Middleby Cooking Systems Group
•
1400 Toastmaster Drive
•
Elgin, IL 60120
•
USA
•
(847) 741-3300
•
FAX (847) 741-4406
Instructions for Service Kit 39733
High Limit Conversion Kit for PS300, 310, 350, & 360 Ovens
KIT COMPONENTS - Check that the kit includes ALL of these parts BEFORE you begin!
Qty.
P/N
Description
Qty.
P/N
Description
1
1
1
1
1
39732
34982
30693
35634
35691
Instructions
2 ft./610mm 27152-0050 Wire, #18 AWG, brown
2 ft./610mm 27152-0053 Wire, #18 AWG, white
2 ft./610mm 27152-0054 Wire, #18 AWG, purple
Watlow high limit control module
Reset switch w/ lighted pushbutton
Mounting bracket, reset switch
Wire set, reset switch (includes 4
wires and 3 1/4”/25mm connectors)
Thermocouple, type J, 6”/152.4mm
Mounting sleeve, thermocouple
8
1
2
2
4
1455A8750 Wire connector, 1/4”/6.4mm
3002693
2000076
Wire tie, nylon
Screw, 6-32 X 1-5/8”
1
1
33812-1
39690
1421B8803 Screw, 6-32 X 1/4”
2001327 Nut, 6-32
TOOLS REQUIRED
Figure 1
•
•
Drill with 3/16” drill bit
Middleby Marshall Thermocouple Signal Source
Generator (P/N 27170-0192)
Wire cutters/strippers
United Electric Type 54
High Limit Control
•
A. OVERVIEW
This Service Kit is used to replace two different types of
United Electric high limit/cooldown controllers with a
Watlow high limit controller for PS300, 310, 350, and
360 Ovens. See Figure 1.
•
The early (Type 54) United Electric control was ONLY
equipped with a high limit circuit. Ovens equipped
with this control did NOT have a cooldown circuit.
This control was used on the following models:
United Electric Type 55
High Limit/Cooldown
Control
-
-
PS300/350 Gas (early)
PS300/310/350/360 Electric (early - all voltages)
For these ovens, the kit directly replaces the Type
54 high limit control with the Watlow high limit con-
trol.
•
The later (Type 55) United Electric control was
equipped with BOTH high limit and cooldown circuits,
and was used on the following models:
-
PS300/310/350/360 Electric (late), 208/240V and
480V UL versions ONLY
Lighted Reset
Switch
For these ovens, the kit replaces the Type 55 con-
trol with the Watlow high limit control, and uses the
oven’s temperature controller to provide the
cooldown circuit.
Watlow High
Limit Control
P/N 39732
Page 1 of 8
Rev. B • V1 • 5/99
Figure 2
High limit thermocouple location -
lower oven
High limit thermocouple location -
upper oven
Figure 3
Figure 4
NOT TO SCALE
Figure 5
Figure 6
Thermocouple
Base
Sleeve
Hole in sleeve is
next to base of
thermocouple
Page 3 of 8
C. WIRING
For the various wiring connections listed below, cut the kit-supplied #18 AWG wires to length. Refer to
Figures 7 and 8 (on pages 6 and 7) for diagrams of the wiring connections.
Lighted Reset Switch Wiring and Installation
14. Using the kit-supplied 1/4” wire connectors, connect the following kit-supplied wires:
-
-
-
Red wires ................. connect one wire to each “RESET” terminal on the high limit control
Black wire ................. connect to terminal “NC” on the high limit control
White wire................. connect to terminal “L2” on the oven’s temperature controller
15. Slip the free ends of these four wires through the circular hole in the reset switch mounting bracket, so
that they hang down in front of the control compartment.
16. Use the kit-supplied 1/4” wire connectors to connect these four wires to the terminals on the lighted
reset switch.
-
-
-
Terminals 1 and 3..... Red wires (these connections are interchangeable)
Terminal 2 ................ Black wire
Terminal 4 ................ White wire (kit-supplied)
17. Push the lighted reset switch through the mounting hole in the center of the bracket until it snaps into
place. Be sure to avoid pinching the wires against the sides of the mounting hole.
Cooldown circuit wiring
NOTE: Perform steps 18 and 19 ONLY if you are replacing a UE Type 55 controller. If you are
replacing a UE Type 54 controller (which has no cooldown circuit), skip ahead to Step 20.
18. Attach the oven’s existing cooldown wiring to the following terminals on the oven’s Temperature Con-
troller, as shown in Figures 7 and 8.
For Ovens with a Digital Temperature Controller:
a. Terminal 9 ................ Black wire (from blower switch)
b. Terminal 10 .............. Brown wire (from blower switch)
For Ovens with an Analog Temperature Controller:
a. Terminal 13 .............. Black wire (from blower switch)
b. Terminal 14 .............. Brown wire (from blower switch)
19. Attach a brown kit-supplied wire between the following terminals on the Temperature Controller:
Digital Controller ............. Terminals 10 and “L1”
Analog Controller............ Terminals 13 and “L1”
High Limit Control wiring
20. Using the kit-supplied 1/4” wire connectors, wire the high limit control terminals as follows:
a. Terminal “NO”........... Purple wire (originally to UE control)
c. Terminal “TC +” ........ White wire (to thermocouple) - DO NOT CUT THIS WIRE TO LENGTH.
d. Terminal “TC -” ......... Red wire (to thermocouple) - DO NOT CUT THIS WIRE TO LENGTH.
f. Terminal “L2” ............ White wire (kit-supplied; to neutral on the oven’s terminal block)
h. Terminal “COM”........ Orange wire (originally to UE control)
21. Using a 1/4” wire connector, attach a brown kit-supplied wire to the “L1” terminal on the high limit
control. Attach the free end of the wire to the “L1” terminal on the temperature controller.
Page 4 of 8
D. TESTING THE INSTALLATION
22. Remove the thermocouple wires from the “TC +” and “TC -” terminals on the high limit control.
23. Attach a Middleby Marshall Thermocouple Source (P/N 27170-0263) to the “TC +” and “TC -” termi-
nals on the high limit control, in place of the thermocouple wires. Note that it may be necessary to
attach a pair of terminal connectors to the leads of the Thermocouple Source to allow them to connect
to the high limit control’s terminals.
24. Restore the gas supply (if so equipped) and the electrical supply to the oven. Because the control
compartment door is still open, pull the door safety switch out into the “service” position.
25. Test the operation of the high limit control as follows:
a. Set the Thermocouple Source to a normal operating temperature, between 200°-600°F (93°-315°C).
b. Turn the oven on, and allow it to heat to 600°F (315°C).
c. After the oven has reached the setpoint temperature, set the Thermocouple Source to 700°F (371°C).
The high limit control is set to open at any temperature in excess of 650°F (343°C). This will shut
down the oven’s heat circuit and illuminate the Reset Switch lamp.
26. Set the Thermocouple Source to a temperature setting below 600°F (316°C), and depress the Reset
Switch. This should turn off the Reset Switch lamp and restore heat circuit operation.
27. Turn the oven off.
28. If you replaced a UE type 55 controller (with a cooldown circuit), you must set the Thermocouple
Source to a temperature setting below 200°F (93°C). Then, wait for the blowers to turn off.
29. Press the door safety switch in to reset it to normal.
30. Remove the Thermocouple Source from the oven.
31. Reattach the thermocouple wires to the high limit control’s terminals as follows:
White wire ................ “TC +”
Red wire ................... “TC -”
32. Close the machinery compartment and control compartment access panels, and fasten them in place.
The oven is now ready for normal operation.
Page 5 of 8
Figure 7 - United Electric Model 55 replacement: ovens with a cooldown feature
KEY
Figure 8 - United Electric Model 54 replacement: ovens without a cooldown feature
KEY
A MIDDLEBY COMPANY
Middleby Cooking Systems Group • 1400 Toastmaster Drive • Elgin, IL 60120 • USA • (847) 741-3300 • FAX (847) 741-4406
Middleby Corporation Service Hotline 1-800-238-8444
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