Desa CD42M-A2 - Manual (Page 17)

www.desatech.com 111916-01F 17
TROUBLESHOOTING
WARNING: Turn off heater and let cool before servicing. Only a
qualified service person should service and repair heater.
WARNING: Turn off heater and let cool before servicing. Only a
qualified service person should service and repair heater.
OBSERVED PROBLEM
Pilot will not stay lit
Pilot lit but no flame on burner
Frequent pilot outage
POSSIBLE CAUSE
1. Defective thermocouple
1. Remote or wires defective
2. Thermopile not generating
sufficient milivoltage
3. Plugged burner orifice
1. Pilot flame may be too low
or blowing (high) causing
safety pilot to “drop out”
REMEDY
1. Check pilot flame. It must
impinge on thermocouple
2. Clean or adjust pilot for maxi-
mum flame impingement on
thermocouple
3. Ensure the connection be-
tween valve and thermocouple
are tight and secure
4. Check thermocouple with
millivolt meter. Take reading
at thermocouple terminals of
gas valve with remote control
off. It should read 18 millivolts
minimum. Replace faulty ther-
mocouple if reading is below
specified minimum
1. Check remote wires for proper
connections. Place jumper
wire across terminals at re-
mote control. If burner comes
on, replace remote. If okay,
place jumper wire across
remote control at valve. If
burner comes on, wires are
faulty or connections are bad
2. Check thermopile with mil-
livolt meter. Take reading at
thermopile terminals of gas
valve with remote control off.
It should read 325 millivolts
minimum. Replace thermopile
if reading is below specified
minimum
3. Check burner orifice for stop-
page and remove
1. Clean and/or adjust pilot flame
for maximum flame impinge-
ment on thermocouple