
85
Rev. 2
SERVICING
S-16
CHECKING ORIFICES
A predetermined fixed gas orifice is used in all of these fur-
naces. That is an orifice which has a fixed bore and position
as shown in the following drawing.
No resizing should be attempted until all factors are taken
into consideration such as inlet an manifold gas pressure,
alignment, and positioning, specific gravity and BTU con-
tent of the gas being consumed.
The only time resizing is required is when a reduction in
firing rate is required for an increase in altitude.
Orifices should be treated with care in order to prevent dam-
age. They should be removed and installed with a box-end
wrench in order to prevent distortion. In no instance should
an orifice be peened over and redrilled. This will change the
angle or deflection of the vacuum effect or entraining of pri-
mary air, which will make it difficult to adjust the flame prop-
erly. This same problem can occur if an orifice spud of a
different length is substituted.
WARNING
Disconnect Gas and Electrical Power Supply:
1. Check orifice visually for distortion and/or burrs.
2. Check orifice size with orifice sizing drills.
3. If resizing is required, a new orifice of the same physical
size and angle with proper drill size opening should be
installed.
A
GAS
STREAM B
The length of Dimension "A" determines the angle of Gas
Stream "B".
DENT OR
BURR
GAS
STREAM B
A dent or burr will cause a severe deflection of the gas stream.
S-17
HIGH ALTITUDE APPLICATION (USA)
For those altitudes starting at 6000 feet for "C" and "D" model
furnaces, or 7500 feet for "A" and "B" model furnaces, it will
be necessary to replace the pressure switch and orifices.
For those altitudes starting at 3000 feet for "S"and "V" model
furnaces, it will be necessary to replace the pressure switch
and orifices.
These changes are required to compensate for the reduc-
tion in atmospheric pressure (less available air for combus-
tion) as the altitude increases.
The following chart gives the orifice drill size and high alti-
tude kit required for different elevations.
GUIA/B
GCIA/B
0 to
7500 ft.
Nat. #43
Original Equipment
Factory Installed
(10716003 orifices)
GUIC/D
GCIC
0 to
6000 ft.
Nat. #43
Original Equipment
Factory Installed
(10716003 orifices)
GUIS
GCIS
GUIV
0 to
3000 ft.
Nat. #43
Original Equipment
Factory Installed
(10716003 orifices)
GUIA/B
GCIA/B
7500 to
11000 ft.
Nat. #45
HANG07
High Altitude Orifice Kit
(uses 10716005 orifices)
GUIC/D
GCIC
6000 to
11000 ft.
Nat. #45
HANG07
High Altitude Orifice Kit
(uses 10716005 orifices)
GUIS
GCIS
GUIV
3001 to
7000 ft.
Nat. #44
HATS01-05
High Altitude Orifice Kit
(uses 10716004 orifices)
GUIS
GCIS
GUIV
7001 to
8500 ft.
Nat. #45
HATS06-09
High Altitude Orifice Kit
(uses 10716005 orifices)
GUIA/B
GCIA/B
0 to
7500 ft.
Propane
#55
LPTK06, 07, 07A or 09
Propane Conversion Kit
(uses 10716009 orifices)
GUIC
GCIC
0 to
6000 ft.
Propane
#55
LPTK07, 07A or 09
Propane Conversion Kit
(uses 10716009 orifices)
GUID
0 to
6000 ft.
Propane
#55
LPTK08 or 09
Propane Conversion Kit
(uses 10716009 orifices)
GUIS
GCIS
GUIV
0 to
7000 ft.
Propane
#55
LPTK07A or 09
Propane Conversion Kit
(uses 10716009 orifices)
GUIA/B
GCIA/B
7500 to
11000 ft.
Propane
#56
HALP05 OR 09
Propane Conversion Kit
(uses 10716010 orifices)
GUIC
GCIC
6000 to
11000 ft.
Propane
#56
HALP09
Propane Conversion Kit
(uses 10716010 orifices)
GUID
6000 to
11000 ft.
Propane
#56
HALP07 OR 09
Propane Conversion Kit
(uses 10716010 orifices)
GUIS
GCIS
GUIV
7001 to
8500 ft.
Propane
#56
HALP09
Propane Conversion Kit
(uses 10716010 orifices)
High altitude pressure switches and kits are listed in the
Pressure Switch Usage and Trip Point Chart.
Содержание GCIA045A30
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