Middleby Marshall PS200 series - Manual (Page 93)

92
SECTION 3 - SERVICING COMPONENTS
C. Component Identification
1. Burner type
Middleby ovens are equipped with one of two main burner
designs. Details of these burners are provided below.
1. Midco burner - see Figure 61. This burner was
used on PS360WB70 and PS360EWB ovens only.
Late-production PS360EWB and PS360WB70 ov-
ens used the Wayne burner shown in Figure 62. In
addition, many PS360EWB ovens were retrofitted
during 1998 to use the Wayne burner.
Servicing the Midco burner is beyond the scope of
this manual. However, note that most gas train
components EXCEPT FOR THE BURNER ITSELF
are identical to the components used with the
Wayne burner. If necessary, contact Middleby Tech-
nical Service for assistance.
2. Wayne burner - see Figure 62. Wayne burners are
used on all Middleby oven models except early-
production PS360WB70 and PS360EWB models.
The Wayne burner configuration varies slightly be-
tween oven models and so may be slightly differ-
ent from that shown in Figure 62. Refer to the
drawings in Part Number Reference - Burner Com-
ponents (pages 88-90) for illustrations of the burner
configuration used on each oven model. Common
variants include:
•
Flexible air tube between the burner blower and
plenum. Used on all PS555/570 series ovens.
• 120V burner blower motor. Used on PS200-
series (through 3/02), PS310, PS314, PS360,
PS360WB and PS570S ovens.
• 208/240V line voltage blower motor. Used on
PS200-series (4/02 or later), PS360WB70,
PS360EWB, PS555, and PS570G ovens.
Figure 61 - Midco burner Figure 62 - Wayne burner
PS360EWB shown. For different oven models, refer
to the drawings on pages 88-90.
Burner
blower
motor
Air
shutter
Pilot line
Plenum
Main gas
line
Air shutter
Burner blower
Burner
blower
Burner
blower
motor
Pilot line
Plenum
Main gas
line
1. Solenoid valve vs. Modulating valve
Middleby ovens use one of the following systems for
gas flow regulation:
•
On-Off gas flow regulation. These ovens are
equipped with a high flame solenoid valve. The
solenoid valve can only be positioned fully open
(100% gas flow) or fully closed (0% gas flow) as
necessary to maintain the set point. A bypass line
supplies gas to maintain the flame when the valve
is closed. On/off gas systems have a temperature
“swing” of several degrees on either side of the set
point.
On-Off gas flow regulation is used on the following
Middleby oven models:
- PS360WB
- PS360WB70
- PS570S
(through 8/00)
Additional information on the solenoid valve is pro-
vided in Solenoid Valve on Page 96.
• Modulated gas regulation. These ovens are
equipped with a modulating gas valve. The modu-
lating valve can open or close at any setting from 0-
100% gas flow in response to the need for heat to
maintain the set point. Because of this flexibility,
the temperature “swing” is eliminated.
The modulated gas system is used on the following
Middleby oven models:
- PS200-series
(through 3/02)
- PS310
- PS314
- PS360
- PS200-series
(4/02 or later)
- PS360EWB
- PS555
- PS570S
(9/00 or later)
- PS570G
Additional information on the modulating valve is
provided in Modulating Valve on Page 97.