Quick Reference Guide

10 UNT-PRC015-EN
Riser Connections
Each branch run-out in the coil section must be centered in the expansion slot on the side or back
panel before joining risers. Risers are coupled/connected together with a swaged connection. (A
swage connection might be referred to as a ”bell” connection also.) The swage or bell is the
expanded portion of the riser pipe where an adjoining pipe of nominal diameter is inserted. A riser
can be swaged on the top or bottom.
Important: The type of connection on the top and bottom of the riser must be specified
and configured correctly. Field remedy of these errors is costly!
The adjoining unit’s riser is inserted into the swage joint and brazed together. Riser joints must be
made with phos-copper, silfos, or other high temperature alloys. Soft solders (50-50, 60-40 and
85-15) or other low temperature lead alloys are NOT suitable for this application. It is important to
configure the upper and lower end of each unit’s riser to accommodate the upper and lower
adjoining unit riser. Pay particular attention to the riser design in a reverse return system where the
larger diameter riser may be at the top of the riser column. Job site coordination is critical to avoid
costly error correction.
The length of the swage joint is 3 inches. This length allows some tolerance to account for
miscalculations in riser length or tolerance of building structures and floor-to-floor distances. Each
riser joint must be vertically aligned, with a minimum of one-inch penetration (although two inches
is preferable and allowed for), into each swaged joint. This condition will be met if floor-to-floor
dimensions are as specified and each branch run is properly centered. Wide variations in floor-to-
floor dimensions may necessitate cutting off or extending individual risers.
A capped connection is installed on the top or bottom when there are no more adjoining riser
connections.
Swage connections are not available on risers made with type K copper pipe. Separate couplings
and bell reducers must be used.
Figure 6.