Marsal & Sons 4 Pie Combo, MB-SD User Manual

OVEN SERVICE MANUAL

MB42, MB60, MB236, MB260, SD236, SD248, SD 260, SD448, SD660,

SD1048, SD1060, 4 Pie Combo, 6 Pie Combo

RETAIN THIS MANUAL FOR FUTURE REFERENCE

© Marsal & Sons, Inc. 175 E. Homan Ave. Lindenhurst, NY 11757 [phone] www.marsalsons.com

TESTING OF COMPONENTS

AUTOMATIC SAFETY PILOT VALVE (TSII) #SV105

Pilot gas is supplied from the main valve inlet through a
drilled passageway to the pilot burner. Pushing the red reset
button temporarily allows gas to ow to the pilot burner for
ignition of the pilot burner ame. When the bulb heats to a
cherry red glow, the main valve opens to allow gas to ow
to the main burner. The red reset button is then released.

If the pilot burner ame fails and cannot be reactivated the
following test can be performed:

•

Pilot Burner Adjustment: Refer to section on Page 3

•

Clean Pilot burner’s limiting orice as follows:

1. Disconnect gas tubing at the pilot burner body.

2. Remove cup shaped orice from pilot burner
body.

3. Clean orice by blowing any foreign matter out
the orice hole. Take care not to enlarge orice
hole.

4. Replace components in reverse order. If the pilot
burner still does not operate or the main burner
comes with a low ame, or will not come at all,
replace the Automatic Safety Pilot Valve (TSII)

manual control
valve #M125

pressure
regulator
#RVL8-N (or) P

safety valve
#SV105

thermocouple
#TE48

manual control
valve #M125

pressure tap

MAIN MANUAL CONTROL VALVE #M125

thermostat
#G140

The main manual control valve is a simple bull valve. Due
to its simplicity, failures of this type of valve are practically
non-existent. For diculties associated with this control, it
would be best to replace the valve.

OVEN CONTROLS

(FIGURE 1)

THERMOSTAT FDTH #G140

For any suspected thermostat problems the following procedures should be reviewed in this manual:

•

Thermostat adjustment.

•

Bypass (Minimum Burner Flame) adjustment.

•

Thermostat calibration. Most thermostat failures will generally fall into one of the following three categories:

1. If thermostat is in a runaway condition and will not shut o at set temperature, replace the
thermostat.

2. If thermostat will not maintain calibration after adustment, replace thermostat.

3. If thermostat bulb or capillary are cut, bent, or unnecessarily attened, replace thermostat.

MAINTENANCE INSTRUCTIONS

ADJUSTMENTS

Many malfunctions attributed to defective material or faulty workmanship may be rectied by the adjustment of
pilot burners, main burners, or thermostats. It is therefore wise to attempt to correct operational diculties through
adjustment rather than the immediate replacement of parts.

Pilot Burner Adjustment #M111

A commonly diagonsed malfuction of the safety pilot valve is the pilot burner/ame sensing bulb relationship
resulting from:

•

Low gas pressure.

•

Clogged pilot burner orice from dirt and debris from unpurged gas lines.

•

Incorrect adjustment of pilot burner ame.

•

Flame sensing bulb not positioned in hottest part of pilot burner ame. Highest ame temperatures

occur at a point just above the outer ame cone.

To make this adjustment, proceed as follows:

1. Loosen screw that holds the safety pilot probe to the bracket and adjust the bulb so that it is in the ame
properly.

2.

Insert a small screwdriver just below the red button of the safety valve.

3. Turn adjusting screw until the size of ame is as desired.

4. The ame must engulf the safety tip.

pilot hood

safety pilot probe

PILOT BURNER

(FIGURE 2)

MAIN BURNER ADJUSTMENTS

Satisfactory oven performance and burner life are dependent on correct burner adjustment. Before shipment, burners have been
adjusted for proper operation with the type specied on the rating plate which is located inside the control compartment above

the light switch. If further adjustment is necessary proceed as follows:

Adjust primary air shutter at the front of the burner compartment to obtain a stable and quiet ame.

•

If too much primary air is prsent, ames will lift from the burner prts. A reduction in primary air will correct this condition.

•

Too little primary air will cause yellow tipping or an entire yellow ame to appear. This condition indicates incomplete

•

combustion and may cause carbon sooting to appear on metal parts near the ame.

When a ame raises o the burner it is important to determine if it is a “lifting ame” or a “oating ame”:

•

•

”Lifting Flames” rise from the ports to burn some distance above the ports. In some cases these ames will drop back
to the port and lift again intermittently. They are caused by too much primary air. Decreasing the shutter opening will
stop lifting ames.

•

”Floating Flames” are long and lazy looking, poorly dened, quiet ames which roll around the combustion chamber
sometimes completely o the ports. Floating ames result from too little secondary or “make up” air. Lack of secondary
air can be caused by incorrect venting, clogged ueways, blocked secondary air inlet openings, or lack of natural room
makeup air to the oven.