Ceiling Plenum

The CP ceiling plenum conditioning package is specifically designed for pharmaceutical, electronic, and life science environmental chamber research applications. The final design incorporates any or all of the performance ranges listed:


  • Wide-range temperature control: -40°C to 85°C
  • Wide-range humidity control: 5% to 97% RH
  • Clean room particulate filtration (HEPA): Class 100 to Class 100,000
  • Explosion safe capability: Class I Div I, Class I Div II


  • Internal or external drive blower wheels
  • Multiple row evaporator coil with dehumidification coil option
  • Balanced port thermal expansion valve
  • Refrigerant distributor with hot gas side port connection
  • Rod-type resistance heat for electric defrost or elevated temperature performance

The housing and hardware of the CP unit are constructed entirely of 304 stainless steel. The components are all top quality, making our conditioning package unparalleled to others in the pharmaceutical, electronics, and life sciences fields.

The modular design facilitates a wide range of performance requirements.

We offer many options to this standard or can offer a custom unit to meet your specific needs. Please contact your local BES representative or our factory directly for more information.

Serviceability and Cleanability

  • All components are easily accessible through the latched drain pan without disturbing the surrounding ceiling grid, lights, or other ceiling mounted equipment. Access is as easy as releasing four stainless steel over-center draw latches (the drain pan can be fully removed; the pan is not hinged)


  • The housing, insulated drain pan (both interior and exterior pans) and hardware/fasteners are all constructed of 304 #3/#4 finish stainless.

This material and finish provides a high degree of corrosion resistance and an aesthetically pleasing appearance.

Cooling Components

  • Evaporator coils are either copper tubing/aluminum finish or copper tubing/copper finish. All evaporator coils include stainless steel endplates to eliminate oxidizing and other corrosive effects of moisture (rather than galvanized steel or aluminum). Special protective coatings are available upon request.


Heating Components

  • Elevated temperature chambers incorporate incoloy rod heaters with fully proportional solid state relay control (s.s.r.). This method maximizes system responses by eliminating the large thermal capacitance “lag” of tubular-finned heaters but still maintains corrosion and moisture resistance.
  • The incoloy sheath and lead wires are sealed from moisture and other contaminants via a sealed ceramic cap. The heaters are mounted on a stainless bracket and can be easily removed for cleaning or replacement.
  • All heated CP series plenums feature automatic and manual reset overtemperature thermostats. The automatic thermostat provides primary overheat protection from temperatures in excess of 200 degrees F., and the manual thermostat provides an additional safety cutout for the auto in the event of thermostat failure.

Blower Options

  • Multiple blower options are available to meet the performance requirements of the researcher and site conditions. Versions include:
    Internal motor with forward curved or backward curved wheel options for low, medium, and high flow requirements, and external motor with forward curved wheel for high flow and high static requirements. The standard forward curved wheel for external motors is constructed of spark-free aluminum, compatible with explosion safe applications.
  • Internal motors are “permanent split capacitor” (p.s.c.) or external rotor motor types for maximum efficiency and life. Standard CP series ceiling plenums do not use shaded pole motors.

Low Wall Return

  • Clean room and elevated temperature chambers include the optional low wall return. The low wall return minimizes vertical stratification by pulling return air into the conditioning plenum from floor level.
  • The low wall return is constructed entirely of 304 #3/#4 finish stainless steel. Prefilters are included at the floor intake. Standard prefilters are aluminum gross mesh roughing filters, but ES does offer other prefilter options to meet the user’s needs.