Thesandman
I'm looking into installing a generator and would like the most reliable air cooled model with an aluminum enclosure as we live a quarter mile from the ocean in Massachusetts. I was originally looking at the Guardian 9kw model, but a local dealer recommended I upgrade to 2 cylinder as the single cylinder can have a hard time starting at below freezing temps (dealers words, not mine). In addition, I noticed that Generac's current promotion of a free extended 10 year warranty excludes the single cylinder model which makes me question its reliability if Generac is seemingly less willing to extend the warranty. Has difficult starting in cold weather and lower reliability for the 9kw been others experience?

The next option would be the 11 kw model, but I'm willing to go to the 16kw with the G-force 1000 engine if it will give us a more reliable generator. I tried reading up on the g-force 400 vs 500 vs 1000 engines, but could only find vague descriptions on Generac's website with no indication if one engine line is better built than the other.
Quote
78buckshot
We sell and service far more of the 992c.c. and 999c.c. units than the smaller ones and have fewer problems with the big twins. For the cost of an install I would not consider a 7kw - 11kw unit.
Quote
nrp3
I have high hopes for the 9 kw being a good product. I only have one out there and so far so good. That being said, in the past, the smaller the unit, seems the more problems had. I sell Kohler and Briggs too. This seems to apply to them as well. Without seeing what you need for backup, bigger is better generally and this isn't a sales tactic either. Who installs as well as maintains it, can be as, or maybe more important.
Quote
cookelec
I have to agree with 78buckshot. We repair a lot of 992/999 engines, but there are more of them installed in this area than the smaller ones. I would stay away from the one lung engines and the 540 engine seems to always wind up leaking oil at some time through the front seal. I don't know why but they do. Considering the money you are about to spend, I would not use anything less than 16KW, but a 22KW with a whole house transfer switch gives you all you can achieve in an air cooled installation. But no matter which way you decide remember, the equipment is only as good as the install and future service performed.
Quote
BrianMartin
If I ever get a phone call in the winter from a customer telling me the generator didn't start, It's almost always the 7 or 8KW single cylinder in over crank... I wouldn't buy the 9kw unless the budget made it the only option available. The 11Kw's are pretty solid, as mentioned some do leak oil (not in large quantities mind you), but there is more space inside the enclosure to work on them... The 999cc 16KW and up seem to be the most trouble free for me, and it's what I would spend my money on. That being said, the 11 KW is noticeably quieter.. And they all have the aluminum enclosure.. The 22Kw however comes standard with the skirt that covers the mounting holes at the bottom of the unit..
Quote
Thesandman
Thanks so much for the great feedback! I will plan for the 16kw model
Quote
Skip Douglas SkipD
Thesandman;n58896 wrote:
Thanks so much for the great feedback! I will plan for the 16kw model
Are you planning to use the generator as part of a "whole house" system that would power everything in the house during a utiility power failure or do you plan to have the generator back up only certain circuits in the home? The reason I ask is because there is a requirement in the National Electrical Code that a generator be sized to be able to power the entire load that is automatically switched to it. There are specific rules in the code defining how this load value is calculated. With automatic load switching, it gets a lot more complicated than simply guessing at the size generator to purchase.

Skip Douglas
Quote
Thesandman
My goal is to power only the essentials, such as refrigerators, furnace blower motor, and the intermittently the microwave oven.  Given my low expected power demand, would going with a 16kw gain enough of a real world benefit to make up for the extra cost and fuel use (though fortunately I'm on natural gas)?    
Quote
Thesandman
Thesandman wrote:
My goal is to power only the essentials, such as refrigerators, furnace blower motor, and the intermittently the microwave oven.  Given my low expected power demand, would going with a 16kw gain enough of a real world reliability benefit to make up for the extra cost and fuel use (though fortunately I'm on natural gas)?    
Quote
patmurphey
cookelec wrote:
...I would stay away from... ...the 540 engine seems to always wind up leaking oil at some time through the front seal. ...


It was reported on some 10kw Nexus 10kw 540 engines (not mine). Do you know for a fact that it has continued to the present day on the Evolution 11kws?
Quote
DanS26
It has been my experience and many of the reported oil leakage problems of the 540 engine that the major cause was a breather gasket assembly that loosened or was improperly torqued at the factory.  That problem was easily fixed with longer bolts and some Loctite.
Quote
cookelec
I had 2 11 kw gens this summer that were still under warranty (Evolution) that had considerable oil leaks. I thought the problem was the breather but it turned out to be the front seal on both. I still replaced the breather while I was in there. They are not leaking now.
Quote
Thesandman
Thanks for all the comments. 

Given my needs, I'm likely going with the 11kw model and deal with the oil leak if it arises as it does not seem to be catastrophic (it's a little surprising that generac has not resolved this issue).  Hopefully another 10yr warranty promotion will come up over the next year, at which point I'll pull the trigger
Quote