Chromalox PK410-1 Installation Instructions

Note —
WR-80 is
not a
Fail-Safe
Device.
Positive accuracy, long and reliable service, 3° differential.
Heavy-duty, single stage, SPST line voltage snap-acting switch.
Patented hydraulic element. WR-80 has internal sensing element
and thermometer on cover; WR-90 has external, coiled sensing
element but no thermometer. Both have a low position which
drops control point to keep heater off. WR-80 and WR-90 fin-
ished in tough metallic gray with chrome trim; mounting plate
fits outlet or conduit box.
Uses – Automatically controls room temperature by turning elec-
tric air heaters on and off. Can be used to control the air heaters
directly, within thermostat rating. For higher ratings use thermo-
stat with magnetic contactor. Place thermostat on inside wall,
away from undue heating or cooling influences, about 4 feet
above the floor. WR-90 is especially useful in holding lower tem-
peratures, for example, in garages, warehouses, factories, etc.
© 2010 Chromalox, Inc.

Installation Instructions

Type WR Room Thermostat
3
2 / "
4
6"
Specifications – Table A
Range
Model (°F)
WR-80 40-80
WR-90 20-90
† d-c ratings not UL listed
1
2 / "
2
3
5 / "
8
2 1 / "
2
WR-80
40 to 80°F
UL Listed
Maximum Rating
120Vac † 115Vac 240Vac
125va pilot
25 amps duty (use 22 amps
or 3000 with d-c or 5280
total watts contactor) total watts

GENERAL

NOTICE: Type WR thermostats are designed for temperature
control service only. Because they do not fail safe, they should
not be used for temperature limiting duty.
CAUTION: Users should install adequate back-up controls and
safety devices with their electric heating equipment. Where the
consequences of failure may be severe, back-up controls are
essential. Although the safety of the installation is the responsi-
bility of the user, Chromalox will be glad to make equipment rec-
ommendations.
Principle of Operation – Control action of these thermostats is
provided through the principle of liquid volume change. With a
variation in temperature, the liquid in the sensing element
expands or contracts, causing a bellows to actuate the switching
mechanism.
CAUTION: Not for use in hazardous environments
as described in National Electrical Code. Failure to
comply can result in explosion or fire.
4
(Supersedes PK410)
JUNE, 1989
9
2 / "
16
WR-90
2 1 / "
4
20 to 90°F
UL Listed
† 230Vac 277Vac 480Vac
125va pilot 125va pilot
duty (use 18 amps duty (use
with d-c or 5000 with a-c
contactor) total watts contactor)
WR
PK410-1
161-048634-001