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1.6 CONDENSATION & DRAINAGE
Condensation is formed in the piping of a mitigation system when the air in the piping is chilled
below its dew point. This can occur at points where the system piping goes through unheated
space such as an attic, garage or outside. The system design must provide a means for water to
drain back to a slab hole to remove the condensation. The GP/XP/XR Series Fan MUST be
mounted vertically plumb and level, with the outlet pointing up for proper drainage through the
fan. Avoid mounting the fan in any orientation that will allow water to accumulate inside the fan
housing. The GP/XP/XR Series Fans are NOT suitable for underground burial.
For GP/XP/XR Series Fan piping, the following table provides the minimum recommended pipe
diameter and pitch under several system conditions.
Pipe
Dia.
@25 CFM
4"
1/8"
3"
1/4"
*
Typical GP/XP/XR Series Fan operational flow rate is 25 - 90 CFM.
(For more precision, determine flow rate by using
the chart in the addendum.)
Under some circumstances in an outdoor installation
a condensate bypass should be installed in the outlet
ducting as shown. This may be particularly true in
cold climate installations which require long lengths
of outlet ducting or where the outlet ducting is likely
to produce large amounts of condensation because of
high soil moisture or outlet duct material. Schedule
20 piping and other thin-walled plastic ducting and
Aluminum downspout will normally produce much
more condensation than Schedule 40 piping.
The bypass is constructed with a 45 degree Wye
fitting at the bottom of the outlet stack. The bottom of
the Wye is capped and fitted with a tube that
connects to the inlet piping or other drain. The
condensation produced in the outlet stack is collected
in the Wye fitting and drained through the bypass
tube. The bypass tubing may be insulated to prevent
freezing.
1.7 "SYSTEM ON" INDICATOR
A properly designed system should incorporate a
"System On" Indicator for affirmation of system
operation. A manometer, such as a U-Tube, or a
vacuum alarm is recommended for this purpose.
Page 3 of 8
Minimum Rise per Foot of Run*
@50 CFM
1/4"
3/8"
@100 CFM
3/8"
1 1/2"
RISE
RUN
IN014 Rev I
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