MARSAL MB236, Service Manual, Page: 3 / 9

2
1. If thermostat is in a runaway condition and will not shut off at set temperature, replace
the thermostat.
2. If thermostat will not maintain calibration after adjustment, replace thermostat.
3. If thermostat bulb or capillary are cut, bent, or unnecessarily flattened, replace
thermostat.
(This is NOT covered under the warranty!)
MAINTENANCE INSTRUCTIONS
ADJUSTMENTS
Many malfunctions attributed to defective material or faulty workmanship may be rectified by the
adjustment of pilot burners, main burners, or thermostats. It is therefore wise to attempt to correct
operational difficulties
through adjustment rather than the immediate replacement of parts .
PILOT BURNER ADJUSTMENT #70101
A commonly diagnosed malfunction of the safety pilot valve is the pilot burner/flame sensing bulb
relationship resulting from:

Improper draft

Low gas pressure. (Natural Gas 4.5”WC – Propane Gas 11”WC)
 Clogged pilot burner orifice from dirt and debris from unpurged gas lines.
 Incorrect adjustment of pilot burner flame.
When working correctly, the flame must engulf the safety pilot probe tip
Figure 2