YOUR HONEYWELL THERMOSTAT
Your new Honeywell CT50A Heating Thermostat will replace most 15
heating system thermostats. The CT5OA will control most gas or oil heating systems
(NOT for heating/cooling or heat pump systems).
Your new Honeywell CT51A Heating/Cooling Thermostat will replace most 15 to
4-wire, heatingkooling system thermostats. The CT51A is suitable only for
heatingkooling systems (NOT for heat pump systems).
Your new Honeywell CT53A Heating Thermostat is suitable for 250,500 or
(mV) heating systems only.
WIRE AND MOUNT
Connect one of the 2 wires from the wall
each of the
terminals on the back
of the thermostat. Tighten the screws.
Connect4wires from thewall to matching terminalson backof thermostat.Tighten
Connect wires to
and W for 750 mV systems. CQnRect to R and Y
P a r 250 or 500
Grasp the thermostat cover at the top and bottom with one hand. Pull
outwardon the topedgeofthe thermostatcover until itsnaps freeofthe thermostat
Carefully remove and discard the red plastic pin located above the mercury switch.
This pin protects this switch during shipment.
the wall with one of the screws supplied, using the top
Place your level across the top of the
level it. Start the second
supplied, in the center of the bo
Recheck for level positioning then firm1
mV systems. Tighten the screws.
If Installing CT50A, CT5lA
MAKE SURE you have the current (anticipator setting) for your system.This is the
number you wrote in the box in step 2. If you were unable
find the current draw
or step 2 this information can be found printed on the primary control at the furnace.
The primary control is usually a gas valve, zone valve, or a relay or burner control box
with the thermostat wires connected
illustrations O f 3 types of primary controls
On the CT50A CTSlA
TOP MOUNTING HOLE
ANTICIPATOR SETTING LEVER
(CT5OA, CT5lA ONLY)
OIL BURNER CONTROL
BOTTOM MOUNTING HOLE
TEMPERATURE SETTING LEVER