Installation and Maintenance Instructions for
T400 & T700 ASHCROFT
®
Snap Action
Switches for Temperature Control
© 2017 Ashcroft Inc., 250 East Main Street, Stratford, CT 06614-5145, USA, Tel: 203-378-8281, Fax: 203-385-0499, www.ashcroft.com
All sales subject to standard terms and conditions of sale. I&M009-10006-10/00 (250-2230G) 12/17
As received, the temperature switch will normally be set to
approximately 90% of the indicated range. After stabilization,
turn the adjustment nut until switch changes mode. Direction of
turning is indicated on a label affixed to the inside of the control
enclosure. When setpoint has been achieved raise and lower
temperature to insure that the setpoint is correct.
After installation of the control replace cover to insure electrical
safety and to protect internal parts from the environment.
T450 and T750 VARIABLE DEADBAND SWITCHES
Deadband is varied by rotating the wheel on the precision switch.
When viewed from the front of the enclosure, rotation
to the left increases deadband – rotation to the right decreased
deadband. Letters on the wheel may be used as a reference.
Deadbands obtainable will vary from 0.5% to 9% of pressure
range depending on range segment.
ADJUSTMENT OF SETPOINT
As received, the temperature switch will normally be set to
approximately 90% of range. Rotate the wheel on the MICRO
SWITCH all the way to the right; this will provide smallest dead-
band. Increase bath temperature to the required setpoint and
turn the adjustment nut until the switch changes mode. Lower
the bath temperature to reset the switch. Rotate the wheel on the
MICRO SWITCH until the desired deadband is obtained. The
upper setpoint will be changing upward with this adjustment.
Lower the bath temperature to reset the switch. Raise the bath
temperature to the desired setpoint and turn the adjusting nut
until the switch changes mode. Lower the bath temperature and
check reset point and deadband.
T428 & T429 MANUAL RESET SWITCHES
Route wire leads from switch terminals so as not to interfere with
or touch reset button.
Note
– As indicated above, adjustment of setpoint is made by
use of
7
⁄
8
˝ nut. Precision switch element mounting screws and
bracket adjusting screw are factory sealed and should not be
tampered with.
