The temperature in the piping varies constantly during the operation causing expansion
and contraction of the pipes. The temperature differences also cause condensation in
the pipe line.
In long pipe runs the pipe line length can change by over 1" per 212° F. Thus extra load
builds up on pipe connection point, which may result in component failures.
Apply the following rules of thumb for the construction:
● Use carbon or stainless steel for FGR piping. Pipe wall must not be too thick.
● Route the duct with a minimum number of elbows, still allowing a normal expansion
and contraction of the duct. Place pipe supports to avoid excessive load to pipe
connection.
● Leave space for the pipe joint movement during the expansion and contraction of
the duct.
● Provide condensation drains, if needed. Check the drain volume needs.
To mount FGR duct system:
1. Place the inlet to the stack as close as possible to the boiler or economizer. Set
cutting in 45° angle.
2. Set control damper close to the burner.
3. Finish the FGR duct pipe joint carefully with seal welding, flange or screw
connection. Make sure that the joint is tight and no air can enter the duct.
4. Place condensate drains both at the beginning and the end of pipe line.
5. Install one drain upstream from the FGR control valve, and another in the FGR
shut-off valve, if used.
6. In case of heavy condensation, add a condensate drain to the bottom of the
housing.
7. Anchor supports to provide stability in the duct.
Excessive load on the pipeline may cause damage to the burner or its
components. The construction must be self-supporting.
M4248 2316EN
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