Sounds like you are in Westchester County somewhere. That October ice storm was nasty last year.

I have a Cummins Onan RS 20,000 which I installed over four years ago. This is a propane powered
water cooled genset with a rated capacity of maybe 18 KW, 20 KW peak. I have two 200 AMP panels
in my house, and this allows one of them to be generator powered. Total all in cost back then
was about $US 20,000 with installation, genset, permits, propane tank, wiring, trenching.
It has about 60 hours on the clock now, so far no problems. I change the
oil and old filter each year myself.

Water cooled and lower RPM gensets are better in that the system is stressed less. However
the overall cost is about 2x an air cooled system. This is because air cooled are mostly
lawn mower engined based and are significantly lighter. This saves on installation because
you do not need heavy lift, nor a concrete pad. The downside is they run at 3,600 RPM and
are stressed to their limits. Over time I have seen the KW specified creep up in the marketing.
I think the marketing is correct in that the systems can reach the KW rating, however they
never say for how long. The other trick is to compare 1,800 to 3,600 noise wise. This is
easy, just stick you car in neutral, and run the engine at the two different speeds.
The water cooled genst I have is based on a Ranger Ford engine. I think the newer
RS 20000 versions from Cummins now use a Chevy based engine.

Note that your Honda EB6500 is one of the more quiet generators and a good one too.

The guy who installed my system is Tommy Keeler of Moonlight Electrical. He is in Putnam Valley.
He is good in that he has installed many gensets, and my one was his first water cooled one.
He did at that time have a small backhoe to use to dig the trenches for the gas line
and put in the genset. Try calling him 845 528 8467. I see he is still licenced in Putnam
county, so I guess he is still around. Tommy also pulled all the permits from the town
for me.

The actual genset I bought online from Costco. They are the cheapest place I know for the
quality gensets. You can also get help from the Costco which is in Portchester. Note
in general, Costco support for Cummins Onan is really bad. They have no clue.
But they do have a Cummins Onan contact number. That is what you really want.
I think the contact is Cummins out of Seattle somewhere for a Costco purchase.

My genset was delivered with a missing door hinge. Once through to Cummins Onan
their service was really top notch. A guy came out to see what was wrong. Then
came back the next day and put the missing part in for me. I was so impressed
that once the genset was all installed by Tommy, I paid a Cummins guy to come out
to check things over and "TURN ON" the genset. The Cummins division I used
was Cummins Metropower, and they are based in the Bronx, NYC. The guy
spent about 3 hours on site checking everything over and was very knowledgable.
He ran my genset, and asked me to load it up with air conditioners etc while
he tweeked the control parameters via a hookup to his PC diagnostics. Sort
of a custom tuning to my house requirments if you will.

Cummins Onan is also used in prisons and airports. I know this because on the
turn-on day the Cummins guy was late. He was fixing a genset at a prison, and
it too him a while to clear security to come to me!

Overall I think I may have over installed, however I never had any issues with it
and the service has always been very good. The company I work for also has
Cummins Onan gensets onsite, I think three of them.

Hope this is useful.

Best, Mike.