Chromalox PK410-1 installation instructions Installation Instructions, General

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	6”
Fail-Safe
	53/8”
Device.

21/2”

WR-80

40 to 80°F 21/4”

UL Listed

Specifications – Table A

29/16”

WR-90

20 to 90°F UL Listed

	Range			Maximum Rating
Model	(°F)	120Vac	† 115Vac	240Vac	† 230Vac	277Vac	480Vac
WR-80	40-80		125va pilot		125va pilot		125va pilot
		25 amps	duty (use	22 amps	duty (use	18 amps	duty (use
WR-90	20-90	or 3000	with d-c	or 5280	with d-c	or 5000	with a-c
		total watts	contactor)	total watts	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.