Mr. Heater MH25LP - Manual (Page 13)

E13 Installation instructions and Owner’s Manual Model # MH25NG/LP HS25NG/LP
Table 4. Trouble Shooting Chart
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 CAUSES SOLUTIONS
burner light off very slow partially block pilot orifice replace
pilot out of adjustment re-adjust pilot
burner light off very slow infra-red partially blocked burner orifice replace
color stays dull
burner flash back low gas pressure call your gas supplier
(roaring noise during operation and ceramic grid surface will be
dark) damaged burner replace
ceramic grid or burner sooting up first check for damaged burner replace if damaged
(when new or after cleaning) orifice
if burner orifice is not damaged replace
then check for damaged manifold
pilot cannot be ignited blocked pilot orifice replace
gas cock not in position gas cock knob must be
turned to pilot and held
depressed
pilot gas flow adjustment open and adjust
screw may be closed (see Figure 12)
pilot lights but goes out defective thermocouple replace
defective control replace
pilot stays lit but main burner loose wire or improperly wired tighten connections, check
will not light wiring diagram
defective control replace
blocked burner orifice clean orifice or replace
failure to ignite main gas off open manual valves
air in gas line bleed gas line
loose wire connections tighten wire connections
dirty wire connections clean terminals and secure
terminals
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.
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.