I don't like the smaller Generac units for a number of reasons.
First, the quality of the "pre-packaged" ATS switchgear doesn't exactly inspire condfidence, and doesn't allow for much flexibility, like excercise times, automatic excercise with transfer, and so forth. (If you're not excercising with transfer, you're wasting your time.) I would much rather have a genset with a two-wire start that can be used with a more "substantial" ATS of my choice. Plus switched neutrals if required by local code are almost impossible with lower end Generac's.
Second, up until recently, you needed very high (11-14" WC) natural gas pressure to run these units, though now they can run on (5-7" WC). Onan is much more flexible, usually allowing 7" to 15" WC, though many can run with less without any problem.
And finally, I've found these units can be very finicky to get going, and there's often insufficient space to make connections. I don't like the idea of attaching a NEMA 3R box outside of these things simply to reduce the conductor size so the genset can accept them. Annoying. And it seems too many of these units come DOA, and need parts replacement. Never seen and Onan or Kohler come DOA.
Now when you get into the bigger Generac's, like 100KW and up... those can be pretty impressive, both with the genset and ATS switchgear. Those tubrocharged CAT engines are a sight to behold. I really don't like the consumer grade stuff.
I personally like Onan - have one myself - but I am very impressed with the new Briggs & Stratton units and their load management controls. B&S will soon be shipping their new EM20 genset, a 20KW air cooled unit with 28KW surge capacity that can manage TWO 5-ton central A/C units with the Empower controller. And I guess I like B&S because I could work on those motors as a kid, and they're pretty darn reliable. But of course, the motor is only half the equation in a genset.
Joe
