Nortec NHTC - Manual (Page 48)

10-10
Page 40
2008-10-01
CAUTION
UNLESS YOU KNOW THE EXACT ABORPTION DISTANCE
REQUIRED FOR THE STEAM ABSORPTION INTO THE AIR STREAM,
THE DISTRIBUTOR SHOULD BE LOCATED AT LEAST 8-10 FT (2-3 M)
AWAY FROM ANY OBSTACLE IT MAY CONDENSE ON (ELBOW,
DIFFUSER, FILTER, ETC.)
(2) Duct vertical clearance requirements for standard steam distributors are as follows:
(a) ASD - 8 in. vertical duct height for 1st ASD
- 5.5 in. additional duct height for each additional ASD
= ROUNDDOWN (‘DuctHeight’ - 8")/5.5) + 1
(b) BSD - 10 in. vertical duct height for 1st BSD
- 6.375 in. additional duct height for each additional BSD
= ROUNDDOWN (‘DuctHeight’ - 10")/6.375) + 1
(c) CDS - 14 in. vertical duct height for 1st CSD
- 9 in. additional duct height for each additional CSD
= ROUNDDOWN (‘DuctHeight’ - 14")/9) + 1
NOTE
These requirements apply to vertical arrangements of multiple distributors ONLY.
Diagonal arrangements utilize an alternative method.
E. LOCATION OF STEAM DISTRIBUTORS WITHIN AN AIR HANDLER
(1) Humidify after the heating
coil (H/C) so that absorption will
occur in the 3 to 4 feet before the
cooling coil (C/C). If steam carries
over and condenses on the coil,
any excess water will be drained
away. There is little chance of
condensation on the blower,
blower motor, or fan isolation
components, especially if you use
a modulating high limit humidistat.
All steam distributors should be 8"
from the H/C and evenly spaced. If
wetting is a problem, add more
steam distributors. (See
Nomogram Figure 13 and
Figure 14).
F. DISTRIBUTOR ABSORPTION
DISTANCE
(1) The water vapor discharged from
the steam distributor must be
adequately mixed with air to
prevent condensation on
downstream components. The
nomogram in figure 13 will
Figure 14. Best Location for Multiple Steam
Distributors in AHU