The assembly comprises a housing 14 generally containing {TAIL ~ a propane or natural gas fired furnace} 16 with {HEAD ~ supply duct} 18 
The assembly comprises a housing 14 generally containing { TAIL ~ a propane or natural gas fired furnace } 16 with { HEAD ~ supply duct } 18
OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD OTH