Camus Hydronics Avenger Series, Installation, Operation And Service Manual

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3.5 OPERATION OF NEGATIVE PRESSURE AND DIFFERENTIAL PRESSURE VALVES
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Avenger models utilize both a negative pressure gas valve and a 1:1 air/gas ratio control valve. At the low end, these models
operate on the principle of negative pressure and at the high end they operate on the principle of differential pressure.
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The differential air pressure measurement is made between the high and low pressure taps across the fan discharge and the
fan static discharge. There are two pressure taps at the fan discharge and care must be taken to tee into the correct line. The
correct line may be identified by tracing it back to the ratio control valve where the identification of the tapping is stamped into
the die cast actuator.
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The differential gas pressure measurement is made between the high and low pressure taps across the inline metering gas
orifice. Check this value to confirm that it matches the differential air pressure while the appliance is firing.
• The controls on this appliance may fire the burner from 4.0% up to 100% of rated input.
• Differential manifold gas pressure will be reduced as burner input is reduced.
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All reference gas pressure measurements must be made at 100% of rated burner input.
• The differential gas manifold pressure is preset at the factory through the ratio gas valve. Adjustment of manifold pressure is not
normally required for proper operation. It may be necessary to adjust the low fire adjustment screw located on the ratio control
valve actuator in order to achieve acceptable light off under different field conditions.
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Always check settings posted on boiler test label (ships with the unit).
3.6 GAS MANIFOLD DIFFERENTIAL PRESSURE ADJUSTMENT
Tampering with gas valve adjustments after startup and commissioning will void the warranty on the gas valve assembly and the burner.
The appliance’s manifold gas pressure IS NOT field adjustable after startup and commissioning. The gas valve pressure ratios have been
factory set with an internal bias adjustment to ensure a 1:1 air/gas ratio on operation. Tampering with this adjustment will void the warranty
on the gas valve assembly and the burner. An appliance supplied with a properly sized gas line, properly sized meter and a minimum gas
supply pressure (see table 7 for minimum allowable inlet gas supply pressure) while firing at full rate will ensure full burner input. The
manifold pressure supplied to the burner is a differential pressure. This pressure is the result of the difference in two gas pressure
measurements. A differential manifold gas pressure measurement should not be made until you have measured the gas supply pressure.
Gas supply pressure must be at least at minimum allowed with all appliances on the gas line firing at full rate before a manifold pressure
measurement is made. Use the following procedure to check gas supply pressure with a manometer connected to the inlet pressure tap
on the gas line connection at the rear of the appliance.
3.7 CHECKING GAS SUPPLY PRESSURE
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Turn the main power to the “OFF” position.
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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.
• The boiler and its individual shutoff valve must be disconnected from the gas supply piping system during any pressure testing
of that system at test pressures in excess of ½ psi (3.5 kPa).
• The boiler must be isolated from the gas supply piping system by closing its individual manual shutoff valve during any pressure
testing of the gas supply piping system at test pressure equal to or less than ½ psi (3.5 kPa).
• 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 magnehelic gauge. Range of scale should be
0 to 14 “W.C. or greater to check inlet pressure.
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Turn on gas supply at the field installed manual gas cock; turn on LP gas at tank if required.
• Turn the power switch to the “ON” position.
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Adjust the thermostat set point to call for heat.
• Observe the gas supply pressure as the burner fires at 100% of rated input.
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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.
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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 the “ON” position.
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Adjust the thermostat temperature set point to the desired water temperature so that the appliance will call for heat.
• Check appliance performance by cycling the system while you observe burner response. The burner should ignite promptly.
Flame patterns 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.