Downflow and upflow furnaces

Heating · Heat Exchangers · printed page 122 (PDF page 123)

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Book index entries

Downflow and Upflow Furnaces Upflow and Downflow Upflow and Downflow Furnaces

Text in the illustration

return
vent connector
air filters
blower
draft hood
heat exchanger
gas valve
gas burners
air flow
supply
downflow gas furnace
often used above short crawlspaces where access is limited
air filter
upflow gas furnace
most common -typically located in basement

Generated explanation

The illustration compares downflow and upflow gas furnaces, showing their internal components and return and supply airflow paths. In the downflow furnace, return air enters at the top through filters, and a blower above the heat exchanger moves air downward to supply ducts beneath the floor. In the upflow furnace, return air travels down a side duct through a filter to a blower below the heat exchanger, then moves upward to an overhead supply duct. Both furnaces show gas burners, a gas valve, a heat exchanger, a draft hood, and a vent connector. Notes associate the downflow arrangement with short crawlspaces with limited access and the upflow arrangement with basement installations.

Components

downflow gas furnace upflow gas furnace return air ducts supply air ducts air filters blower heat exchanger gas burners gas valve draft hood vent connector floor framing furnace support pad

Materials

sheet metal wood concrete