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.
 
 
 Thermocouple
Turn off gas supply. Remove thermocouple
from 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
very tip of thermocouple (end removed
from valve). Clip red lead to the outer casing
of thermocouple for ground. Relight
unit output should be between 18 and 28
millivolts.
 
Relay
Turn off gas supply. Remove bottom of
base (if equipped). Relay is a normally
open circuit between terminals 4 and 6
which closes when current is supplied.
Using a digital multi-meter measure the
resistance. With no power to unit, resistance
between terminals 4 and 6 is open
circuit or no resistance. Apply power to
relay. Resistance between terminals 4 and
6 should be less than 100 mili ohms.
 
Courtesy DESA