Camus Hydronics DFH/W500 Installation, Operation And Service Manual

Contents

Camus Hydronics DFH/W500 Installation, Operation And Service Manual Manual pdf 20 page image

15Figure 9: DF2000-60041:1 Air/Gas Ratio Control ValveFigure 10: DR3500 – 5000 SKP25 Regulating GasValve Actuator &SSOV3.5 DIFFERENTIAL AIR PRESSURE (DF2000 -6004)• The DynaFlame® operates on the principle of differentialpressures. Operation of the fan generates a signal whichis matched on the gas side by the 1 to 1 air/gas ratiocontrol valve.• The differential air pressure measurement is madebetween the high and low pressure taps across the fandischarge and the flue vent. All differential air pressuresare noted at full firing rate. There are two pressure taps atthe fan discharge and care must be taken to tee into thecorrect line. The correct line may be identified by tracing itback to the ratio control valve where the identification ofthe tapping is stamped into the die cast actuator.• The differential gas pressure measurement is madebetween the high and low pressure taps across the in- linemetering gas orifice. Check this value to confirm that itmatches the differential air pressure while the appliance isfiring.• The controls on this appliance may fire the burner from35% up to 100% for non-condensing and from 20% up to100 % for near-condensing and condensing of rated input.• Differential manifold gas pressure will be reduced asburner input is reduced.• All reference gas pressure measurements must be madeat 100% of rated burner input.• The differential gas manifold pressure is pre-set at thefactory through the ratio gas valve. Adjustment of manifoldpressure is not normally required for proper operation. Inthe field it may be necessary to adjust the low fireadjustment screw located on the ratio control valveactuator in order to achieve acceptable light off under softstart field conditions.• Always check settings posted on boiler test label.3.6 GAS MANIFOLD DIFFERENTIALPRESSURE ADJUSTMENT (DF2000 –DF6004)Tampering with gas valve adjustments after startup andcommissioning will void the warranty on the gas valveassembly and the burner.The appliance’s manifold gas pressure IS NOT fieldadjustable after startup and commissioning. The gas valvepressure ratios have been factory set with an internal biasadjustment to ensure a 1:1 air/gas ratio on operation.Tampering with this adjustment by a non-factory trainedtechnician will void the warranty on the gas valveassembly and the burner. An appliance supplied with aproperly sized gas line, properly sized meter and aminimum gas supply pressure (See Table 8 for minimumallowable inlet gas supply pressure) while firing at full ratewill ensure full burner input. The manifold pressuresupplied to the burner is a differential pressure. Thispressure is the result of the difference in two gas pressuremeasurements. A differential manifold gas pressuremeasurement should not be made until you havemeasured the gas supply pressure. Gas supply pressuremust be at least at minimum allowed with all appliances onthe gas line firing at full rate before a manifold pressuremeasurement is made. Use the following procedure tocheck gas supply pressure with a manometer connectedto the inlet pressure tap on the gas line connection at therear of the appliance.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 gaspiping to the appliance. If fuel supply is LP gas, shutoff gas supply at the tank.• Models 500 – 3000: Remove the 1/8" hex plug fromthe gas pressure test port located on the inlet gassupply connection at the rear of the appliance. Installa fitting in the inlet pressure tapping suitable toconnect to a manometer or magnahelic gauge. Rangeof scale should be 0 to 14 inch W.C. or greater tocheck inlet pressure• Models 3500 – 5000: Remove the 1/8” hex plugdownstream of the SKP25. Install a fitting in the inletpressure tapping suitable to connect to a manometeror magnahelic gauge. Range of scale should be 0 to14 inch W.C. or greater to check inlet pressure• Turn on gas supply at the field installed manual gascock; 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 firesat 100% of rated input.• Ensure inlet pressure is within specified range.Minimum and maximum gas supply pressures arespecified 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 todetermine necessary steps to provide proper gaspressure to the control.• If gas supply pressure is within normal range, proceedto remove gas manometer and replace pressure tapfittings in the gas piping to the appliance.• Turn on gas supply at the manual valve; turn on LPgas at tank if required.