Sterling RT User Manual
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BYPASS SIZING INFORMATION
(BUILT ON THE JOB – NOT FURNISHED BY
FACTORY)
On occassion when a duct furnace is incorporated in an
air handling system, it may be desirable to handle a total
of more CFM than the duct furnace will pass at a given
static pressure drop and temperature rise. Therefore, it
is necessary to arrange to bypass the additional CFM
required. The size of the bypass duct can be determined
by referring to the chart. This permits the static pressure
drop through the bypass to balance off the drop through
the heat exchanger. The bypass duct is not factory
furnished and must be built on the job by the installer and
a damper placed therin if required.
USE OF BYPASS CURVES
The width of the by-pass for CFM in excess of that
provided through the heater may be found in the
following manner:
1. Determine the CFM and pressure drop through
the heater based on the heating requirement
specifi cations.
2. Determine the additional CFM desired, over and
above the CFM for the heating requirements.
3. Using the pressure drop which was determined from
performance curves above, for the heating load,
locate this pressure drop on the by-pass curves.
Follow this curve until it intersects the vertical CFM
line for the excess CFM desired.
4. Follow horizontal line to left to obtain width of by-pass
duct.
Figure 5 - By-Pass Curve