Flue Exhaust Piping To Vent - Watts AERCO EXT Installation, Operation & Maintenance Manual

Modulex EXT Commercial Series
CHAPTER 4: Installation Instructions

4.19 Flue Exhaust Piping to Vent

In a condensing boiler the flue exhaust is evacuated at a very low temperature (maximum of about
183°F / 84°C). Thus, it is necessary that the chimney be impermeable to the condensate of the
combustion products and be made of corrosion resistant materials.
The different joints must be well sealed and equipped with suitable gaskets in order to prevent the
escape of condensate and prevent the ingress of air.
To determine the proper cross section and height dimensions of the flue exhaust piping, refer to
national and local codes.
In order to prevent the formation of ice during the operation, the temperature of the internal wall of the
flue exhaust system should not be below 32 °F (0 °C) throughout its length.
For efficient venting of the combustion exhaust and to address condensation due to lower external
temperatures, ensure that combustion condensation is discharged into the boiler condensate tray or
into another separate collection pan according to the installation.
A test nipple, for measuring combustion gases, should be installed onto the first three feet of the
exhaust manifold flue. To do this, a hole with a diameter of 0.83'' is drilled in a convenient location for
testing and the test nipple hardware assembled to the Flue pipe as shown.
Figure 4-12: Installation of Test Nipple into Flue Manifold Piping
NOTE: Damage caused by mistakes in installation, failure to complete the instructions as written, or
the improper use of the flue system are not the responsibility of the supplier.
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