York LY8S warranty Applying Filter Pressure Drop to Determine System Airflow, Accessories

APPLYING FILTER PRESSURE DROP TO DETERMINE SYSTEM AIRFLOW

To determine the approximate airflow of the unit with a filter in place, follow the steps below:

1.Select the filter type.

2.Select the number of return air openings or calculate the return opening size in square inches to determine the proper filter pressure drop.

3.Determine the External System Static Pressure (ESP) without the filter.

4.Select a filter pressure drop from the table based upon the number of return air openings or return air opening size and add to the ESP from Step 3 to determine the total system static.

5.If total system static matches a ESP value in the airflow table (i.e. 0.20 w.c. (50 Pa), 0.60 w.c. (150 Pa), etc,) the system airflow corresponds to the intersection of the ESP column and Model/Blower Speed row.

6.If the total system static falls between ESP values in the table (i.e. 0.58 w.c. (144 Pa), 0.75 w.c. (187 Pa), etc.), the static pressure may be rounded to the nearest value in 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 is found that total system static is 0.58” w.c. To determine the system 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 m3/min)

Airflow @ 0.60”: 1180 CFM (33.4 m3/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 m3/min)

Subtract the total system static from 0.50 w.c. (125 Pa) and divide this difference by the difference in ESP values in the

table, 0.60 w.c.	(150 Pa) - 0.50 w.c. (125 Pa), to obtain a
percentage.

(0.58 - 0.50) / (0.60 - 0.50) = 0.8

Multiply percentage by airflow difference to obtain airflow reduction.

(0.8) X (-70) = -56

Subtract airflow reduction value to airflow @ 0.50 w.c. (125 Pa) to obtain actual airflow @ 0.58 in. w.c. (144 Pa) ESP.

1250 - 56 = 1194

ACCESSORIES

PROPANE (LP) CONVERSION KIT -

1NP0347 - 040, 080,100 MBH

1NP0348 - 060, 115, 130 MBH

This accessory conversion kit may be used to convert natural gas (N) units for propane (LP) operation. Conversions must be made by qualified distributor or dealer personnel.

SIDE RETURN FILTER -

1SR0302 - All Models

1SR0200 - All Models

BOTTOM RETURN FILTER -

1BR0114 or 1BR0214 - For 14-1/2” cabinets 1BR0117 or 1BR0217 - For 17-1/2” cabinets 1BR0121 or 1BR0221 - For 21” cabinets 1BR0124 or 1BR0224 - For 24-1/2” cabinets

INTERNAL FILTER WITH FIBER FILTER -

1HF0801 - All Models

HIGH ALTITUDE PRESSURE SWITCHES -

For installation where the altitude is less than 8,000 feet it is not required that the pressure switch be changed. For alti- tudes above 8,000 feet see kits below. Conversion must be made by qualified distributor or dealer personnel.

1PS0301 - 040, 060 MBH 1PS0302 - 080 MBH 1PS0311 - 100, 115, 130 MBH

ROOM THERMOSTATS - A wide selection of compatible thermosets are available to provide optimum performance and features for any installation.

1H/1C, manual change-over electronic non-programmable thermostat.

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 the price book or consult factory.

Subject to change without notice. Printed in U.S.A.	036-21618-003	Rev. A (1205)
Copyright © by Unitary Products Group 2005. All rights reserved.	Supersedes: 036-21618-002	Rev. A (1004)

Unitary	5005	Norman
Products	York	OK
Group	Drive	73069