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31-5000734 Rev. 0
SERVICE MANUAL
NF80XV Gas Furnace
This is a safety alert symbol and should never be ignored. When you see this symbol on labels or in manuals, be alert to
the potential for personal injury or death.
Table of Contents
Technical Specifications
..............................................3
Blower Performance ....................................................4
Blower Performance ....................................................5
Parts Arrangement.......................................................6
Unit Components .........................................................7
Diagnostic LED Codes ..............................................12
Indoor Blower Motor ..................................................20
Heating Components .................................................24
Placement and Installation ........................................27
Start-Up .....................................................................27
Heating System Service Checks ...............................28
High Altitude ..............................................................30
Typical Operating Characteristics ..............................31
Maintenance ..............................................................32
Wiring and Sequence of Operation ...........................34
Program Unit Capacity Size Modes...........................42
Troubleshooting .........................................................43
NF80XV series units are 80% efficiency gas furnaces used
for upflow or horizontal applications only, manufactured with
heat exchangers formed of aluminized steel. NF80XV units
are available in heating inputs of 40,000 to 100,000 Btuh
and cooling applications up to 5 tons. Refer to Engineering
Handbook for proper sizing.
Units are approved for installations up 7500 ft and factory
equipped for use with natural gas only. NF80XV model units
are equipped with a two-stage variable speed integrated
control. NF80XV unit meets the California Nitrogen Oxides
(NOx) Standards and California Seasonal Efficiency
requirements. All units use a redundant gas valve to assure
safety shut-off as required by C.S.A.
All specifications in this manual are subject to change.
Procedures outlined in this manual are presented as a
recommendation only and do not supersede or replace
local or state codes. In the absence of local or state codes,
the guidelines and procedures outlined in this manual
(except where noted) are recommendations only and do not
constitute code.
Improper installation, adjustment, alteration, service or
maintenance can cause property damage, personal injury
or loss of life. Installation and service must be performed
by a licensed professional HVAC installer or equivalent,
service agency, or the gas supplier.
WARNING
As with any mechanical equipment, contact with sharp
sheet metal edges can result in personal injury. Take
care while handling this equipment and wear gloves and
protective clothing.
CAUTION