1. Introduction
The Robertshaw 8145-20 Defrost Timer is designed for reliable automatic defrost control in commercial freezers and refrigerators. This device accommodates various defrost systems, including electric defrost heaters, hot gas, and compressor off-cycle methods. This manual provides essential information for the safe installation, operation, and maintenance of your defrost timer.
2. Safety Information
CAUTION: RISK OF ELECTRIC SHOCK
- Always disconnect all power at the main panel before removing the insulator or servicing the device.
- More than one disconnect switch may be required to de-energize the device completely for servicing.
- Ensure the insulator is replaced after wiring is complete.
- Use copper conductors only for all wiring connections.
Failure to follow these instructions may result in electrical shock, fire, or serious injury.
3. Installation and Wiring
This section outlines the general steps for installing and wiring the Robertshaw 8145-20 Defrost Timer. Refer to the wiring diagram on the product label for specific connection details.
3.1 Wiring Connections
The timer is designed for 120V operation. Ensure all connections are secure and comply with local electrical codes.
- Supply Connections: Use wire gauges suitable for 75°C (167°F). Refer to the table below for minimum wire gauge and maximum load ratings.
| Min. Gage Wire | Max Load |
|---|---|
| 8 AWG | 40A |
| 10 AWG | 30A |
| 12 AWG | 20A |
| 14 AWG | 10A |
3.2 Setting Start Pins
Place the start pins in the outer (24-hour) dial at the desired time of day when the switch contacts are to reverse. Ensure that the dial pins are opposite the time pointer for correct operation.
CAUTION: Leave at least one hole between each adjacent pin on the dial.
Image 1: Robertshaw 8145-20 Defrost Timer with the cover open, revealing the internal 24-hour dial, 2-hour dial, and the wiring diagram on the inside of the cover. The image shows the terminal connections for L1, L2, N, and load connections.
4. Operating Instructions
4.1 Setting Back-Up Defrost Termination
To set the back-up defrost termination time, push down and rotate the pointer on the inside (2-hour) dial until it aligns with the desired termination time.
4.2 Setting Time of Day
To set the current time of day:
- Grasp the knob located in the center of the inner (2-hour) dial.
- Rotate the knob in a counter-clockwise direction. This action will cause the outer (24-hour) dial to revolve.
- Align the correct time of day on the outer dial with the time pointer.
- Important: Do not attempt to set the time control by grasping the outer dial. Only rotate the inner dial.
5. Maintenance
Regular maintenance ensures the longevity and proper functioning of your defrost timer.
5.1 Removing the Movement from the Case
To remove the timer movement from its case, locate the spring clip at the right center of the case. Press this clip and lift the movement out.
5.2 Replacing the Movement in the Case
To replace the timer movement, insert the tabs on the left side of the time switch plate into the corresponding holes in the side of the case. Then, push down and snap the movement into place until it is secure.
5.3 Replacement Parts
For replacement of this control, contact your refrigerator manufacturer or a certified Robertshaw dealer.
6. Troubleshooting
If the defrost timer is not functioning as expected, consider the following common issues:
- Timer Not Advancing: Check for proper power supply to the timing motor (208-240V 60Hz). Ensure the inner dial is not obstructed.
- Incorrect Defrost Cycles: Verify that the start pins are correctly placed on the 24-hour dial and that there is at least one hole between adjacent pins.
- No Defrost Activation: Confirm that the wiring connections are secure and that the load is correctly connected to the N.O. (Normally Open) or N.C. (Normally Closed) terminals as required by your system.
- Defrost Cycle Too Long/Short: Adjust the 2-hour dial for back-up defrost termination as needed.
If issues persist after checking these points, contact customer support or a qualified technician.
7. Specifications
| Feature | Detail |
|---|---|
| Brand | Robertshaw |
| Model Number | 8145-20 |
| Product Type | Defrost Timer |
| Voltage | 120V (as per product title, though OCR shows 208-240V for motor/contact rating, user should verify specific model variant) |
| Switch Type | SPDT (Single Pole Double Throw) |
| Material | Steel |
| Colour | Grey |
| Product Dimensions (D x W x H) | 76.2D x 20.3W x 15.2H centimetres |
| Item Weight | 227 g |
| Number of Settings | 2 (24-hour dial, 2-hour dial) |
| Included Components | Defrost Timer |
| UPC | 662013124106, 696335176727 |
| Maximum Contact Rating (Non-Inductive) | 40A, 208-240 Vac |
| Maximum Contact Rating (HP) | 2 hp, 208-240 Vac |
| Maximum Contact Rating (Pilot Duty) | 690 VA, 208-240 Vac |
| Timing Motor | 208-240V 60 Hz |
8. Warranty Information
For specific warranty details regarding your Robertshaw 8145-20 Defrost Timer, please refer to the documentation provided with your purchase or contact Robertshaw customer service directly. Warranty terms typically cover manufacturing defects for a specified period from the date of purchase.
9. Customer Support
If you require further assistance, have questions about installation, operation, or need to order replacement parts, please contact Robertshaw customer service:
- USA Customer Service: 800-951-5526 or 800-732-8400
- Canada Customer Service: 800-387-7978
You can also visit the official Robertshaw website for additional resources and product information.
