FloAire F-D Installation - Manual (Page 20)

20
Re-Circulating Control Options
The Re-Circulating system is for controlling the amount of make-up air being brought into a building. It
can be set from a minimum 20% fresh air/80% return air to a maximum of 100% fresh air/0% return air. In
order to comply with standards for recirculating direct fired heaters, different control schemes can be
chosen depending on maximum return air percentage preference, max discharge air temperature and
outside air temperature. They are shown below. If the outside air or return air falls below these minimums
the dampers will modulate to full fresh air until that respective temperature has risen above the threshold
again.
RCS
System
Minimum Outdoor
Air Temperature
(⁰F)
Minimum Indoor
Air Temperature
(⁰F)
Maximum Re-
Circulating Percentage
(%)
Maximum
Discharge
Temperature (⁰F)
RCS5 -30 7 60 90
RCS10 -30 25 50 120
RCS15 -25 58 80 90
RCS20 -25 54 60 120
RCS25 -20 55 50 140
RCS30 -15 47 60 120
RCS35 0 52 80 90
RCS40 0 35 50 140
The Re-Circulating damper motion can be controlled by four different options. With all of these options the
dampers will still modulate to full fresh air if the temperatures in the above table are not met.
Manual Positioning Control (Potentiometer)
The dampers can be controlled at a remote location by a manual potentiometer to any position from 20%
to 100% fresh air. This will allow manually setting the dampers to match the building ventilation
requirements. It will take an extra 3 control wires at the remote location. On a power failure, or if the unit is
turned off, the return air damper will close by spring return.
Two Position Control
The dampers can be controlled by a two position switch (a field supplied switching device) to open the
fresh air to 100%. On opening of the circuit, power failure, or if the unit is shutoff, the return air damper
will close by spring return.