INSTALLATION INSTRUCTIONS
G1D91BU, G1D93BC, G1D93BU, CG90CB, & CG90UB
High Efficiency 90+ Condensing Gas Furnace
Improper installation, adjustment, alteration, service, or maintenance can cause
injury or property damage. Refer to this manual. For assistance or additional informa-
tion, consult a qualified installer, service agency, or the gas supplier.
WARNING
Do not store combustible materials, including
gasoline and other flammable vapors and
liquids, near the furnace, vent pipe, or warm
air ducts. The homeowner should be cau-
tioned that the furnace area must not be
used as a broom closet or for any other
storage purposes. Such uses may result in
actions that could cause property damage,
personal injury, or death.
WARNING
This furnace is not approved for installation in
a mobile home. Do not install this furnace in a
mobile home. Installation in a mobile home
could result in actions that could cause prop-
erty damage, personal injury, or death.
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The installation of the furnace, wiring, warm air ducts, venting, etc. must conform to the requirements of the
National Fire Protection Association; the National Fuel Gas Code, ANSI Z223.1/NFPA No. 54 (latest edition)
and the National Electrical Code, ANSI/NFPA No. 70 (latest edition) in the United States; CSA B149.1
(latest edition) Natural Gas and Propane Installation Codes and the Canadian Electrical Code Part 1, CSA
22.1 (latest edition) in Canada; and any state or provincial laws, local ordinances (including plumbing or
wastewater codes), or local gas utility requirements. Local authorities having jurisdiction should be con-
sulted before installation is made. Such applicable regulations or requirements take precedence over the
general instructions in this manual.
# 45466K003
WARNING
SAFETY ................................................. 2
START-UP ............................................ 19
OPERATION ........................................ 20
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IMPORTANT
TABLE OF CONTENTS
Manufactured By
A.A.C.
A Lennox International Company
421 Monroe Street
Bellevue, OH 44811
Page 1
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Do you have a question about the G1D91BU and is the answer not in the manual?
Questions and answers
My furnace starts working but stop after 5 minutes. I have tried restarting the system and leaving it to cool, but that didn't work.
A Lennox furnace with part number G1D91BU could stop working after 5 minutes due to several possible issues:
1. Primary Limit Control Activation – If abnormally high circulating air temperatures occur, the normally closed primary limit control may open and shut down the furnace.
2. Auxiliary Limit Control Activation – If there is abnormal reverse airflow, the auxiliary limit control could open, stopping furnace operation.
3. Rollout Switch Activation – If the rollout switch detects excessive heat or flame rollout in the burner box, it may trip and require manual reset.
4. Fault Codes – The furnace has a self-diagnostic LED that indicates fault codes. Checking for stored fault codes may help identify the specific issue.
5. Ignition Lockout (7 Flashes) – If ignition fails multiple times, the control may enter a lockout state, shutting down the furnace.
6. Flame Dropout Issues (8 Flashes) – If the flame sensor detects too many flame dropouts, the control may enter a lockout condition.
7. Incorrect Line Voltage Phasing (9 Flashes) – If the control detects incorrect voltage phasing, it may shut down the furnace.
To diagnose the exact cause, check the LED fault codes on the control board and inspect the limit controls and rollout switch.
This answer is automatically generated