5.9 Humidification
load. Humidifiers shall be centered on the air stream
to prevent stratification of the moist air. All associated
and Water Treatment
equipment and piping shall be stainless steel.
The humidification system shall have BACnet or
LONWORKS self-contained controls.
Make-up water for direct evaporation humidifiers shall
originate directly from a potable source that has equal
Water Treatment. The water treatment for all hydronic
or better water quality with respect to both chemical
systems, including humidification systems, shall be
and microbial contaminants. Humidifiers shall be
designed by a qualified specialist. The design system shall
designed so that microbiocidal chemicals and water
address the three aspects of water treatment: biological
treatment additives are not emitted in ventilation air.
growth, dissolved solids and scaling, and corrosion
All components of humidification equipment shall be
protection. The performance of the water treatment
stainless steel. Air washer systems are not permitted
systems shall produce, as a minimum, the following
for cooling.
characteristics; hardness: 0.00; iron content: 0.00;
dissolved solids: 1,500 to 1,750 ppm; silica: 610 ppm or
Humidification shall be limited to building areas
less; and a PH of 10.5 or above. The system shall operate
requiring special conditions. Courtrooms with wall
with an injection pump transferring chemicals from
coverings of wood shall be provided with humidification.
solution tank(s) as required to maintain the conditions
General office space shall not be humidified unless
described. The chemical feed system shall have BACnet
severe winter conditions are likely to cause indoor relative
or LONWORKS self-contained controls.
humidity to fall below 30 percent.
The methods used to treat the systems' make-up water
Where humidification is necessary, atomized hot water,
shall have prior success in existing facilities on the same
clean steam or ultrasound may be used and shall be
municipal water supply and follow the guidelines
generated by electronic or steam-to-steam generators.
outlined in ASHRAE Applications Handbook.
To avoid the potential for oversaturation and
condensation at low load, the total humidification load
shall be divided between multiple, independently-
modulated units. Single-unit humidifiers are not
acceptable.
When steam is required during summer seasons for
humidification or sterilization, a separate clean steam
generator shall be provided and sized for the seasonal
140 F A C I L I T I E S S T A N D A R D S
FOR THE
PUBLIC
BUILDINGS
SERVICE
5.9 Humidification and Water Treatment
Revised March 2005 PBS-P100
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