As stated, the Magnum AGS will work with the Onan QuietDiesel 8000 generator. That's what I have. I'm quite happy with it, although I have had flaky operation on two occasions: in both cases it was loose wires to the AGS module, so it is a good idea to inspect them periodically (annually?) and make sure they are tight.
There are two versions to the Magnun AGS: a stand-alone version and one that works with the Magnum inverter/charger and remote control. If you already have that inverter/charger and remote, then it's a no-brainer: go with the networked Magnum AGS and you will be able to run it from your inverter control panel.
For installation of the Magnum, you will need to run power, ground, four generator control lines to the AGS (Start, stop, common, and status.) Those last four lines may need to come from the generator, or could be available closer if you have a manual start/stop switch and status light inside. In addition, if it is the networked model, you will need to plug a phone style cable between the AGS and inverter/charger.
There are DIP switches inside the AGS module that need to be set according to the generator type. If you turn all of them off, it will be compatible with your Onan QuietDiesel. To start the generator, it will simulate holding the stop button for 10 seconds to prime the fuel pump, wait four seconds, then hold the start button for 20 seconds to give it time to preheat and start. To stop the generator it will simulate holding the stop button for 10 seconds. Using this sequence, I'm not aware of any times where the AGS module was not able to properly control my generator.
The Onan AGS may be more expensive, but the installation should be easier: there is a box that mounts by the generator, and then the control panel is wireless so you don't have to run extra wires to it.
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