Camus Hydronics DRH300, Installation, Operation And Service Manual

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3.7 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.
•
Models 300 – 3000: 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
•
Models 3500 – 5000: Remove the 1/8” hex plug
downstream of the SKP25. 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 Table
7.
•
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.
3.7.1 Regulated Gas Supply Pressures for Dynaforce®
Boilers & Water Heaters
A stable gas supply pressure is important to avoid rough starts
with machines like the Dynaforce® which use a 1 to 1 ratio
control valve for internal gas pressure regulation.
Camus® requires that all Dynaforce® models equipped with
the SKP25 be supplied with no more than 1 PSI incoming
supply pressure. This means that lockup pressure must not
exceed 1 PSI. For models NOT incorporating the SKP25,
lockup pressure must not be in excess of 14” w.c.
A suitable lockup regulator with internal or external relief will
not exceed running pressure by more than 20%.
When required a final stage gas regulator 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 Dynaforce® at lockup pressures exceeding
the recommended levels can lead to delayed ignitions and
damage to the appliance.
3.8 CHECKING DIFFERENTIAL AIR AND
GAS PRESSURES (DR2000 – DR5000)
Figure 12: Checking Differential Air and Gas Pressures
(DR2000 – DR5000)
•
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 VFD accelerates to maximum
speed 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
indicator 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 maximum speed on the VFD using start-up report
form (93-0130). To adjust this differential pressure
when commissioning the appliance, use the adjusting
screw on the air shutter to the fan. 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 on the
Fan Inlet
Firing
Valve
Metering
Valve
Differential High
Gas Switch
Control Valve
Regulator Valve
Main Manual
Valve
Low Gas Switch
To Fan Discharge
To
Appliance
Vent