1/2 400-276-002-B
RC840T
Application
The RC840T Electric Heating Relay is designed to control a line
voltage resistive load from a low voltage thermostat. The RC840T
relay has a built-in 24 V transformer and is compatible with 3-wire
(R,C,W) thermostats as well as 2-wire mechanical and battery-
operated thermostats.
The RC840T operates silently and can be installed in bedrooms,
living rooms, or any other occupied area without disturbing
occupants. On a call for heat, the relay is immediately activated;
there is no delay. This increases temperature control and comfort.
NOTE: Not recommended for fast-cycling modulated regulation. For
fast-cycling heating equipment, we recommend the RT850 or
RT850T (integrated 24 V transformer) Solid State Relay.
Installation
The RC840T must be installed in an area where the temperature is
between -4°F and 140°F (-20°C and 60°C).
The RC840T can be installed on the side of an electrical box (1) or a
distribution panel or inside the wiring compartment of an electric
baseboard (2).
All wiring must comply with national and local electrical
code regulations.
Installation should be carried out by an electrician.
Disconnect power supply before installing the relay to pre-
vent electrical shock.
nSecure relay to the mounting surface using the two mounting
brackets. Use the supplied lock nut to secure the relay to the
junction box.
oWire the relay and connect according to typical wiring diagrams
(refer to figures 1 & 2).
pOnce mounting and wiring have been completed, return power
to the heating system and test the installation.
qIncrease the thermostat temperature to activate the relay. Allow
system operation long enough to proof installation. Once
installation has been proofed, set temperature to normal
setpoint.
Typical Wiring Diagrams
Figure 1: Connection to a 2-wire low voltage thermostat
Figure 2: Connection to a 3-wire low voltage thermostat
Figure 1: Installation on
the side of an electrical
box
Figure 2: Installation inside
the wiring compartment of a
baseboard
For proper installation, use
a screw and a washer.
You must provide an overload protection and
disconnect as required.
You must provide an overload protection and
disconnect as required.
RC840T - Installation Instructions
On/Off Switching Electric Heating Relay with Built-in 24 V Transformer
