Mr. Heater HS25NG/LP Operating Instructions And Owner's Manual page 13

Below in chart form are various symptoms of a malfunctioning system, possible defects that will cause these symp-
toms and suggested corrective measures. The chart assumes that the proper gas pressure is available to the heater
and that the lighting procedure is as stated on the plate attached to the heater.
SYMPTOMS
burner light off very slow
burner light off very slow infra-red
color stays dull
burner flash back
(roaring noise during operation
dark)
ceramic grid or burner sooting up
(when new or after cleaning)
pilot cannot be ignited
pilot lights but goes out
pilot stays lit but main burner
will not light
failure to ignite
3. REPLACING THE GAS VALVE UNIT
A. Remove the two gas valve unit wires at the gas
control valve labeled "PP".
B. Unscrew gas valve from gas piping.
C. Reconnect gas valve and unit wires to terminals
"PP". Be sure to leave thermostat wire on one
terminal.
4. FREQUENCY OF OPERATOR CHECKS
Intermittent use. Appliances that are used seasonally
should be checked before shutdown and again before
the next use.
Model # MH25NG/LP
Table 4. Trouble Shooting Chart
CAUSES
partially block pilot orifice
pilot out of adjustment
partially blocked burner orifice
low gas pressure
damaged burner
first check for damaged burner
orifice
if burner orifice is not damaged
then check for damaged manifold
blocked pilot orifice
gas cock not in position
pilot gas flow adjustment
screw may be closed
defective thermocouple
defective control
loose wire or improperly wired
defective control
blocked burner orifice
main gas off
air in gas line
loose wire connections
dirty wire connections
HS25NG/LP
SOLUTIONS
replace
re-adjust pilot
replace
call your gas supplier
and ceramic grid surface will be
replace
replace if damaged
replace
replace
gas cock knob must be
turned to pilot and held
depressed
open and adjust
(see Figure 12)
replace
replace
tighten connections, check
wiring diagram
replace
clean orifice or replace
open manual valves
bleed gas line
tighten wire connections
clean terminals and secure
terminals
Dusty, wet or corrosive environment. Since these
environments can cause the gas control to deteriorate
more rapidly, the system should be checked more often.
The gas control should be replaced if:
A. It does not perform properly on checkout or trouble
shooting.
B. The gas control knob Is hard to turn or push down,
or it fails to pop back up when released.
Installation instructions and Owner's Manual
E13