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MODU-FIRE® FORCED DRAFT
Gas-Fired Boiler Installation
3.8.2 Boiler Water Connections
Boiler Water Connections
Make water connections as the application warrants,
or at a minimum, as shown, but always in compli-
ance with the local requirements.
Notice: Pipe unions and isolating valves must be
installed in both water connections for ease of
service.
The bottom connection to the boiler is the INLET
and must be used for the return from the system.
The top connection to the boiler is the OUTLET and
must be connected as the supply to the system.
Piping must be installed such that no piping stresses
are transmitted to the boiler. The boiler
shall not be
used as a pipe anchor.
3.8.3 Boiler Water Piping by Installer
Strainer
To avoid possible contamination of the boiler with
dirt, rust or sediment from the system, a strainer
near the boiler inlet is strongly recommended. Even
new systems may contain sufficient foreign material
to eventually reduce the performance of the heat
exchanger. Adequate circulation of good clean wa-
ter is essential to maximum efficiency and long life
of the boiler.
Relief Valve and Piping
Isolating
Valve
Boiler
Drain
Isolating
Valve
Relief Valve
Drain
Union
Strainer
Isolating
Valve
Outlet to
System
Inlet from
Each boiler is supplied with a pressure-relief valve
sized in accordance with ASME requirements. The
relief valve must be piped to a suitable drain prior to
placing the boiler into service and in a manner that
prevents water spray from contacting any person.
Reducing couplings or other restrictions are not per-
mitted in the discharge line. WARNING: Do not
plug or obstruct the discharge of the relief valve.
Low Water Cut-off
The boiler is furnished with a flow-switch-type low
water cut-off as required by the ASME BPV Code,
Section IV; no field piping is required. If the flow
switch does not sense water flow, the boiler will
shut down and a red indicator will be illuminated on
the control panel.
Installation of an external low water cutoff or man-
ual reset low-water switch may be required by cer-
tain codes or in certain installations. Consult your
local code for details.
WARNING!
Never install a valve that can isolate the low water
cut-off from the boiler.
Drain Valve and Piping
The boiler is not provided with external drain con-
nections. A drain valve should be installed near the
inlet (system return) connection to the boiler and
piped to a suitable floor drain. The boiler can be
completely drained through the bottom header by
removing the flush plug in the bottom end plate.
This plug may also be used to flush accumulated
sediment from the bottom of the boiler.
3.8.4 Flushing and Filling
Flushing the System
Before filling the boiler, flush the system to remove
the debris. Clean and flush old piping thoroughly
before installing the boiler as recommended by your
water conditioning or chemical treatment supplier.
System
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