Tools / Generators
User Manual for Generac Guardian Series 17/20kW Residential Standby Generator
Quick guide for the Generac Guardian Series 17/20kW standby generator. Includes features, specifications, control panel operation, transfer switch options, and maintenance requirements.
Table of contents
Manual images
Click an image to enlargeQuick Guide from the Manual
The Generac Guardian Series 17/20kW standby generators are designed for residential emergency power. Key operational requirements include a 2-year/200-hour oil change interval and specific fuel pressure requirements (5-7 inches water column for Natural Gas, 10-12 inches for LP). The system is managed by the Nexus Controller, which handles automatic startup, voltage sensing, and weekly exercise cycles.
Product Overview
The Guardian Series features an air-cooled gas engine with an OHVI design for increased fuel efficiency and durability. The unit includes a weather-protective enclosure, an enclosed critical grade muffler, and a composite mounting pad. It is designed to operate on either Natural Gas or LP Gas.
Control Panel Operation
The Nexus Controller provides a simple user interface with a 2-line plain text LCD display. The mode switch allows for three settings:
- Auto: Automatic start on utility failure. Includes a 7-day exerciser.
- Off: Stops the unit. Power is removed, but control and charger remain active.
- Manual/Test: Starts the unit with starter control; the unit stays on. If utility fails, transfer to load occurs.
The controller monitors utility and generator voltage, manages engine warm-up (5 seconds) and cool-down (1 minute), and includes a smart battery charger that adjusts rates based on outdoor temperature.
Transfer Switch Options
Two transfer switch options are available depending on the model:
- EZ Switch (100 Amp): Available on 17kW models only. Features pre-wired conduits for easier installation and NEMA 1 indoor-rated enclosure.
- Nexus Smart Switch (200 Amp): Includes Digital Load Management (DLM) technology, allowing for the smart control of two air conditioners without additional hardware. It uses a NEMA 3R aluminum outdoor enclosure.
Maintenance
Routine maintenance is essential for system reliability. The unit features a full-pressure lubrication system with a 2-year/200-hour oil change interval. Scheduled maintenance kits are available (5664 for 17kW, 5665 for 20kW) to provide all necessary hardware for routine service.
Technical Specifications
Key specifications for the 17kW and 20kW models include:
- Rated Voltage: 240V
- Operating RPM: 3,600
- Oil Capacity: Approx. 1.9 Qts / 1.8L
- Sound Output: 66 dB(A) at 23 ft.
- Battery Requirement: Group 26R, 12 Volts, 525 Cold-cranking Amperes minimum.
Accessories
Various accessories are available to enhance the system, including a Cold Weather Kit (6212) for temperatures below 32°F, Auxiliary Transfer Switch Contact Kit, Fascia Base Wrap Kit, and wireless remote monitors (Nexus Wireless Remote 5928 or Advanced Nexus Wireless Remote 5951).
Manufacturer information
Generac Power Systems, Inc.
Practical help
Common problems
Engine fails to start
Check battery charge (Group 26R, 12V, 525 CCA min) and ensure fuel supply is connected and pressure is correct.
Unit not transferring power
Verify transfer switch settings and ensure utility voltage sensing is functioning. Check for any active fault codes on the Nexus controller.
Overheating
Ensure the enclosure is clear of debris and that there is adequate ventilation around the unit.
Before use
- Verify fuel pressure: 5-7 inches water column for Natural Gas, 10-12 inches for LP.
- Install a Group 26R, 12V, 525 CCA battery.
- Check engine oil level.
- Confirm transfer switch is properly wired to the distribution panel.
- Ensure the unit is installed on a level surface using the composite mounting pad.
Specs in practice
- Rated Voltage
- 240V output for residential power.
- Operating RPM
- 3,600 RPM for constant 60Hz frequency.
- Oil Capacity
- Approximately 1.9 Quarts (1.8 Liters) including filter.
- Sound Output
- 66 dB(A) at 23 feet under normal load.
Images and diagrams
- Front and left side views provide dimensions for installation planning and clearance.
- Switch options diagrams detail the physical dimensions and terminal wire ranges for the EZ Switch and Nexus Smart Switch.
Model compatibility
- EZ Switch is available on 17kW models only.
- Nexus Smart Switch includes DLM technology for managing air conditioner loads.
- Wireless remotes are not compatible with CorePower or EcoGen systems.
Manual page author
Emily Carter
User documentation editor
Prepares concise manual descriptions and highlights the most useful setup, operation, and maintenance information for readers.