Make sure that the heat anticipator setting on the thermostat is 0.6 amps (or in accordance with the amperage value noted on the wiring diagram of your heater).
Make thermostat connections at the terminal strip on the back of the heater. The strip has four terminals, R, G, W1, and W2; refer to the wiring diagram.
FIGURE 13 - Terminal Strip for
NOTE: The size of heater illustrated has a vertical terminal strip. Some sizes have a horizontal terminal strip.
Rear View - Model UDAP
Terminal 
Strip R
G
W1
W2
Supply
Wiring
Entrance
Rear View - Model UDAS
Terminal 
Strip R
G
W1
W2
Disconnect
Switch
Supply
Wiring
Entrance
Unit Mounted
Thermostat -
Option CM3
Multiple Heater
Control - Option
CL31 and Option
CL32
16.Combustion Air Proving Switch (Pressure Switch)
If the heater was ordered with Option CM3, a kit for mounting the thermostat on the rear of the heater is shipped separately. Follow the instructions in the option package to attach the bracket.
Select a
If the heater was ordered with a multiple heater control option, one thermostat can be used to control up to six heaters. The option includes a 40VA transformer that replaces the standard transformer in the “master” unit and a relay assembly that attaches to the “slave” unit. Option CL31 provides for control of two heaters. If control of additional heaters is desired (up to six total), Option CL32 which is the relay assembly only must be added to each of the “slave” heaters.
The option packages are shipped separately and include complete instructions on installation and wiring.
The combustion air proving switch is a pressure sensitive switch that monitors air pressure to ensure that proper combustion airflow is available. On Model UDAP, the switch is a single pole/normally open device which closes when a negative pressure is sensed in the venter housing. On Model UDAS, the switch senses the differential pressure between the negative pressure in the venter housing and the pressure in the cabinet. (For switch location, see FIGURE 18, page 31.)
On startup when the heater is cold, the sensing pressure is at the most negative level, and as the heater and flue system warm up, the sensing pressure becomes less negative. After the system has reached equilibrium (about 20 minutes), the sensing pressure levels off.
If a restriction or excessive flue length or turns cause the sensing pressure to be outside the switch setpoint, the pressure switch will function to shutoff the main burner. The main burner will remain off until the system has cooled and/or the flue system resistance is reduced.
Form
