Model Evolution - American Standard *UD Series Operation Manual

40" Residential Gas Furnace Evolution
Third Quarter 1991 –
Second Quarter 1992 –
Second Quarter 1993 –
Third Quarter 1993 –
Fourth Quarter 1993 –
Second Quarter 1994 –
Third Quarter 1994 – TUJ-A 40" radiant sense ignition model introduced. Model converts to horizontal left
Fourth Quarter 1994 –
Second Quarter 1995 –
First Quarter 1996 – TUE/TDE-A-K up graded to 80% AFUE. These models have remote flame rectification
Fourth Quarter 1997 – Introduced the Silicon Nitride Ignitor and appropriate controls.
UD-R and UD-C 40" induced draft upflow models introduced to replace the TUD-B
linear burner upflow models.
DD-R and DD-C 40" induced draft downflow/horizontal models introduced to
replace the TDD-B linear burner downflow models and the THP, THS and THD series
horizontal models.
UE 40" single stage radiant sense ignition model introduced.
UC-C and DC-C 40" condensing models introduced to replace the TUC-B and TDC-B
linear burner condensing models. ( UC-C models convert to horizontal left, DD-C
models convert to horizontal right.)
DE 40" single stage radiant sense ignition models introduced.
UX-C and DX-C 40" direct vent condensing models introduced to replace the
UX-B and DX-B linear burner direct vent models.
or horizontal right and is shipped without bottom panel and filter. Model discontinued
third quarter 1995.
UY-R-V 40" two-stage, direct vent variable speed condensing models introduced to
replace the TUC/TDC-B-V variable-speed models.
DD-C-C Downflow/Horizontal and UD-C-H Upflow/Horizontal models introduced.
Previous upflow models were for upflow applications only. The UD-C-H and TUE-A-H
models are also approved for horizontal installation. The DD-C-C and UD-C-H
models are equiped with the "enhanced" integrated furnace control with 120 VAC
humidifier output, adaptive hot surface ignitor timing and improved fault tolerances.
ignition control systems.
For all models equipped with the Silicon Nitride
Hot Surface Ignitor, see Pub. No. 34-3405.
Models maybe an A or T or F
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