Middleby Marshall PS555 Midco burner, Wayne burner, C. Component Identification, Burner type

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.

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:

-	PS200-series	-	PS360WB
	(through 3/02)	-	PS360WB70
-	PS310	-	PS570S
-	PS314		(through 8/00)

-PS360

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	-	PS570S
	(4/02 or later)		(9/00 or later)
-	PS360EWB	-	PS570G

-PS555

Additional information on the modulating valve is provided in Modulating Valve on Page 97.

Figure 61 - Midco burner	Figure 62 - Wayne burner
Burner blower	PS360EWB shown. For different oven models, refer
	to the drawings on pages 88-90.

Air

shutterPlenum Burner Air shutter blower

Main gas

line

Main gas	Burner
	blower
line
	motor

	Plenum
		Burner
	Pilot line	blower
Pilot line		motor

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