Kirk,
I got a 10kw propane genset with an auto-transfer switch - dirt cheap from a remote cable tv site. They ARE out there, used, but VERY well maintained, and CHEAP - in the 10-30KW range. Mine dates back to the late '70s, with a great Wisconsin Robin Engine. Everyone has been upgrading their systems, they ARE out there. Still good, 12v Gell cell batteries can be had for free. Just ask around.
These things were sold as package units, with the transfer switch included in the mount, so they're very simple to hook up. Talk to your local cable TV tech., telephone tech, cellular tech and see if they got one they're getting ready to move out - be sure to tell them WHY you want one - you got a good reason, they might help you out.
We have SEVERAL Generacs and Onan gensets, as a small part of my job, I have to make sure they run.
Do not buy a Generac, ever! In fact, I wouldn't ever buy a diesel unless I lived in Flordia. Without a tank heater (engine block) diesel's don't like to start in cold weather. How much does it cost to run a 1500 watt tank heater? $$ OUCH! If you live up north, and your power goes off in the winter, it'll be too late to plug in the tank heater. We keep our heaters on, 24/365 - those diesel engines are 180 degrees and we
still have problems starting them. Oh, yea, they start for all the PM tests just fine, but let an ice storm roll through, and if it's a Generac, it's "iffy". The engines are not made by Generac, but by every Tom, Dick and Harry, some domestic, some foreign - I can't read the script on half of the smaller ones, maybe it's chinese?
One thing about water cooled generators, they might be quieter than air cooled, but "wet stacking" is a huge problem if they don't run long enough. Diesel gensets need to run till their HOT, the oil needs to get hot - or moisture is gonna take it's toll on your unit. Without stabilizers, gas goes bad, reformulated gas absorbs moisture, etc., diesel gells in cold weather, not so with Propane. Components on diesels are expensive to replace!
My old propane generator starts and runs like a champ, warm weather or cold, rain, ice or snow - and I don't have diesel or gas smell around the house to contend with. It's hooked right into our 500 gallon propane tanks regulator (at the house), like the furnace - simple, neat and easy to deal with. It ran it off a 5/8" garden hose during last hurricane, sitting on the basement stoop (49hrs). Now I got the automatic transfer switch installed, with all the circuits I want to maintain "normal living" during an extended outage. This includes the well pump, electric water heater, 90% of the lights & outlets, freezer, fridge, ceiling fans, furnace, etc. I left the electric stove and AC off the system.
If you've already got a gas generator and want to convert to propane or multi-fuels, check out this web site for conversion kits.
http://www.propane-generators.com/
So far, we've suffered a power outage each month. From a minute or two, to 49 hours. I'm glad my family will not be out there trucking diesel or gasoline when things get really nasty.... Unfortunately, I'm one of those guys that gets called out because of it.
If I had to buy a NEW residential size, I'd be looking for a HONDA 10-12kw electric start and convert to propane. Derate 10% for propane. Forget the multi-fuels if it's a residental unit, set in place, never to move again. My neighbors and I started with those 5KW gasoline extended run $500 units... I'm making mufflers for them to quiet them down so we can sleep... They're fine for temporary portable power out in the field, but I wouldn't trust one to keep my Dialysis machine running.
Whatever you do, OVER SIZE! When the smaller units start loading up, the frequency/voltage drops and all kinds of terrible things happen to devices with electric motors (well pumps, furnace blowers / pumps, fridges, freezers, washers / dryers). We lost a bunch of compact flourscent lights and a nice stereo due to an intermittent miss on our other unit... some stuff is pretty sensitive.
That's my 2cents worth.