Roof Jacks & Extensions.
Nordyne/Miller/Intertherm Flat Roof Jack 15-23 in (FM-903658)
This roof jack has an all-weather crown for flat or low-sloped roofs. It is adjustable from 15" to 23" when measured from the roof (not ceiling) to the top of the furnace. Installation instructions are included. Outside pipe is 8 3/8" which fits over about an 81/4" pipe on the furnace. The inside pipe is 5 1/8" which fits over about a 5" pipe on the furnace.
Note: This 9036series roof jack is used on almost all Nordyne gas furnaces that are MGHA or newer. Models included are M1, MBHA, MGBA, MGBB, MGHA, MGHB, MMBA, MMBB, MMHA, MMHB, MSBA, MSBB, MSHA and MSHB. Roof jacks are no longer available for MGH or MAC furnaces.