Page 1
Corp 9912−L5
Revised 08−2004
AFUE - Up to 80.5%
Heating Input - 45,000 to 120,000 Btuh (13.2 to 35.2 kW)
Add-On Cooling - 1 thru 5 Tons (3.5 to 17.6 kW)
F8AUH
Gas Furnaces
Up-Flow/Horizontal
SERVICE MANUAL
F8AUH series units are mid−efficiency gas furnaces used
for upflow or horizontal applications only, manufactured
with tubular heat exchangers formed of aluminized steel.
F8AUH units are available in heating capacities of 45,000 to
120,000 Btuh and cooling applications up to 5 tons. Refer to
Engineering Handbook for proper sizing.
Units are factory equipped for use with natural gas. Kits are
available for conversion to LPG operation. F8AUH model
units are equipped with a hot surface silicon carbide ignition
system. The F8AUHX unit meets the California Nitrogen Ox-
ides (NO
x
) Standards and California Seasonal Efficiency re-
quirements. All units use a redundant gas valve to assure
safety shut−off as required by A.G.A. or C.G.A. Units may be
installed in upflow or horizontal position.
All specifications in this manual are subject to change. Pro-
cedures outlined in this manual are presented as a recom-
mendation 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 recommended only and do not constitute
code.
TABLE OF CONTENTS
Introduction
1
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Specifications
2
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Blower Data
4
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Horizontal Venting
6
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
High Altitude
6
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Parts Identification
7
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
I Unit Components
8
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
II Installation
14
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
III Start Up
14
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
IV Heating System Service Checks
14
. . . . . . . . . . . . . .
V Typical Operating Characteristics
16
. . . . . . . . . . . . . .
VI Maintenance
17
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
VII Wiring and Sequence of Operation
19
. . . . . . . . . . . .
VIII Control Board Troubleshooting Guide
23
. . . . . . . .
