What Grant said. Also, don't oversize because that significantly increases fuel burn at idle. In other words, don't size the system to run the whole house normally. Standby units are almost always in standby, which IMO rules out diesel or gasoline for fuel. If propane, you'll need a big tank because (1) you'll burn a lot and (2) small tanks may not maintain pressure at high flow rates. Standby units are not maintenance free; you'll need to change oil and filters and check/service the battery at least annually; gasoline and diesel units requite more MX. Generac and rebranded Generac (Centurian and Guardian) and a few others come with an auto transfer switch (big $$ as a stand-alone purchase) which is a major plus for those packages. Remember that the unit needs to be weather-proof as it will be outdoors all the time and must be located at least 3 ft away from the house, more if there are windows nearby. Give thought to which loads will be on the generator and how they'll be connected. For a big generator, it may be easier to add a subpanel for those loads and run the subpanel off the transfer switch; this has the added benefit of allowing you to add/change some loads in case you forget something important.
At my last house (in FL), my neighbor (who owned electrician business) had a huge water-cooled 40KW natural gas unit. And he let us hook up after hurricanes (usually 2-4 days) while power was off. This happened a lot in those days. We learned that a little power went a long way: just 1-2 lamps, the refrigerator, computer, TV, and a couple fans made a huge difference. In fact pulling power through over 200ft of 12 ga extension cords, we found we couldn't run the computer and refrigerator at the same time but that small amount of power was still wonderful. Scott -----Original Message----- From: mercedes-boun...@okiebenz.com [mailto:mercedes-boun...@okiebenz.com] On Behalf Of G Mann Sent: Tuesday, August 30, 2011 12:02 AM To: Mercedes Discussion List Subject: Re: [MBZ] OT - Natural Gas generators Some items to consider in generator selection for use in a real disaster. 1. If it's an earthquake disaster, Gas lines will be broken, or as a precaution all main supply valves will be shut off until safety can be ensured via inspection for the whole area. During that time, your NG generator will be without fuel, you will be without electricity. 2. If it's a hurricane, with damage on even small scale, homes will be blown away ripping out the gas line connection which will once again require shutting down the main supply to the gas grid system for the entire area. Result, you are out of gas and electricity with no fuel source for the "backup generator" 3. Nuke attack.... Let's don't go there. However, presuming you survive, will the gas mains? Size selection is a matter of calculation of electrical load for "necessary" function. Easy enough to do with a bit of thought and work. Fuel choice: Gasoline doesn't store well, goes stale with time, and presents a real fire hazard for storage. Diesel has fewer flash fire issues, lasts much longer with simple biocide treatment to keep alge growth in control. It is hydroscopic so should be sealed against water intrusion. Cost: Gas generators large enough to run a house systems can be in the "less than a 1000 bucks range. Diesel gensets cost more [$1500 to $10K about]. lasts longer in useful hour life span, aren't available in smaller sizes [3500 Watt is about the low end size]. Propane fueled generators use more fuel than either gas or diesel simply because propane [or natural gas] has less BTU per comparable volume of fuel. Propane stores pretty well, as in independent source from the vulnerable NG grid , as a third option. However, you may have local permit issues with a large propane tank in your yard. My personal experience: I live on a remote 36,000 acre ranch [that's 35 sq. miles] in western Arizona. The nearest power pole is 42 miles away, so for me, "normal" is your "emergency". I have all the electrical items [likely] that you have and the order of electrical generation works for me like this. 1. Solar system , 4.5 KW system.. Primary. normal house things, computer, lights, refrig. 2. Diesel Generator, 7.5 KW system... Secondary.... 120/240, 3 phase available 3. Diesel Generator. 3.5 KW system... Secondary backup. 120/240... 4. Gas Generator, 3.5 KW system.... Reserve secondary backup, mobile rig 120/240 with welders on trailer, also wired to run well pumps. 5. Gas Generator, 1.2 KW system.... House system backup reserve, [dedicated to refrig/deep freeze and lights. [phased usage required since it's to small to handle start loads on all the items at one time. 6. Numerous 12 volt solar panels dedicated to small battery banks to run things like the electric entry gate, security cameras, electrified fences, communication relays, etc. As you may guess, I'm a great fan of not depending on public services [since there are none where I am].... respectfully suggest that in a real emergency you quickly find yourself in the same situation. Grant... On Mon, Aug 29, 2011 at 8:07 PM, OK Don <okd...@gmail.com> wrote: > Thanks for putting the "generator hat" on! > I ran a crude spreadsheet calculation against the propane generators on > Amazon, and found this one - almost too good to be true -- > > http://www.amazon.com/Sportsman-GEN7000LP-7000-Watt-Portable-Generator/dp/B0 04BKI0ZM/ref=sr_1_1?ie=UTF8&qid=1314673188&sr=8-1 > > It produces 8.86 watts/$, vs. a Generac 7kW at 3.89 watts/$. > > On Mon, Aug 29, 2011 at 7:52 PM, LWB250 <lwb...@yahoo.com> wrote: > > > <Generator hat on> > > > > The whole thing when it comes to stationary standby generators is > > determining what your critical loads are. Until you do that, you're just > > flailing around. > > > > Make a list of "must have" loads and write down their wattages. > > > > The worst case ones will be small, fractional horsepower motors, like > sump > > pumps and furnace blowers. Single phase motors are horribly inefficient > > when it comes to starting current, so you've got to have enough reserve > to > > handle their inrush current. > > > > From there look at things like fridge, freezer, basic lighting, garage > door > > opener, etc. > > > > Generac and other manufacturers have some good sizing programs on the Web > > that allow you to do the calculations. Just keep in mind that these are > > general values and not 100% accurate. It's a guide to give you an idea > of > > what you need capacity-wise. > > > > Once you know what you need kW-wise you can start looking. > > > > Stationary sets run off propane vapor or natural gas. Be careful when > > shopping, as propane has a much higher BTU content than natural gas, so > > machines are often rated on propane with deration percentages if it's on > > natural gas. Usually you'll see a 10%-15% deration on natural gas. > > > > Install often equals the cost of the unit, so be prepared. If you can do > > any of it yourself this is the place where you can save some serious > bucks. > > You will need a licensed electrician to do your transfer switch, unless > > you're doing downstream of your main breaker. This is typical, as a > branch > > circuit will be run to a transfer switch that feeds a small distribution > > panel where your critical loads have been broken out from the main panel. > > > > While it's more expensive, it's foolish (in my opinion) to go with a > > stationary generator and not have an automatic transfer switch (ATS). > Think > > about if you are away, and the power goes out. If it's an extended > outage, > > you risk food loss, possible damage to your home depending on the climate > > and season, etc. Sure, it's a peace of mind thing, but the additional > cost > > is minimal in the grand scheme of things. > > > > Generac has really dialed in the consumer home standby market, and done a > > good job with it. You'll find their products marketed at all the big box > > home improvement stores under the "Guardian" brand, among others. They > have > > done a very good job of balancing the price point vs. quality and > longevity. > > You can go more expensive, such as a Kohler, but even though I have some > > bias as a former employee of both, the Kohler is a premium product that > > effectively does the exact same thing the Generac does. > > > > Maintenance is the key to longevity on these, just as it is on your MB, > and > > it doesn't take any special tools or knowledge. Change oil and filters > > annually and keep it clean and you're pretty much done with it. > > > > If anyone has specific questions they are welcome to send me a PM. > > > > Dan > > > > </Generator hat off> > > > > > > > > > > > > -- > OK Don > 2001 ML320 > 1992 300D 2.5T > 1990 300D 2.5T > 1997 Plymouth Grand Voyager > _______________________________________ > http://www.okiebenz.com > For new and used parts go to www.okiebenz.com > To search list archives http://www.okiebenz.com/archive/ > > To Unsubscribe or change delivery options go to: > http://mail.okiebenz.com/mailman/listinfo/mercedes_okiebenz.com > _______________________________________ http://www.okiebenz.com For new and used parts go to www.okiebenz.com To search list archives http://www.okiebenz.com/archive/ To Unsubscribe or change delivery options go to: http://mail.okiebenz.com/mailman/listinfo/mercedes_okiebenz.com _______________________________________ http://www.okiebenz.com For new and used parts go to www.okiebenz.com To search list archives http://www.okiebenz.com/archive/ To Unsubscribe or change delivery options go to: http://mail.okiebenz.com/mailman/listinfo/mercedes_okiebenz.com