Middleby Marshall PS220, PS570, PS360 3D air finger label if present, Internal air finger chart

	SECTION 2 - AIR FLOW AND HEAT TRANSFER
B. Configuration and Alignment	2. Check that the bake time and temperature settings
To ensure proper baking of the product, the air flow	of the oven match the customer’s specifications.
	Most customers have an acceptable range for bake
MUST be properly aligned as it exits the air fingers.
	time and temperature to allow for local variations in
Because air finger configurations are tested at the fac-
	altitude, humidity, etc.
tory for a specific customer’s product, severe bake prob-
	3. If these checks fail to correct the problem, you
lems related to the air fingers are rare. If you encoun-
	should perform a test bake to pinpoint the type of
ter a problem, check the following:
	baking problem that is present.
1. Check that the air fingers are properly assembled,
	C. Performing a Test Bake
cleaned and free of obstructions. For the standard
air fingers shown in Figure 4, a variety of styles are	Before you attempt to correct any problem, please CON-
available for each of the three components. It is	FIRM THAT THERE IS ACTUALLY A PROBLEM. It is
often possible to assemble these components in-	extremely difficult to tell if an oven is baking unevenly
correctly, as they are designed to be modular. This	by simply looking at a pizza with ingredients, espe-
will affect the quality of the bake.	cially if the pizza is a large combination-type. Often,
If you need information on the correct air finger con-	the ingredients and toppings themselves can cause an
	uneven bake.
figuration of the oven, check the following:

•3D air finger label or card. Many current ov- ens will have a three-dimensional drawing on the front panel of the oven that shows the cor- rect air finger configuration, as shown in Fig- ure 5. Other ovens may have this information on a laminated card attached to the oven.

•Internal air finger chart. All Middleby ovens have a chart similar to the one shown in Figure 6 attached inside the machinery compartment door. Note that if the air finger configuration has been updated since the oven was installed, this chart may no longer be correct.

•If there is no label present on the oven, and the chart inside the machinery compartment is in- correct, contact Middleby Technical Service for assistance.

The best way to check for an uneven bake is to make a test bake with a consistent, “predictable” product and then read it. We recommend using the customer’s dough (for a pizza product) OR a commercially-avail- able pancake mix (for customers with a variety of prod- ucts). The pancake mix is generally more sensitive to variations in temperature and thus provides more accu- rate results than the dough test.

When interpreting the results of the test, consistently uneven baking on the top of the product may indicate a problem with the upper air fingers. Likewise, consis- tently uneven baking on the bottom of the product may indicate a problem with the lower air fingers.

The most common bake problem is a “front-to-back” bake issue. This problem occurs when the “front” of the conveyor belt (towards the window) receives more heat than the rear, or vice-versa. This results in uneven bak- ing for the product based on where it is placed on the conveyor.

	Figure 5	Figure 6
3D air finger label (if present)		Internal air finger chart

NOTE: Labels of this type are not used on all ovens. Label placement and design will vary based on customer preference.

NOTE: All ovens use a chart of this type inside the machinery compartment.

Changes to the air finger configuration after oven installation MAY NOT BE INDICATED.

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