Depending on their engine, stationary emergency gensets can run on natural gas (NG), liquefied propane gas (LPG) or diesel. We also included in this review one Generac's gasoline-fueled portable model because it can be used as a whole house generator due to its high power. Many residential fixed models are bi-fuel and can run on both gas and propane, although they are shipped configured for a particular fuel, usually propane. You will need to do a simple adjustment to convert from one type to the other. Note that the rated wattage varies slightly with the fuel: the chart above give both NG and LPG watts. Diesels are more reliable, but they are the most expensive. Because of their higher cost, they are more suitable for industrial applications. Standby devices under 20kW are normally air cooled. Gensets about 20kW are usually liquid cooled. For additional information and lesser known details also see our guide
to standby home generators. One of the most important things to determine when choosing your backup system is how much electrical power your home will need in emergency. Check out our sizing guide
for the recommendations.
So, what brand to choose? The main U.S. manufacturers of gensets for homes are Generac, Briggs & Stratton, Kohler, and Cummins Onan. Most of other brands are just private labels. Generac
accounts for 65-70% of all North America gensets sales. Its latest home generator systems up to 30 kW are CARB-compliant, which is required for California. The new EPA requirements are harmonized with CARB, so for newly designed or imported models similar emission limits supposedly will be required nationwide. Generally, as far as I can see, Generac's Guardian® series is sold at one of the lowest costs per kilowatt among top brands in 10-20 kW range. Any model from this product line can be a cost-effective solution for a typical private house or a small business. Guardian® packages comes in two basic types: models at 17kW and higher can be bought with an optional "smart" load management. It can temporarily shed non-essential circuits when the genset approaches its maximum capacity. This allows you to handle several a/c with a smaller system. Many people buy General Electric
generators because of their brand name. In reality, their systems are built by Briggs & Stratton, although it's possible they have to meet special GE requirements. GE does provide longer warranty, which may or may not be worth the extra price. B&S also powers Milbank. If you can't find enough users feedback on GE and Milbank, you might just read customer input about Briggs & Stratton- since they are built by the same company they may have similar performances.
Generac 6237 received 2013 "Best Buy" rating from Consumer Reports magazine. In my view, their choice is strange because at 7,000W this part is good only for essentials. Of course, if you don't need to feed a central a/c or other large appliances, you may consider this model. Otherwise, an average home with up to 4-ton central air conditioner typically needs at least a 12 kW device. For 5-ton a/c you likely need even larger system, such as GUARDIAN® 17/16kW model 05873 (see our review
). To select a system for such applications, see our guide to starting a/c and motors
). Popular Kohler's 14RESAL was also recommended by CR magazine. Kohler says its units restore power in as little as 10 seconds. This brand has one of the best warranty in the industry and is a good choice too, although it seems to be somewhat more expensive.
Of course, besides the purchase price, there are costs associated with the installation. Particularly, you need to check if your gas or propane service is sufficient to provide the required amount of the fuel. Our chart shows cubic feet per hour (CFH)
for both NG and LPG. By the way, B&S used to make a dual fuel 7 kW #40248, which offered flexible connection options. It included a propane quick connect kit that gets you up and running immediately from two BBQ tanks as if it was a portable genset. You could later on connect it to natural gas line when you choose to. Unfortunately, this part is now discontinued.
Note that the manufacturers usually state rated power for 60 o
F (15.5 o
C) ambient at sea level. You need to derate available watts typically 3.5% for each 1000 ft (305 m) above sea level and 1.5% for each 10 o
F (12.5 o
C) rise in ambient temperature above 60 o
F. So, a 15 kW device would provide only about 14.1 kW at 100 o
WHERE TO BUY
. If you want to buy online at a discount, in my view, Amazon's Home Improvement
department is a good place to start your search. It has a wide selection of Generac GUARDIAN®, Briggs & Stratton and other top ranking brands. Amazon usually offers free shipping on the gensets they carry. If you prefer to buy from a local dealer or an installer who might be able to handle delivery, installation, and even financing, please complete our free quote request
form. As far as I know, regardless on where you bought a system, you can normally order the installation from their local dealer, or hire your own contractor.
All listed devices provide split single-phase 120/240VAC 60 Hz output.
Prices in the chart do not include taxes, shipping and installation (although some online retailers offer free shipping).
The devices compared here represent only a small sample of all available models and brands. For other models as well as official specifications, datasheets and warranty info visit the websites of the respective generator manufacturers.
The part numbers in our chart are arranged in no particular order. The data and features (including ability to run a specific size of central air conditioner) are based on the published specifications of the respective manufacturers or retailers.
No attempt was made to verify products compliance to their specs.
While all attempts are made to provide accurate, current, and reliable data, all info here is provided As Is- we assume no responsibility for any errors. Product reviews are provided for information purposes and reflects only the opinion of the author. The sole responsibility when selecting a product rests with you- see important Disclaimer linked at the bottom of this page.