FloAire INDIRECT FIRED BENT TUBE MODULE - Manual (Page 5)

5
Recommended Supply Ductwork Sizes
Blower Size Duct Size Straight Duct Length
10 14 x 14 48 in.
12 16 x 16 54 in.
15 20 x 20 72 in.
18 24 x 24 86 in.
20 26 x 26 108 in.
25 32 x 32 168 in.
and square elbows should not be used. Also,
transitions and turns in ductwork near the fan
outlet will cause system effect and will drastically
increase the static pressure and reduce airflow.
The chart below shows the minimum fan outlet
duct sizes and straight lengths recommended for
optimal fan performance. Follow SMACNA
guides
and recommendations for the
remaining duct run. Fans designed for rooftop
installation
should be installed on a
prefabricated or factory built roof curb. Follow
curb manufacturer’s instructions for proper curb installation. The unit should be installed on a curb and/or
rail elevated not less than 20” above any surface. Be sure duct connection and fan outlet are properly
aligned and sealed. Secure fan to curb through vertical portion of the ventilator base assembly flange
using a minimum of eight (8) lug screws, anchor bolts, or other suitable fasteners (not furnished). Shims
may be required depending upon curb installation and roofing material. Check all fasteners for tightness.
The diagrams below show different mechanical installation configurations.
Condensation Drain
In some applications, condensation can form in the flue collection box, especially when furnaces are
located downstream of cooling coils. In the event that condensation occurs in the flue collection boxes,
there are barbed fittings in the bottom of the flue collection boxes to drain condensation out of the boxes.
Each burner in the unit is provided with a burner drain pan or a condensation drain assembly located
underneath this fitting for the condensation to collect. If the drain assembly is installed on the heater, it will
have ¼” quick seals located below the front access door for field piping or drainage onto the roof. Consult
your local code as to the proper drainage regulations of the condensation. The internal drain piping is
heated to prevent freezing. If drains are field piped, ensure that the field piping is piped in a fashion to
prevent the condensation from freezing. Do not plug the holes under any circumstance as it will cause the
burners to overflow.
In the event the IBT does not have condensation drains and condensation exceeds the pan capacity, IBT
condensation drain kits can be ordered for installation in the field.
The part names for the kits are:
“IBT Condensation Kit-1” Single Furnace IBT
“IBT Condensation Kit-2” Double Furnace IBT
“IBT Condensation Kit-3” Triple Furnace IBT
“IBT Condensation Kit-4” Quadruple Furnace IBT
IBT Condensation Drain Assembly ¼” NPT Condensation Drain Connections