Effective: February 1992
ATTENTION: To ensure safe and proper performance,
read these instructions carefully before attempting to
install or operate this Fenwal product. Please retain for
The shell of each THERMOSWITCH® Controller
contains the catalog number, the current rating, the
temperature range, and the contact arrangement.
Controllers that are component recognized or listed by
Underwriter's Laboratories or certified by the Canadian
Standards Association (CSA) will also bear the symbol of
the approving agency. In addition, UL component
recognized units may have a "4" as the first digit of the
The fifth digit of the catalog number describes whether
contacts open or close on temperature rise. If contacts
open on temperature rise, the fifth digit of the number is
an even number (17000, 17002, etc.). If contacts close
on temperature rise, the fifth digit is an odd number
(17021, 17023, etc.).
If the fourth digit is "2" or 7" (e.g., 17021, 17071), the
controller is compression operated. Compression units
that close on temperature rise are recommended if over-
ranging is anticipated. Low temperature units [-100 to
+400°F (-73 to +2040C)] can be over-ranged to 500°F
(2600C) and high temperature units [-100 to +600°F (-73
to + 316°C)] over-ranged to 700°F for intervals not
exceeding one hour.
THERMOSWITCH Controllers are supplied in five basic
head configurations - Cartridge, Block Head, Hex Head,
Coupling Head and Circular Flange. See Figure 1.
To avoid restricting shell expansion when making
installations in solid metal blocks, a 0.625 in diameter
reamed hole for 5/8 in standard units or a 0.812 in
diameter reamed hole for 13/16 in heavy duty units is
recommended. See the following specific controller style
listing for additional installation instructions.
Cartridge (Style 1) - Hole should have a short spline to
receive the 0.125 in diameter locating pin. This prevents the
unit from rotating when the adjusting sleeve is turned. The
cartridge style may be used for surface control if inserted
into a Fenwal surface mounting well (Cat. No. 11100-2).
Block Head (Style 2) - Mounted in a similar manner to the
cartridge type. If the unit is to be inserted into a reamed
hole, mount two short pins on either side of the hole. The
pins should rest against the sides of the block head to
prevent rotation of the unit.
Hex and Coupling Head (Styles 3 and 4) - Installed like
any pipe fitting. If installed in a pipe tee, the tee should be
large enough to allow adequate circulation of the fluid
around the temperature-sensitive section of the controller.
See Table 1 for maximum torque values.
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