Multi-nozzle combustion assemblies including perforated flame holder, combustion systems including the combustion assemblies, and related methods

A heating unit, comprising:

• a shell defining an interior space of the heating unit;
• one or more integrated combustion assemblies extending into the interior space, each of the one or more integrated combustion assemblies including:
• a plurality of fuel nozzles, each of which is configured to output fuel flow in generally a downstream direction;
• a fuel distribution hub operably coupled to the plurality of fuel nozzles and configured to distribute fuel among the plurality of fuel nozzles;
• a perforated flame holder including a body defining a plurality of apertures that extend between an upstream side of the perforated flame holder and a downstream side of the perforated flame holder, the perforated flame holder being positioned at a selected distance downstream from the plurality of fuel nozzles and defining a flow space between the upstream side of the perforated flame holder and the plurality of fuel nozzles;
• and
• one or more supports extending downstream from the plurality of fuel nozzles and supporting the perforated flame holder at the selected distance from the plurality of fuel nozzles.

A method of upgrading a heating unit, the method comprising:

• removing at least one burner from the heating unit, thereby vacating a burner space therein;
• and
• installing an integrated combustion assembly in the vacated burner space in the heating unit, the integrated combustion assembly including:
• a fuel distribution hub operably coupled to a plurality of fuel nozzles and configured to distribute fuel among the plurality of fuel nozzles, each of which is configured to output fuel flow in generally a downstream direction;
• a perforated flame holder including a body defining a plurality of apertures that extend between an upstream side of the perforated flame holder and a downstream side of the perforated flame holder, the perforated flame holder being positioned at a selected distance downstream from the plurality of fuel nozzles and defining a flow space between the upstream side of the perforated flame holder and the plurality of fuel nozzles;
• and
• one or more supports extending downstream from the plurality of fuel nozzles and supporting the perforated flame holder at the selected distance from the plurality of fuel nozzles.