Replacing The Gas Valve Unit; Frequency Of Operator Checks - Mr. Heater MH40NG Guide D'utilisation Et Instructions De Fonctionnement

tip­of­the­thermocouple­or­generator.­To­adjust­the­pilot­flame,­
refer­to­Figure­7.
a.­­ Remove­pilot­adjustment­cover­screw.­Refer­to­Figure­8.
b.­­ Turn­inner­adjustment­screw­clockwise­to­decrease­or­counter-
clockwise to increase pilot flame.
c.­­ Always­replace­cover­screw­after­adjustment­and­tighten­firmly­
to ensure proper operation.
Pressure regulator
adjustment­(beneath­
Manual gas
cover­screw)
control knob
Wrench­
boss
Gas
inlet
Pilotstat Pilot flow adjusting screw
(beneath­cover­screw)
power unit
Figure 8. Top view of standard capacity gas control.
TABLE 4. TROUBLESHOOTING CHART
Below­in­chart­form­are­various­symptoms­of­a­malfunctioning­
system, possible defects that will cause there symptoms and
suggested­corrective­measure.­The­chart­assumes­that­the­proper­
SYMPTOMS
Burner­light­off­very­slow­
Burner­light­off­very­slowly­
Color­stays­dull­
Burner­flashback­
(roaring­noise­during­operation­­
and­ceramic­grid­surface­will­be­dark)­
Ceramic­grid­or­burner­sooting­up­
(when­new­or­after­cleaning)­
­
Pilot­cannot­be­ignited­
­
Pilot­lights­but­goes­out­
­
Pilot­stays­lit­but­main­burner­will­not­light­
­
­
­
Failure­to­ignite­
­
­
­
Install­long­
screw in
outside corner
Standard­
pressure
regulator
("A"­model)
Step­
opening
Pilot gas
regulator
outlet
("C"­model)
(pressure­
tapping
directly
beneath)
CAUSES
Partially­blocked­pilot­orifice­
Pilot out of adjustment
Partially­blocked­burner­orifice­
­
Low­gas­pressure­
­
Damaged­burner­
First­check­for­damaged­­
burner orifice
If­burner­orifice­is­not­damaged­
then check for damaged manifold.
Blocked­pilot­orifice­
Gas cock not in position
Pilot gas flow adjustment screw may be closed
­
Defective­thermocouple­
Defective­control­
Loose­wire­or­improperly­wired­
Defective­control­
Blocked­burner­orifice­
­
Main­gas­off­
Air­in­gas­line­
Loose­wire­connections­
Dirty­wire­connections­
Model # MH40NG/LP

13. REPLACING THE GAS VALVE UNIT

a.­­ Remove­the­two­gas­valve­unit­wires­at­the­gas­control­valve­
labeled­"PP."
b.­­ Unscrew­gas­valve­from­gas­piping.
c.­­ Reconnect­gas­valve­and­unit­wires­to­terminals­"PP."­Be­sure­
to­leave­thermostat­wire­on­one­terminal.

14. FREQUENCY OF OPERATOR CHECKS

Intermittent Use
Appliances­that­are­used­seasonally­should­be­checked­before­
shutdown­and­again­before­the­next­use.
Dusty,­wet­or­corrosive­environment.­Since­these­environments­
can cause the gas control to deteriorate more rapidly, the system
should be checked more often.
The gas control should be replaced if:
a.­­ It­does­not­perform­properly­on­checkout­or­troubleshooting.
b.­­ The­gas­control­knob­is­hard­to­turn­or­push­down,­or­it­fails­
to pop back up when released.
gas­pressure­is­available­to­the­heater­and­that­the­lighting­
procedure is as stated on the plate attached to the heater.
SOLUTIONS
Re-adjust­pilot
Replace
Replace
Correct­line­pressure­or­call­your­gas
supplier
Replace
Replace­if­damaged
Replace
Replace
Gas control knob must be turned to pilot
and held depressed
Open­and­adjust­(see­Figure­8)
Replace
Replace
Tighten­connections,­check­wiring
diagram
Replace­
Clean­orifice­or­replace
Open­manual­valves
Bleed­gas­line
Tighten­wire­connections
Clean­terminals­and­secure­terminals
6
Installation Instructions and Owner's Manual