Product Overview

IMMERSION WELLS AND COMPRESSION FITTINGS
68-0040—05 8
he nominal length of the spud, including the full length of the
threads and the hex, defines the insulation depth. Depending
on the characteristics of the tapping, 1/8 to 1/2 in. of the
threaded end of the spud can extend into the controlled
medium. Consider this additional length when determining
how far the well extends into the controlled medium.
The length of the well shell starting at the end of the spud
defines the insertion length. This is the active part of the well
where the fastest heat transfer occurs. The bulb should be
the same length as the well shell; however, the well shell can
be longer, but not shorter, than the length of the bulb. Longer
shells require inserting the bulb until the end touches the well
bottom. Shorter shells do not expose the full length of the
bulb to the temperature of the controlled medium, inhibiting
proper temperature controller operation.
Securing Bulb in Well
REMOTE BULB APPLICATIONS
Securing the capillary at the spud with a spring clip or a
mounting clamp holds the sensing bulb securely in place.
See Fig. 1. Use the spring-loaded clip on well spuds with no
mounting flange. Slip it over the capillary and snap it in place
in the end of the spud. The mounting requires sizing to fit
both the spud and the capillary diameter. The mounting
clamp requires wells with a mounting flange at the spud end.
The jaws adjust to fit both 1/2 and 3/4 in. spuds, and it holds
a 5/64 in. capillary. Wells are available with and without the
matching spring clip or mounting clamp. This mounting
hardware is also available separately.
A few wells have a setscrew in the spud. These wells are
designed for use on controllers with an armored capillary that
has a brass plug at the sensing bulb end; for example,
R8182H,J.
DIRECT INSERTION APPLICATIONS
Most direct insertion controllers include provision for
clamping the controller case on the immersion well spud.
This requires a well spud with a mounting flange at the end. If
the well spud has a setscrew, but no mounting flange, a
124904 Well Adapter can provide the necessary flange. See
Fig. 3. The well adapter is shipped with several direct-
insertion controllers.
Fig. 3. Mounting direct insertion controller
case on well spud.
Capillary Compression Fittings
A capillary compression fitting includes a spud, several
aligning washers, a neoprene packing ring and a packing nut.
The spud is internally threaded to hold the packing material
and the packing nut and externally threaded to fit standard
boiler tappings. The washers and packing ring are sized to fit
a particular capillary diameter.
Capillary compression fittings are used to replace an
immersion well when the sensing bulb of a remote bulb
controller requires direct insertion into the controlled
medium. The fitting seals around the capillary. However,
compression fittings cannot seal off against as much
pressure as immersion wells. Capillary compression fittings
can be used in duct applications to minimize air leakage from
the duct; a waste nut is recommended to provide a secure
mounting.
Material Selection
Capillary compression fittings are available in brass and
stainless steel. In hydronic applications, brass fittings with
copper sensing bulbs are used and stainless steel is used
with all other fittings to minimize electrolytic action.
Sizing
Capillary compression fittings must fit the tapping and the
capillary diameter. Because the spud must slip over the bulb
during installation, 11/16 in. bulbs require 3/4 in. spuds.
Element Holders
Bulb holders are used to support a remote bulb and capillary
in a duct, but are not suitable for hydronic applications. A
bulb holder must be selected according to the length needed
to support the bulb in the main airstream and the need for
plugging the opening in the duct wall.
For best response, string averaging elements evenly back
and forth across the duct. The element is held in place with
either perforated pipe strap or 314439 Mounting Clips. If
access to the duct is limited, use the 7640HX Duct Mounting
Kit. Always use a grommet to protect the element from
abrasion where it enters the duct.
NOTE: To minimize heat loss through the fitting, use a
waste nut and compression fitting.
INSTALLATION
When Installing this Product…
1. Read these instructions carefully. Failure to follow
them could damage the product or cause a hazardous
condition.
2. Check the ratings given in the instructions and on the
product to make sure the product is suitable for your
application.
3. Installer must be a trained, experienced service techni-
cian.
4. After installation is complete, check out product opera-
tion as provided in these instructions.
M17261
BACK
OF
CASE
WELL
CLAMP
SCREW
WELL
ADAPTER
IMMERSION
WELL CLAMP
SENSING BULB
SETSCREW
WELL
SPUD
BOILER
WALL
WELL
SHELL