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The inlet is always at the bottom of the coil and the outlet is always at the top of the coil. All
coils are piped so that the inlet is always on the row farthest downstream from the incoming air
(See diagram 1).
All coils have one or more circuits. Circuits are added to reduce the water pressure drop to an
acceptable level (usually 10-ft. H²O pressure drop or less). Due to the various circuit options
available, the inlet, and outlet may change position making the inlet and outlet locations vary.
Four-Pipe Coils
Four-pipe coils have a dedicated, chilled-water coil, and a dedicated hot-water coil, each with its’
own inlet and outlet, equaling four pipes. All coils have a common tube sheet for four-pipe coils.
Example: A four-row, chilled-water coil and a one-row, hot-water coil would use a five-row coil
with four rows for chilled-water and one row for hot-water. Normally the one-row, hot-water coil
is in the reheat position or downstream from the cooling coil. The hot-water coil may also be
ordered in the preheat position or upstream from the chilled-water coil. The controls are wired so
that either the chilled-water coil is operating or the hot-water coil is operating, but not both at the
same time. When the conditioned space thermostat is satisfied, both the chilled- and hot-water
control valves are deactivated. The same rule applies for inlet and outlet locations as explained
above in “Two-Pipe Coils” (See diagram 2). Each chilled- and hot-water coil is controlled
individually so a pipe sensor is not required.
Hose Kits
When hose kits are being used on units it is important to make sure the hoses are not installed
over any electrical components, such as j-boxes, actuators, etc. Hoses are not sweat proof so
they can condensate. It is recommended that the flex hoses be field insulated during installation.
Failure to follow these directions may cause unit operation failure.
Coil Identification
The following diagrams indicate the number of rows and type of chilled- and hot-water coils.
Standard coil has the hot-water coil located in the reheat position.
Because of the variations of circuiting available, the location of the inlet and outlet connections
may vary up and down. However, always use the following rule to be correct.
The inlet is
always the lower connection and the farthest away from the entering-air-side. The outlet
connection is always the higher connection closest to the entering-air-side.
