Bard W24G2-A Installation Instructions Manual

Bard W24G2-A Installation Instructions Manual Manual pdf 32 page image

Manual 2100-590APage 32 of 6723. MEASURING AIR TEMPERATURERISEAir temperature rise (supply air temperature minusreturn air temperature) must be within allowable airtemperature rise range specified on furnace rating plate.You will need 2 thermometers with 1 degree resolutioncapable of reading up to 200 degrees F. Checkthermometers to make sure they agree, or compensateaccordingly.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 will be found packaged in a bagbehind the burner door. Refer to the unitrating plate to confirm the proper orifice size.Proper installation of the orifices is detailedas follows: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 the manifold assembly so that orifices arenow accessible 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 feet from furnace. Locatethermometer tip in center of plenum to insure propertemperature measurement.6. Place second thermometer in return air ductapproximately 2 feet from furnace. Locatethermometer tip in center of duct to insure propertemperature measurement.7. Set room thermostat on highest temperature setting.Operate furnace 10 minutes. Record supply air andreturn air temperatures.8. Calculate air temperature rise by subtracting returnair temperature from supply air temperature.• If air temperature rise is above the temperaturerise range on rating plate, furnace is overfiredor has insufficient airflow. Check gas inputfollowing the instructions in Section, “CheckingGas Input Rate”. If air temperature rise is stillabove temperature rise range specified, moreheating airflow is needed. Check duct work andgrilles to make sure all are properly sized.• If air temperature rise is below the temperaturerise range on rating plate, furnace is underfiredor has too much airflow. Check gas inputfollowing the instructions in Section, “CheckingGas Input Rate”. If air temperature rise is stillbelow temperature rise range specified, lessheating airflow is needed. Adjust dampers orgrilles as needed.• After making adjustments, you must check airtemperature rise to verify that resulting airtemperature rise is within allowable range. Ifair 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 duct systems.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 couldcreate a hazard resulting in property damage,bodily injury, or death.