Stimmen - 2, Durchschnittliche Bewertung: 4 ( )

Hersteller: Thomas & Betts Dateigröße: 1.08 mb Dateiname: Unterrichtssprache:

If it is determined that the blower CFM is greater than allowed or desirable, see Paragraph 14 for instructions on determining the correct size of bypass duct required. To determine temperature rise, the inlet and outlet air temperatures should be measured at points not affected by heat radiating from the heat exchanger. The following charts show the approved temperature rise range with the required CFM and the internal pressure drop for each size of unit. Model EEDU (80% thermal efficient) Size 75 100 125 140 170 200 225 250 300 350 400 Temperature Rise CFM P.D. CFM P.D. CFM P.D. CFM P.D. CFM P.D. CFM P.D. CFM P.D. CFM P.D. CFM P.D. CFM P.D. CFM P.D. 50°F 1105 0.24 1475 0.43 1840 0.49 2065 0.65 2505 0.67 2945 0.67 3315 0.69 3685 0.67 4420 0.70 5160 0.75 5895 0.77 60°F 920 0.16 1225 0.30 1535 0.33 1720 0.43 2085 0.46 2455 0.46 2765 0.47 3070 0.45 3685 0.47 4300 0.52 4915 0.52 70°F 790 0.10 1050 0.21 1315 0.25 1475 0.32 1790 0.33 2105 0.35 2370 0.36 2630 0.34 3160 0.35 3685 0.38 4210 0.38 80°F 695 0.07 920 0.16 1150 0.20 1290 0.24 1565 0.25 1840 0.26 2070 0.27 2300 0.26 2765 0.27 3225 0.28 3685 0.28 90°F 615 0.05 815 0.12 1020 0.17 1145 0.20 1390 0.19 1635 0.20 1840 0.21 2045 0.20 2455 0.22 2565 0.23 3275 0.22 Model HEEDU (80% thermal efficient, high CFM) Size 75 100 125 140 170 200 225 250 300 350 400 Temperature Rise CFM P.D. CFM P.D. CFM P.D. CFM P.D. CFM P.D. CFM P.D. CFM P.D. CFM P.D. CFM P.D. CFM P.D. CFM P.D. 20°F 2765 0.60 3685 1.09 4605 1.14 5160 1.50 6265 1.64 7370 1.64 8295 1.69 9215 1.67 11060 1.64 12900 1.64 14745 1.64 30°F 1840 0.28 2455 0.50 3070 0.52 3440 0.66 4175 0.73 4915 0.73 5530 0.75 6140 0.72 7370 0.73 8600 0.73 9830 0.73 40°F 1380 0.16 1840 0.28 2300 0.27 2580 0.36 3130 0.38 3685 0.39 4145 0.40 4605 0.40 5530 0.39 6450 0.40 7370 0.38 50°F 1105 0.12 1475 0.18 1840 0.18 2065 0.22 2505 0.24 2945 0.24 3315 0.26 3685 0.24 4420 0.24 5160 0.25 5895 0.24 60°F 920 0.10 1225 0.13 1535 0.14 1720 0.17 2085 0.17 2455 0.17 2765 0.18 3070 0.17 3685 0.17 4300 0.18 4915 0.17 65°F 850 0.08 1130 0.11 1415 0.12 1585 0.15 1925 0.14 2265 0.14 2552 0.15 2835 0.14 3400 0.14 3970 0.15 4535 0.15 70°F -- - - - - - - 1790 0.12 2105 0.12 2370 0.13 2630 0.11 3160 0.12 3685 0.13 4210 0.13 14. Constructing Bypass Duct When the CFM of air throughput is greater than desirable or permissible for the unit, a bypass duct may be constructed. Follow these instructions to determine the correct size of the bypass duct. Bypass CFM "A" Width Pressure Drop through the Furnace 0.10 0.15 0.20 0.25 0.30 0.35 0.40 0.45 0.50 3" 490 530 610 700 780 830 900 960 1010 4" 630 750 870 980 1090 1160 1250 1310 1400 5" 850 1010 1190 1300 1410 1520 1640 1730 1810 6" 1050 1290 1480 1650 1800 1940 2090 2200 2320 7" 1250 1510 1760 1960 2180 2320 2500 2650 2800 8" 1490 1810 2100 2350 2560 2760 2940 3110 3290 9" 1700 2100 2400 2700 2970 3200 3400 3600 3800 10" 1920 2350 2760 3090 3650 4020 4300 4550 4800 Directions for Sizing Bypass Duct 1) From the tables in Paragraph 13, find the pressure drop (P.D.) and the allowable CFM for the furnace that is being installed. Example: Standard Size 170 @ 70oF temperature rise; P.D. .33; CFM 1790 Figure 13 - Bypass Duct 2) Subtract the allowable CFM from the actual CFM of the installation to determine how much air must be diverted through the by pass duct. Example: Blower CFM 3000 Allowable CFM -1790 Bypass CFM 1210 3) Go to the column in the Bypass CFM Chart that is closest to the pressure drop through the heater. Move down in that column until you find the CFM closest to the answer in Step 2). Example: P.D. .35 Bypass CFM 1520 RGM Form 421, Mfg No. 150492, Page 13 14. Bypass Duct (cont'd) 4) Move to the left column to find out the required size of the bypass duct. Example: Bypass Duct Size is 5" Depth of the bypass duct is 18" on both inlet and outlet ends. Bypass duct must be located on side opposite controls and 2" from the heat exchanger side panel. NOTE: Not all capacities are covered in this chart. If your installation is not covered, the correct size may be determined by consulting the factory representative. 15. Furnace Blower Connections Requirements: Proper arrangements of blower and duct furnace with respect to angle of approach of the duct connection and the arrangement of the discharge opening of the blower are shown. Blowers should be bottom horizontal discharge when coupled to the duct furnace. When a top horizontal discharge blower is connected to the duct furnace, be sure that sufficient length of duct is provided to permit even flow of air at the end of the duct. Or, baffles may be inserted between the blower and the heater to assure an even flow of air across the heat exchanger. See illustrations in Figure 14. WARNING: The furnace must be installed on the positive pressure side of the air-circulating blower. See Hazard Levels, page 2. Form 421, Page 14 Figure 14 16. Combustion Air Proving Switch The combustion air proving switch is a pressure sensitive switch that monitors air pressure to e...

Herunterladen

Geben Sie zwei Ziffern: