The Many Benefits of Replacing Indoor Central Station Units

Modular Air Handlers

The Many Benefits of Replacing Indoor Central Station Units


For years, owners have looked at dilapidated, rusted out air handling units in their mechanical rooms and thought, “If I could only get rid of this old unit and replace it with a newer, more sophisticated design.” This is possible, provided you stop listening to the usual pitch by those who tell you to rehabilitate the old unit. After rehabilitation, you are still left with an antiquated, inefficient design and usually a very noisy unit.
Before deciding to rehabilitate, look at the possible replacement benefits:


  • New double wall 2” insulated housings versus single wall matted and torn insulation
  • Double wall sealed and latched access doors that will replace those old removable panels that are now taped onto the unit because the screws on the panel are stripped
  • Internal vibration isolation with 2” deflection springs and internally mounted motors
  • Hi-efficiency motors versus standard duty, inefficient motors
  • Variable Frequency Drives [VFD] that reduce operation expense by reducing air flow during non-peak periods
  • Energy efficient fan selection to include plenum and fan array arrangements
  • Stainless steel drain pans versus rusted out galvanized steel pans
  • Energy efficient, cleanable heating, and cooling coils that will match the actual performance of the unit today versus the arbitrary design from 30 years ago
  • Space (if available) between components for ease in monitoring and servicing
  • Low leakage dampers for mixing of outside and return air versus leaking damper sets
  • High efficiency filters with lower air velocity versus the panel inefficient furnace filters
  • Monitoring windows and lights in almost any section along with GFI outlets for servicing
  • UV light mounted downstream of cooling coil to reduce bacteria growth from the dehumidifying process


How can I remove and replace a unit in a very tight space?


Almost all units can be replaced. Very few units are in areas that would preclude a unitary changeout. USA Coil has a unit that can be shipped in modules for ease of replacement. For example: The mixing box, filter section, coil section, and fan section can each be palletized and shipped separately. These sections are easily attached at the installation site. This may be all that is required for your replacement.


On very tight projects, these modules can be taken apart in a staging area, carried into the building (and up elevators or through doors into the mechanical room) where the unit is to be installed. NOTE: Fan sections and mixing boxes that may or may not include filters might be over 33” deep and may not fit through doorways. These sections sometimes require parts breakdown and reassembly at the installation site. It is labor intensive but well worth the benefits of having a unit that will perform for the next 30+ years versus refurbishment of an old unit.


Many air handling unit replacement projects must be done primarily after hours when the space is unoccupied and that usually means weekends. We have projects where an installer has removed the old air handler on Friday, placed the new unit on Saturday, and then added new duct, pipe, and controls so the unit is ready for use on Monday morning. We also have projects where multiple units have been replaced in a facility with one unit replaced each weekend and the new unit arriving the week of the changeout.


All of this takes the professional coordination of a replacement air handler specialist and a quality installer. Key ingredients are 1) consistent communication and 2) checking each step along the way. There are many quality, service-oriented installers in your area that can easily and professionally change out your units. Why live with a less than stellar design when you can have a quieter, efficient, and more serviceable design?


NOTE:  Many units do not have the original submittals (as-builts) or even the original job schedules on building plans. No worries, USA Coil can review the physical aspects of a unit and decipher the fan, coil, and air filtering of a system without this information.  Knowing the original manufacturer and model number of the unit helps, but even that is not always required.


Many systems have had inherent operating and performance problems from the very beginning, so changing the unit is a great opportunity to alleviate those problems with the new unit design. 


Room fan coil units that are direct drive type and commercial single wall air handlers also need to be replaced. These units have all sorts of operating problems going all the way back to their original design. Often, replacing these units can include changes that overcome these inherent problems.

USA Coil