JOHNSON CONTROLS
15
FORM 102.20-N1 
ISSUE DATE: 7/06/2016
2
SECTION 2 - PRODUCT DESCRIPTION
Ventilation System
The purpose of a ventilation system is to remove air 
that is substandard to creature comfort or a process, 
and replace it with suitable air. Depending on the ap-
plication, the system will operate at various specified 
rates, volumes, and conditions. A ventilation system 
may employ an AHU with a supply fan working in 
conjunction with a remote exhaust fan(s). A more ef-
fective method would employ a supply fan and an ex-
haust fan in the AHU.
Economizer System (Typical)
The economizer system typically consists of:
• Outdoor and return air dampers
• Damper actuator
• Enthalpy control
• Minimum outdoor air adjustment
• Exhaust air control
The economizer system provides the first stage of cool-
ing whenever the outdoor air is cool and dry enough to 
satisfy the internal cooling demand. The outdoor and 
the return air dampers are operated by individual ac-
tuators. As the outdoor air dampers are opened by the 
damper actuator, the return air dampers are closed.
The AHU features segmented construction, and is fac-
tory assembled. Segment arrangements will vary to suit 
the job application as shown in Figure 1 on page 15. 
Features of the AHU include:
• Heavy gauge galvanized steel is used on the exte-
rior and interior of the AHU. 
• Access doors are provided for accessibility to the 
various sections. 
• Removable access panels are standard in lieu of 
doors on commercial performance AHUs. 
• Panels and doors are constructed with double 
walls. 
• Panels, doors, and structural frame are insulated 
with spray-injected foam.
TYPICAL SOLUTION OPERATION
The operation of the AHU is divided into four systems:
1.  Ventilation
2.  Economizer (Return Air/Mixing Box Section)
3.  Heating
4.  Cooling
5.  Cleaning
LD13764
FIGURE 1 - CUTAWAY OF SOLUTION XT
 
SHOWING SEGMENTED CONSTRUCTION