Test a Thermocouple
The heater will run as long as the control valve is pressed. According to DESA test these parts. NOTE: Not all heaters are equipped with a relay.
Turn off the gas supply. Remove thermocouple
from the gas valve. Using a digital
multi-meter set to the lowest DC millivolt
setting (meter needs to have alligator clips
on ends of leads), clip black lead to the
the very tip of the thermocouple (end removed
from valve). Clip red lead to the outer casing
of thermocouple for ground. Relight
the unit output should be between 18 and 28
Turn off the gas supply. Remove the bottom of
the base (if equipped). Relay is a normally
open circuit between terminals 4 and 6
which closes when the current is supplied.
Using a digital multi-meter measure the
resistance. With no power to the unit, the resistance
between terminals 4 and 6 is open
circuit or no resistance. Apply power to
relay. The resistance between terminals 4 and
6 should be less than 100 million ohms.