York DM036 Installation Manual

Also see for DM 036: Technical guide

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York DM036 Installation Manual Manual pdf 43 page image

5011492-XIM-B-0815Johnson Controls Unitary Products 43consumed per hour from the Gas Rate - Cubic Feet PerHour (Table 27).If the actual input is not within 5% of the furnace rating (withallowance being made for the permissible range of the regulatorsetting), replace the orifice spuds with spuds of the proper size.NOTE: To find the Btu input, multiply the number of cubic feetof gas consumed per hour by the Btu content of the gasin your particular locality (contact your gas company forthis information - it varies widely from city to city.)Adjustment Of Temperature RiseThe temperature rise (or temperature difference between thereturn air and the heated air from the furnace) must lie withinthe range shown on the rating plate and the data in the GasHeat Application Table 3.After the temperature rise has been determined, the VolumetricFlow Rate can be calculated as follows:After about 20 minutes of operation, determine the furnacetemperature rise. Take readings of both the return air and theheated air in the ducts (about six feet from the furnace) wherethey will not be affected by radiant heat. Increase the blowerVolumetric Flow Rate to decrease the temperature rise;decrease the blower Volumetric Flow Rate to increase the rise.Refer to the Blower Motor and Drive Data Table 21.Table 27: Gas Rate - Cubic Feet Per Hour 1Seconds for onerev.Size of Test Dial1/2 cu. ft. 1 cu. ft.10 180 36012 150 30014 129 25716 113 22518 100 20020 90 18022 82 16424 75 15026 69 13828 64 12930 60 12032 56 11334 53 10636 50 10038 47 9540 45 9042 43 8644 41 8246 39 7848 37 7550 36 7252 35 6954 34 6756 32 6458 31 6260 30 601. By actual measurement, it takes 38 seconds for the hand onthe 1-cubic foot dial to make a revolution with a 100,000 Btuhfurnace running. Using this information, located 38 secondsin the first column in the table above. Read across to the col-umn headed “1 Cubic Foot”, where you will see that 95 cubicfeet of gas per hour are consumed by the furnace at that rate.Multiply 95 X 1050 (the Btu rating of the gas obtained fromthe local gas company). The result is 99,750 Btuh, which isclose to the 100,000 Btuh rating of the furnace.Table 27: Gas Rate - Cubic Feet Per Hour1Seconds for onerev.Size of Test Dial1/2 cu. ft. 1 cu. ft.CFM Btuh Input x 0.8= 108. .x F Temp Riseo