Product Overview

2 T26 Series Line Voltage Thermostats Product/Technical Bulletin
I
ntroduction
IMPORTANT: All T26 Series thermostats are
designed for use only as operating
controls. Where an operating control
failure would result in personal injury
and/or loss of property, it is the
responsibility of the installer to add
devices (safety, limit controls) or
systems (alarm, supervisory
systems) that protect against, or warn
of, control failure.
The T26 standard model thermostats provide SPDT
control for heating, cooling, or heating and cooling
applications. The T26 has a thermoplastic cover with
an Allen-head locking screw to discourage
unauthorized tampering.
The thermostat consists of a liquid filled sensing
element, which has excellent sensitivity to surrounding
air temperature changes. Coupled with a highly
efficient diaphragm and lever mechanism, the element
operates an enclosed narrow differential Pennswitch.
An adjusting knob and easy-to-read dial allow quick
selection of the desired setpoint. The thermostat is
supplied with the faceplate installed for vertical
mounting and knob adjustment. However, a horizontal
faceplate is enclosed for horizontal mounting and knob
adjustment if desired.
O
perating Differential
The operating temperature differential of any self-
contained thermostat depends on the following:
• the velocity of air over the thermostat
• the rate of temperature change to which the
thermostat is subjected
• the current flowing through the thermostat
(amperage load)
• whether the thermostat is operating heating or
cooling equipment
Figures 2 and 3 show the operating temperature
differentials of the T26 thermostats under various
load conditions. The amperage loads are based on
the electrical ratings in Table 1. The air velocity
was 25 ft/min (0.127 m/sec) and the rate of
temperature change was 6 F° (3.3 C°) per hour.
For air velocities greater than 25 ft/min and/or rates of
temperature change less than 6 F° (3.3 C°) per hour,
the operating differentials will be less than what is
shown in Figures 2 and 3.
5
4
3
2
1
0
0246810121416182022
Amperage Load
Operating Differential F°
T26B and T26T Heating
T26A and T26S Heating
2.2
1.1
Operating Differential C°
Note: The dark shading applies to non-inductive loads only.
Figure 2: Operating Differentials for T26A, T26B, and
Heating Side for T26S and T26T
5
4
3
2
1
0
0246
8
Amperage Load
Operating Differential F°
T26T Cooling
T26J and T26S Cooling
2.2
1.1
Operating Differential C°
Figure 3: Operating Differential for T26J and
Cooling Side for T26S and T26T
The heavy lines in Figures 2 and 3 are the nominal
operating temperature differential. Production
thermostats may vary from the norm as indicated by
the shaded areas.
I
nstallation
Supplies Needed
• 2 x 4 in. (51 x 102 mm) wall box (field supplied)
• screwdriver (slotted standard)
• marking pencil
• wire strippers