Bard WG Series Installation Instructions Manual

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Bard WG Series Installation Instructions Manual Manual pdf 31 page image

Manual 2100-587JPage 31 of 5923. MEASURING AIR TEMPERATURERISEAir temperature rise (supply air temperature minusreturn air temperature) must be within allowable airtemperature rise range specified on furnace rating plateand in Table 1.Two thermometers with 1° resolution capable of readingup to 200° F are needed. Check thermometers tomake sure they agree, or compensate accordingly.Follow this procedure:1. Open supply air registers and return air grilles.Make sure the registers and grilles are free ofobstruction from rugs, carpets, drapes or furniture.22. CONVERSION OF GAS INPUT BTUHFROM HIGH TO LOW RATINGAll the derated WG series units are produced withmaximum BTUH input orifices installed. To fieldconvert input, a change to main burner orifices isrequired.NOTE: No change to air orifices is necessary. A setof low input orifices is shipped with everyunit. They are packaged in a bag storedbehind the burner door. Refer to the unitrating plate to confirm the proper orifice size.Proper installation of the orifices is detailed asfollows:A. Shut off electrical supply to the unit.B. Shut off gas supply to the unit.C. Remove burner access panel.D. Disconnect gas valve from gas supply piping.E. Disconnect the two wires from the gas valve.F. Remove manifold assembly to make orificesaccessible and remove orifices.G. Apply a modest amount of pipe compound to thenew orifices and screw them into the manifold.H. To assemble burner reverse steps A through G.2. Set balancing dampers in supply duct system.3. Check duct work for obstructions or leaks.4. Make sure filters are clean and in place.5. Place one thermometer in supply air plenumapproximately 2' from furnace. Locatethermometer tip in center of plenum to ensureproper temperature measurement.6. Place second thermometer in return airduct approximately 2' from furnace. Locatethermometer tip in center of duct to ensureproper temperature measurement.7. Set room thermostat on highest temperaturesetting. Operate furnace 10 minutes. Recordsupply air and return air temperatures.8. Calculate air temperature rise by subtractingreturn air temperature from supply airtemperature.• If air temperature rise is above thetemperature rise range on rating plate, furnaceis overfired or has insufficient airflow. Checkgas input following the instructions found insection “Checking Gas Input Rate”. If airtemperature rise is still above temperaturerise range specified, more heating airflow isneeded. Check duct work and grilles to makesure all are properly sized.• If air temperature rise is below thetemperature rise range on rating plate, furnaceis underfired or has too much airflow. Checkgas input following the instructions found insection “Checking Gas Input Rate”. If airtemperature rise is still below temperature riserange specified, less heating airflow is needed.Adjust dampers or grilles as needed.• After making adjustments, check airtemperature rise to verify that resulting airtemperature rise is within allowable range.If air temperature rise is still outside thetemperature rise range specified on ratingplate, check duct system design with aqualified heating engineer. It may benecessary to re-size the duct work. Recheckair temperature rise after revising ductsystems.9. Set room thermostat to desired setting.10. Remove thermometers and seal duct work holes.NOTE: Failure to seal holes could result in reducedsystem performance.WARNINGFailure to follow these instructions could createa hazard resulting in property damage, bodilyinjury, or death.