Middleby Marshall P/N 60250 Connection, Gas Conversion, PS740 Propane Conversion

B. Connection

Check the oven’s gas supply requirements before making the gas utility connection. Gas supply requirement are listed on the oven’s serial plate and in Table 1-4. Gas Orifice and Pressure Specifications (in Section 1, Description).

Check the serial plate to determine the type of gas (Propane or Natural) to be used with the oven.

Refer to the instructions in the gas hose package (included in the Installation Kit) before connecting the gas line. One gas line connection method is shown in Figure 2-18; however, compliance with the applicable standards and regula- tions is mandatory.

Inlet, regulated, and pilot gas pressure readings can be taken using a digital tube manometer at the tap location shown in Figure 2-19. Figure 2-19 shows the burner assembly and Figure 2-21 shows the gas valve.

NOTE: The installation must conform with local codes or in the absence of local codes, with the National Fuel Gas Code, ANSI Z223.1-latest edition.

Certain safety code requirements exist for the installation of gas ovens; refer to the beginning of Section 2 for a list of the installation standards. In addition, because the oven is equipped with casters, the gas line connection shall be made with a connector that complies with the Standard for Connectors for Movable Gas Appliances, ANSI Z21.69 (in U.S.A.), as well as a quick-disconnect device that complies with the Standard for Quick-Disconnect Devices for Use With Gas Fuel, ANSI Z21.41 (in U.S.A.).

C.Gas Conversion

Where permitted by local and national codes, it is possible to convert ovens from natural to propane gas, or from propane to natural gas. Use the appropriate Middleby Gas Conversion Kit for the specific oven model.

CAUTION: The terms of the oven’s warranty require all

start-ups, conversions and service work to be performed by a Middleby Authorized Service Agent.

D.PS740 Propane Conversion

Two items have to be changed, to change the oven to LP:

1.Replace main orifices.

2.Adjust main gas regulator per instructions below.

Disconnect the manifold union closest to the main burner, and remove the manifold assembly (four screws). Slide out the manifold assembly (leaving the ignition and sense wires con- nected). Replace the main orifices.

Replace the main orifices on the manifold assemblies with the LP units, and replace the manifold assembly. Reconnect the union.

E.Adjusting the Maximum Pressure Setting

1.Disconnect pressure feedback connection (if applicable).

2.Connect a suitable pressure gauge to pipe line or to outlet pressure tap of gas control concerned, to measure burner pressure (measuring point must be as near to burner as possible).

Figure 2-18. Flexible Gas Hose Installation

1/2″ gas	3/4″-1/2″
pipe nipple
	gas pipe	To Gas
	reducer
		Supply
		Pipe
	3/4″ gas
	pipe nipple
1/2″ gas
line tee with	90°
pressure tap
	Elbow

Full-Flow

Gas

Shutoff

Valve

	Flexible	Individual gas
Quick-		connection
	Gas Hose
		for each oven
disconnect
		cavity
device

Figure 2-19. Gas Burner Assembly

Gas Burner

Manifold Pressure Tap

3.Make sure that the appliance is in operation and the Mo- duplus® coil is energized with maximum current.

4.If maximum rate pressure needs adjustment, use an 8 mm wrench to turn adjustment screw for maximum pres- sure setting (clockwise to increase or counter-clockwise to decrease pressure), until the desired maximum outlet pressure is obtained.

5.Disconnect electrical connection of the Moduplus®.

6.Check minimum pressure setting and readjust if neces- sary. (See Adjusting Minimum Pressure Setting for proper adjusting procedure.)

7.Reconnect pressure feedback connection (if applicable).

8.If minimum and maximum pressures are set, wire the

Moduplus® in circuit.

9.Close pressure tap screw.

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