Installation Instructions
4
WR
(Supersedes PK410)
PK410-1
161-048634-001
JUNE, 1989
Type WR Room Thermostat
23/
4
”
21/
2
”
Note —
WR-80 is
not a
Fail-Safe
Device.
6”
53/
8
”
21/
2
”
29/16”
WR-80
40 to 80°F
UL Listed
21/
4
”
WR-90
20 to 90°F
UL Listed
Specifications – Table A
Range
Maximum Rating
Model
(°F)
120Vac
† 115Vac
240Vac
† 230Vac
277Vac
480Vac
WR-80
40-80
125va pilot
duty (use
with d-c
125va pilot
duty (use
with d-c
125va pilot
duty (use
with a-c
25 amps
or 3000
total watts
22 amps
or 5280
total watts
18 amps
or 5000
WR-90
20-90
contactor)
contactor)
total watts contactor)
† d-c ratings not UL listed
GENERAL
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.
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.
© 2010 Chromalox, Inc.
Download from Www.Somanuals.com. All Manuals Search And Download.
CALIBRATION
SETTING
WR-90 controls have an adjustable differential. The movable
indicator points to the temperature at which the contacts open. The
fixed indicator points to the temperature at which the contacts close.
The difference between these two indicators is the differential.
UNITING LIQUID IN THERMOMETER
Sometimes the red liquid inside the thermometer on the WR-
80 becomes separated during shipment. The thermometer will not
read correctly when this red liquid is separated at any point. If the
red liquid in the thermometer of this thermostat has become sepa-
rated it may be reunited as follows:
To set the control, proceed as follows:
1. Remove the thermostat from the wall, and straighten out the
four prongs so the cover can be removed to expose the ball of
the thermometer.
1. Use screwdriver in slot and turn the dial so the fixed indicator
“B” points to the temperature at which heating is to start.
2. Turn the differential adjusting screw “C” until the movable
indicator “D” points to the temperature at which the heating is
to stop.
2. Hold the lighted end of a cigarette or a match at such a distance
from the SIDE of the ball of the thermometer so the red liquid
rises SLOWLY in the stem of the thermometer.
3. When the lowest separation goes into the reservoir, immedi-
ately remove the heat and blow on the thermometer.
Figure 5
Figure 4
CAUTION: If there is more red liquid in the stem of the ther-
mometer above the lowest separation than there is below it, it is
best to replace the thermometer.
Download from Www.Somanuals.com. All Manuals Search And Download.
Limited Warranty:
Please refer to the Chromalox limited warranty applicable to this product at
1347 HEIL QUAKER BLVD., LAVERGNE, TN 37086
Phone: (615) 793-3900
Download from Www.Somanuals.com. All Manuals Search And Download.
|