All installations and services must be performed by qualified service personnel.
18.If the gas pressure is not within the specified high fire manifold pressure range (refer to Table 5), repeat steps 12(a) through 12(d), above, adjusting the high fire gas pressure regulator.
If the manifold pressure remains low and it cannot be adjusted into the proper range, the supply pressure may be too low. Follow these steps.
a.Turn off the gas at the manual gas shutoff valve.
b.Remove the automatic gas control valve inlet pressure tap and attach another pressure gauge to the inlet tap.
c.Turn on the gas and repeat steps 14 and 15, above.
d.Adjust the upstream (inlet) gas pressure to 14.0 in. W.G., or as close as possible.
e.Using a pressure gauge, measure and adjust the burner manifold gas pressure.
If it is still not possible increase the manifold gas pressure to within the required range, there is too little gas supply to operate the furnace at full (high fire) input rate under present conditions. If necessary, consult your gas supplier or qualified heating contractor for recommendations to alleviate the problem.
19.Turn off the gas at the manual gas shutoff valve (turn handle to the OFF position).
20.Remove all pressure gauges and replace all pressure tap plugs.
21.Go to Checkout Procedure below.
Adjusting Burner Input For Altitudes Above 2000 Feet
Ratings of gas utilization equipment are based on sea level operation and shall not be changed for operation at elevations up to 2,000 feet (600 m.). For operation at elevations above 2,000 feet (600 m), equipment ratings shall be reduced at the rate of 4 percent for each 1,000 feet (300 m) above sea level.
For additional information, refer to the latest edition of the National Fuel Gas Code.
Checking The Burner Flame
cCAUTION: The furnace model series CDX3 and CHX3 are sealed combustion designs that do not require an air shutter adjustment (air shutters are not used) for proper flame characteristics. The burner box access cover must always be secured with all screws in place and tightened before operating furnace.
Once the input rate has been confirmed correct for a specific application, the burner flames should be checked for proper adjustment.
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