On Tue, 20 Dec 2011 08:05:14 -0800 (PST), "
wrote:

On Dec 20, 10:16*am, "Pete C." wrote:
Existential Angst wrote:

.
I thought natural gas-powered standby generators would purr.... * apparently
not.

They are as loud as any typical small air cooled engine. If you want
quiet you have to move up to a commercial grade liquid cooled model.

I wouldn't expect the same engine to have any significant
difference in noise based on what fuel you put in it. You
do get about 20% less power out of the same engine if
it runs on nat gas versus gasoline. That should equate to
some difference in noise, but doubt it's significant.

The fuel isn't going to matter a lot - it's still getting compressed
and ignited, and while Propane and NG have a slower and more stable
flame front it's still combustion.

I'm wondering how much of the noise is exhaust noise, how much is just "unit
noise" -- engine clanking, fans, etc.

Most noise from a small air cooled engine is from other than the
exhaust, thus a good muffler does little to quiet them.

Not sure how much of the noise comes from where.
I've have seen some Honda portable generators though
that were very quiet compared to low end Chinese ones.

There is always some noise from the cylinder walls and other
mechanical items on the generator - the exhaust only drowns them out
because they don't spend much on the mufflers. Why bother, when they
are selling to a price point and not a noise level point.

I'm thinking of keeping mine inside (theft, consideration of neighbors) --

Inside is a bad idea unless you build it into a sealed externally vented
space with CO detectors adjacent.

This was discussed here a couple months ago. Someone
posted the requirements for indoor generators for their
location, ie fireproofing, venting, detection, etc and it was so
tough that for all practical purposes
you could forget about it for a typical residential application.
Don't know what other locations codes are, but I'd
suspect it isn't going to be easy. But before going down
the in-house road, I would check the local codes.

If you want to see for yourself, call your local Phone Company and
go get a tour of their generator room, that one has to meet the local
building codes. It's complicated, but not beyond a resourceful RCM'er
to set up.

It's in a fireproof room (5/8" 2-hour Drywall) with 2-Hour rated doors
and automatic closers, etc - Just like your garage at home.

They have large vent grilles on the exterior wall, low and high, for
cross ventilation. Just like your garage at home, but bigger and
there are exhaust fans to make sure.

There is usually an exterior door so the Firemen have a way in without
letting the fire into the building, Just like...

There is an exhaust pipe leading outside to get rid of it up high - on
the wall or roof, away from other air intakes. Just like... if you
installed an exhaust hose system to work on your cars inside in the
winter.

There are fire sprinklers, just like you can install in a house if you
choose to - and they're starting to require them in new homes.

And several fire extinguishers rated for the use and sized for the
fuel load, and all the people working there get periodic live-fire
training to use them effectively. You can get your local Fire Station
to teach your family and friends the basics, then they hand you a
charged extinguisher, light off a quart of gasoline in a steel pan,
and say "Here, your turn!" and you find out how to do it for real.

The fuel source is piped in remotely to a 5 or 10 Gallon Day Tank next
to the generator, and a bare minimum of other flammables are stored in
that room, so a fire in the generator goes "Pfft!" and out - it
doesn't have a lot of fuel to take out the whole house. You do the
same thing, the Gasoline cans are in a separate "Flammables" locker
either outside (I have a steel shed) or clear on the other end of the
garage.

They have a way to route cooling air straight into the radiator and/or
a way to route hot cooling air out. Or they have the radiator remote
mounted on the roof.

is it generally straightforward to hose-clamp a metal flex hose to a
tailpipe? *IS there a tailpipe on the small units to clamp to?

Go look at the display unit in any 'Depot or Lowe's. I believe there is
a stub of tailpipe sticking out of the housing.

The ones I've looked at have an oval flange with two screws holding
the USFS Approved Spark Screen over the exhaust outlet - making a
flange that fits or getting a spare from the maker, then adapting it
to connect flexible metal exhaust hose to a rigid exhaust pipe headed
(up or out) is your RCM Skills Test.

Any experience with these types of units, brands? *Recommendations?

The home standby units are intended for just that, home standby. They
are not remotely close in construction to the commercial grade units
even in the sizes where the residential and commercial models overlap in
rated capacity. They will do the job, but will not last through very
many long outages, especially if loaded near capacity. If they are sized
to run perhaps half load, are well maintained and typical outages are
only a few hours duration they are fine. If you are in a rural area and
days long outages are common invest in a commercial grade unit.

A neighbor here had a $7K Generac that was about 5 years old. It ran
for 4 hours during the hurricane in August, then quit. Company that
installed it told him it was shot and not worth fixing.

Company that installed it should have their butts sued off for
forgetting to put in the motor oil...

Even the cheapest should be good for 1,000 to 2,500 hours if treated
halfway decent.

If I were looking for emergency power, I'd go with one of the
portable units. There are some that are available that run on
nat gas. Or there are kits available to make most of them into
either permanent nat gas or even tri-fuel units that can use
gasoline, nat gas, or propane. One of those together with
an inlet and lockout breaker arrangement from Interlockit
is what I would use. You can have the inlet installed outside,
nat gas line available and just move the generator there
when needed. And if that generator fails, you can buy a
whole new one for a fraction of the price of the standby
units. The generator is also available for other use if
needed. I could put the above together for $1000

You do get what you pay for. If I was going through that much trouble
to install it in a house, I'd be looking for a fairly recent
Commercial model permanent mount diesel plant.

The Contractor model portables are built down to a price, not up to a
service specification they have to meet or exceed. Sometimes you can
get a good deal on a refurbished Commercial unit for a song.

-- Bruce --