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Paul S_3
Paul S_3 Member Posts: 1,257
On a downflow application with a warm air furnace and a standard evaporator coil. .... Where should the coil be placed on the supply? Can it be installed on the return? If not why.... Thanks Paul S
ASM Mechanical Company
Located in Staten Island NY
Servicing all 5 boroughs of NYC.
[email protected]


  • Spence
    Spence Member Posts: 316
    edited February 2014
    The Evaporator

    Delivering comfort and economy is all about pressure, and how to manipulate it to your advantage. In the purest sense, the outlet of the blower is the highest pressure while the inlet is the lowest. Evaporator coils can easily be the system component with the highest PD, so you want to account for it where you have the most with which to work (blower outlet). The heat exchanger's PD is included in the blower selected by the manufacturer.

    With this in mind, the furnace would have to be raised to get the coil directly underneath, and there are coils and accessory plates expressly for this purpose. Some have left the furnace in place and put the coil in the crawl (a horrible idea). Watch your RA though; raising the furnace for the coil can make changing filters a PIA.