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508146-01
Issue 2051
Page 1 of 7
0
SERVICE MANUAL
GUH97M
Gas Furnace
(P) 508146-01
*P508146-01*
Table of Contents
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Joint Cementing Procedure
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2
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Typical Operating Characteristics
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Wiring and Sequence of Operation
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.
Electric shock hazard.
Can cause injury or death. Before attempting
to perform any service or maintenance,
turn the electrical power to unit OFF at
disconnect switch(es). Unit may have
multiple power supplies.
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
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
GUH97M series units are high-efficiency upflow,
horizontal right and left) gas furnaces equipped with
variable capacity gas valve, variable speed combustion
air inducer and variable speed indoor blower motor. All
models are designed only for direct vent (dual pipe)
venting system. GUH97M units are available in heating
capacities from 66,000 to 132,000 Btuh (19.3 to 38.6 kW)
and cooling applications from 2 to 5 tons (7.0 kW to 17.5
kW). Refer to Technical Specifications for proper sizing.
Units are factory-equipped for use with natural gas. Kits
are available for conversion to LPG operation. GUH97M
models include a variable capacity integrated control that
can be used with Comfort-Aire/Century Standard
thermostat. All GUH97M units meet the California
Nitrogen Oxides (NOx) Standards and California
Seasonal Efficiency requirements.
All specifications in this manual are subject to change.
Procedures outlined in this manual are presented as
recommendations 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.
Field Wiring Applications with Conventional
Thermostat......................................
Sequence of Operation and Troubleshooting Flow