Selecting Return Lines
Selecting return pipes that are one or two sizes larger than the require minimum size means:
- Increased plant activity.
- Preventing the failure of one trap from impeding the others.
- Traps especially prone to problems caused by back pressure enjoy sufficient operating latitude.
Larger pipes also reduce problems with:
- Eventual fouling of one pipe by rust or scale.
- Unexpected rises in condensate load.
The following tables are expressed as imperial values. To view these tables in SI metric units, click here.
Flow Rate (lbs/hr) for Dry-Closed Return
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a = For these sizes and pressure losses the velocity is above 7,000 fpm. Select another combination of size and pressure loss. Chart reprinted with permission from ASHRAE Handbook - 1985 Fundamentals. |
