Replacing The Gas Valve Unit; Frequency Of Operator Checks - Mr. Heater MH25NG Mode D'emploi

Below in chart form are various symptoms of a malfunctioning system, possible defects that will cause these symptoms
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)
Ceramic grid burner sooting
(when new or after cleaning)
Pilot can not 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.
Mr. Heater / Infrared Workshop Heater
Table 4. Trouble Shooting Chart
CAUSES
- Partially block pilot orfice
- Pilot out of adjustment
- Partially block burner orifice
- Low gas pressure
- Damaged burner
- First check for damaged burner orifice
- If burner orifice is not damaged then
check for damaged manifold
-Block 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
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
SOLUTIONS
- Replace
- Re-adjust pilot
- Clean or Replace
- Call your gas supplier:
Ceramic grid surface will need to be
replaced
- Replace if damaged
- Replace
-Replace
- Gas cock knob must be turned to pilot,
depressed and held down.
- 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 and Secure terminals