Subject to change without notice. Printed in U.S.A. 278432-YTG-A-0407Copyright © by York International Corp. 2007. All rights reserved. Supersedes: 246768-YTG-B-0706Unitary 5005 NormanProducts York OKGroup Drive 73069APPLYING FILTER PRESSURE DROP TODETERMINE SYSTEM AIRFLOWTo determine the approximate airflow of the unit with a filter inplace, follow the steps below:1. Select the filter type.2. Select the number of return air openings or calculate thereturn opening size in square inches to determine theproper filter pressure drop.3. Determine the External System Static Pressure (ESP)without the filter.4. Select a filter pressure drop from the table based uponthe number of return air openings or return air openingsize and add to the ESP from Step 3 to determine thetotal system static.5. If total system static matches a ESP value in the airflowtable (i.e. 0.20 w.c. (50 Pa), 0.60 w.c. (150 Pa), etc,) thesystem airflow corresponds to the intersection of theESP column and Model/Blower Speed row.6. If the total system static falls between ESP values in thetable (i.e. 0.58 w.c. (144 Pa), 0.75 w.c. (187 Pa), etc.),the static pressure may be rounded to the nearest valuein the table determining the airflow using Step 5 or calcu-late the airflow by using the following example.Example: For a 60,000 BTUH (17.58 kW) furnace with a bot-tom return opening and operating on high-speed blower, it isfound that total system static is 0.58” w.c. To determine thesystem airflow, complete the following steps:Obtain the airflow values at 0.50 w.c. (125 Pa) & 0.60 w.c.(150 Pa) ESP.Airflow @ 0.50”: 1250 CFM (35.4 m 3 /min)Airflow @ 0.60”: 1180 CFM (33.4 m 3/min)Subtract the airflow @ 0.50 w.c. (125 Pa) from the airflow @0.60 w.c. (150 Pa) to obtain airflow difference.1180 - 1250 = -70 CFM (-12 m 3 /min)Subtract the total system static from 0.50 w.c. (125 Pa) anddivide this difference by the difference in ESP values in thetable, 0.60 w.c. (150 Pa) - 0.50 w.c. (125 Pa), to obtain apercentage.(0.58 - 0.50) / (0.60 - 0.50) = 0.8Multiply percentage by airflow difference to obtain airflowreduction.(0.8) X (-70) = -56Subtract airflow reduction value to airflow @ 0.50 w.c. (125Pa) to obtain actual airflow @ 0.58 in. w.c. (144 Pa) ESP.1250 - 56 = 1194ACCESSORIESPROPANE (LP) CONVERSION KIT -1NP0347 - All ModelsThis accessory conversion kit may be used to convert naturalgas (N) units for propane (LP) operation. Conversions mustbe made by qualified distributor or dealer personnel.SIDE RETURN FILTER -1SR0302 - All Models1SR0200 - All ModelsBOTTOM RETURN FILTER -1BR0114 or 1BR0214 - For 14-1/2” cabinets1BR0117 or 1BR0217 - For 17-1/2” cabinets1BR0121 or 1BR0221 - For 21” cabinets1BR0124 or 1BR0224 - For 24-1/2” cabinetsINTERNAL FILTER WITH FIBER FILTER -1HF0801 - All ModelsHIGH ALTITUDE PRESSURE SWITCHES -For installation where the altitude is less than 8,000 feet it isnot required that the pressure switch be changed. For alti-tudes above 8,000 feet see kits below. Conversion must bemade by qualified distributor or dealer personnel.1PS0301 - 040, 060 MBH1PS0302 - 080 MBH1PS0311 - 100, 115, 130 MBHROOM THERMOSTATS - A wide selection of compatiblethermosets are available to provide optimum performanceand features for any installation.1H/1C, manual change-over electronic non-programmablethermostat.1H/1C, auto/manual changeover, electronic programmable,deluxe 7-day, thermostat.1H/1C, auto/manual changeover, electronic programmable.* For the most current accessory information, refer to theprice book or consult factory.