tekmar 518 Thermostat Installation - Manual (Page 6)

© 2013 518_D - 03/13
6 of 12 A Watts Water Technologies Company
Switching Relay ----------------------------------------------------- -----------------------------------------------------
Testing the Thermostat Wiring
Testing the Power --------------------------------------------------- ---------------------------------------------------
If the thermostat display turns on, this indicates that the thermostat is operating correctly
and there are no electrical issues. In the event that the display is permanently off:
1. Remove the thermostat front.
2. Use an electrical meter to measure voltage between the R and C wiring terminals.
For AC power supplies the voltage should measure between 10 to 30 V (ac). For
DC power supplies the voltage should measure between 10 to 30 V (dc).
3. If the voltage on the R and C wire terminations is continuous and the thermostat
display is not on, the thermostat may have a fault. Contact your tekmar sales
representative for assistance.
If the thermostat display intially powers on but later shuts off intermittantly, there
may be a short circuit from the W wire to ground, or the power supply is too small to
power the load.
Testing the Heat Zone Output Wiring ---------------------------------- ----------------------------------
1. Touch the button and set the heating temperature above the current room
temperature. Make sure the display does not flash “Max” if using a floor sensor.
2. When the “Heat On” symbol appears on the display, use an electrical meter to check
for voltage on the W and C wires connected to the zone valve, wiring center, relay
or switching relay. The electrical meter should read 10 to 30 V (ac) or (dc).
3. If the W and C wire have voltage, check the zone valve, wiring center, relay or pump
to determine if the heat device is operating correctly.
Thermostat Wiring
C 518 R Rh W1 S1 Com
No Power
R W
24 V
R W
H N X X H N H N N H
Com Switching Relay
Zone 1 Zone 2 Zone 3
Class 2
Transformer
R W
Zone 1 Zone 2 Zone 3
C 518 R Rh W1 S1 Com
No Power
Optional
Slab Sensor 079
L N
Pump