Humidity control with
rooftop systems
Air quality, conditioning, recycled energy, humidity solutions
Drier buildings through
atmosphere conditioning
A hot gas reheat system in
essence “wrings” moisture from
the air, providing occupants a
more comfortable environment
to learn, work, rehabilitate or
play. For the building owner, it
means decreased maintenance
expense due to damage caused
by interior moisture.
Drier buildings simply feel better. Humidity-
control helps to preserve building structures
managed facilities offer a greater sense
and furnishings by reducing moisture-based
of comfort, and a healthier environment.
contaminants that have the potential to
Dehumidification is an on-going process of
cause damage.
reducing or removing excess moisture from
Buildings that
benefit from
humidity control:
• Retail outlets
• Restaurants
• Schools
• Warehouses
• Recreation facilities
• And other
climate controlled
spaces . . .
the air. Controlled humidity improves comfort,
Climate conditioning
reduces moisture-based contaminant growth,
While dehumidifying a building does not reduce
and preserves building interiors.
temperature, it makes the air “feel” warmer.
Keeping indoor humidity at acceptable levels:
Indoor Air Quality (IAQ)
The air we breathe is an especially important
consideration when choosing a mechanical
system. Properly conditioned indoor air goes
• Greatly improves comfort
• Decreases occupant complaints
• Increases market values of facilities
beyond quality—it encompasses the health and
The American Society of Heating, Refrigeration
safety of facility occupants.
and Air Conditioning Engineers (ASHRAE) has
Humidity control provides a positive means to
increase a building’s IAQ, while decreasing health
issues and absenteeism. In addition, humidity
developed Standard 62-2001, Ventilation for
Acceptable Indoor Air Quality. It addresses indoor
moisture and microbial growth by recommending:
Moisture control
an outside ventilation system, human respiration,
One of the key steps to creating an interior
cooking, wet cleaning, or infiltration through
environment that offers a comfortable
cracks and other exterior openings.
atmosphere for learning, working, rehabilitation
and recreational activities is to understand how
Moisture removal
moisture enters a building.
Regardless of how moisture enters a building,
Moisture enters a building in either a liquid
or vapor state. Leaky roofs and damp carpets,
condensation on cold surfaces, or leaky pipes
it has the potential to cause disruption, illness
and damage. Removing unwanted moisture will
significantly enhance any interior environment.
can all contribute to liquid moisture. In a vapor
state, moisture may enter the building through
“Relative humidity in habitable spaces preferably should be
maintained between 30 percent and 60 percent to minimize the
growth of allergenic pathogenic organisms.” (Section 5.10)
Recycled energy . . .
A humidity control solution!
Trane’s hot gas reheat dehumidification system
can help facility designers and operators keep
their buildings in their “comfort zone.” With a
single unit, the system senses and controls both
space humidity and temperature independently.
The system operates conventionally when there is
a demand for cooling without dehumidification,
but on those humid days, the hot gas reheat
system will remove unwanted moisture from the
air. The result: both temperature and humidity
are maintained without the wasteful and costly
use of new energy.
Mixed Supply/Return Air
The hot gas reheat
system recycles
energy that would
otherwise be wasted.
Dehumidification
allows for and
improved indoor
air quality.
Condenser
Coil
Evaporator Coil
used to
dehumidify air
Thermal
Expansion
Valve
Reheat Coil
used to
neutralize air
Compressor
Reheat
Valve
Trane optimizes the performance of homes and buildings around the world. A business of Ingersoll Rand, the leader in creating and sustaining safe, comfortable
and energy efficient environments, Trane offers a broad portfolio of advanced controls and HVAC systems, comprehensive building services, and parts.
For more information, visit www.Trane.com.
© 2009 Trane All rights reserved
RT-SLB006-EN November 23, 2009
Produced on 20% post-consumer recycled paper, using
environmentally friendly print practices that reduce waste.