Nortec NHTC User Manual download pdf (Page 27)

10-10

Page 19

2008-10-01

(3) Using the natural ventilation method requires knowing the volume of the humidified

space and the type of construction. A tightly constructed building will have a least one

air change per hour. A loosely constructed building will have at least one and one half

changes per hour, and this same building with a large a amount of incoming or exiting

traffic will have at least two air changes per hour.

(a) Formula 3

Assume our print shop has a floor area of 100'

x 100' with a 20' ceiling with a

large amount of traffic. This requires

100' x 100' x 20' x 2 = 400,000 ft

/hr.

Using our example, the moisture required is

400,000 x 5.08

_______________

= 290 lbs/hr

7000 grains/lb

(4) Using make-up air:

(a) Formula 4

Assume our print shop has a 15,000 CFM HVAC system and uses 10%

make-up air during winter. The amount of outside make-up air entering the

HVAC system will, therefore, be 10% of 15,000 CFM = 1,500 CFM. The

moisture required will be

1,500 x 5.08 x 60 min/hr

_________________________

= 65 lbs/hr

7,000 grains/lb

(Refer to Figure 1.)

Figure 1. Schematic of a Typical Print Shop HVAC System

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Nortec NHTC User Manual Page 27