Nortec NHPC 10-10, F.Distributor Absorption Distance, Best Location for Multiple Steam, Page 40

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

10-10

Page 40 2008-10-01