IMMERSION WELLS AND COMPRESSION FITTINGS
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.
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.
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.
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.
Securing Bulb in Well
Sizing
REMOTE BULB APPLICATIONS
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.
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.
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.
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 Honeywell 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 Honeywell
TRADELINE® direct-insertion controllers.
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.
SETSCREW
BACK
OF
CASE
BOILER
WALL
IMMERSION
WELL CLAMP
2. Check the ratings given in the instructions and on the
product to make sure the product is suitable for your
application.
WELL
SHELL
WELL
SPUD
3. Installer must be a trained, experienced service techni-
WELL
cian.
CLAMP
SCREW
WELL
ADAPTER
M17261
4. After installation is complete, check out product opera-
tion as provided in these instructions.
SENSING BULB
Fig. 3. Mounting direct insertion controller
case on well spud.
WARNING
Contact with hot liquid can cause severe injury or
death.
Drain system before beginning well or compression
fitting installation.
Severe Scalding Hazard.
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.
68-0040—04
8
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