/gas ratio control actuator has embossed
markings identifying + air – air, + gas & - gas
connections. Using a test hose assembly fitted with
tees, connections can be made from the manometer to
the appropriate ports on the actuator.
•
Using tees connect a hose from the positive air and the
negative air to each of the two sides of a manometer.
This will allow the two pressure points to be measured
while at the same time the actuator still receives the
proper operating signal.
•
If a second manometer is available it can be connected
to the appropriate gas ports. Typically the gas signal
will closely follow the air signal on all models. If the
incoming gas pressure reduces significantly as the
Variable Frequency Drive (VFD) accelerates to 60 Hz
the gas signal may lag behind the air signal by up to
15%. This will occur once the actuator has driven
downwards as far as it can go. The amount that the
actuator has opened is registered by an indictor arm
which is visible through the view window.
•
As the appliance comes on and fires, record the
maximum inches of water column which is achieved at
60 Hz on the VFD using start-up report form (93-0130).
To adjust this differential pressure, use the adjusting
screw on the air shutter to the fan. Readings are to
correspond to the values in Table 8. In all cases the
final adjustment is to be made using a combustion
analyzer. Depending on field conditions differential
pressures will have to be adjusted accordingly.
Typically with long lateral runs the differential signal as
read will be reduced from the value shown in Table 9.
The opposite will occur with tall stacks where drafts
exceed negative 0.15"W.C.