8
SECTION III –INSTALLATION AND OPERATION OF STERLCO
TEMPERATURE CONTROL VALVES
WARNING / CAUTION
HANDLE GENTLY. Temperature control valves are instruments, not pipe fittings. A dent in
the body or a sharp bend in the capillary may prevent them from operating. Do not use pipe
wrenches. Do not subject controls to water-hammer conditions or excessive pressures.
BULB LOCATION
This is perhaps the most important factor in good installation. The entire bulb, not just part
of it, must be exposed to the fluid of which the temperature is to be controlled. In a tank, it
must be in a representative location not in a comer which may be warmer or cooler than the
rest of the tank. The temperature at the bulb is the only one which can be controlled.
VALVE LOCATION (HEATING OR DIRECT ACTING CONTROL)
In supply line close to inlet. When heating with steam always use a float and thermostatic
trap at the condensate outlet from the heating equipment. Do not install the control valve at
the condensate outlet; water-hammer or poor control may result.
VALVE POSITION
Preferably with adjusting screw at top but can usually be used in any other position. If
possible, let capillary run downward from valve to bulb. All valve bodies have arrows
showing direction of flow. If installed backward, they will be noisy or inoperative.
CAPILLARY LOCATION
Not next to a steam line or in a cold draft. If the capillary is exposed to extreme
temperatures, it may be desirable to wrap it with insulating material.
STRAINERS
A ‘Y’ Strainer should always be installed just ahead of the control valve to protect it from
large particles of dirt and the system must be kept free of sediment, scale, etc.
ADJUSTMENT
Temperature adjustment within the range of the control is made by simply turning an
adjusting screw in the direction indicated on the valve body or nameplate. Turn the screw
only a little at a time, then let temperatures reach equilibrium before adjusting further.
OPERATION
Remember that this is a modulating control. It does not alternately open wide and shut tight
like an electrical control device. Rather, it opens gradually wider and wider in relation to the
difference between the actual bulb temperature and the bulb temperature at which the valve
is closed. In normal operation, the control valve remains in a constant, partially open
position which is automatically adjusted whenever conditions require it.
MAINTENANCE
The only servicing normally required is to keep the control clean. The valve can be inspected
and cleaned by access through the inlet and outlet, without disassembly. The bulb must not
become coated with any substance which interferes with the transmission of heat.
If repairs are needed, we recommend that these controls be returned to our factory for
reconditioning. Skilled workmen, with proper tools, replacement parts, and testing facilities
will do a good job more economically than it can be done in the field. These controls are
simple to disassemble and assemble for a person who is familiar with them. An
inexperienced worker will sometimes damage them by incorrect handling, and usually
replacement parts, which are not available in the field, will be required. If for any reason it is
necessary to disassemble one of these controls, please write us for detailed assembly
drawings and instructions.
If a control has to be returned for repairs, please tell us as much as possible about what
appears to be wrong, and ship it "as is" without disassembling it and possibly damaging
good parts. This will help us to do the best and most economical work, and to advise you
how to avoid further trouble.
