NATURAL GAS GENERATORS FOR HOME USE
The term "generator" in electric industry casually refers to a device containing a combination of an engine with an electric generator head assembled together as a single piece of equipment called genset. The gensets whose engine is fueled by NG typically cost about the same as propane-fueled devices and generally are cheaper than diesels. You can find them for sale at about $200-300 per kilowatt. Normally, permanently installed backup power systems are selected based on the type of the fuel you already use for the heating. Therefore a natural gas generator is an obvious choice of back up power device for the houses connected to an NG line. Besides private homes, NG gensets are utilized in commercial installations, although for such applications diesels are more common because of their higher reliability.
The main advantage of an NG-powered device is it's hooked up directly to the home's gas line, so you don't have to store any fuel. It can provide emergency power for as long as the fuel is available (except for some breaks for oil change and other required periodic service). The leading US manufacturers of residential NG gensets are Generac, Briggs & Stratton, Cummins Onan, and Kohler. Caterpillar makes primarily large industrial-grade devices. Coleman no longer makes gensets, and the assets of Coleman's Powermate were acquired by a company called PRAMAC. Generac-made models are also sold under brand names Guardian® and Carrier. GE is selling a line of automatic systems built and serviced by Briggs & Stratton. Generac Guardian
series has probably the broadest line of automatic systems with the power ranging from 8 to 20 kW for residential air cooled models and 25 to 60 kW for commercial water cooled. For the comparative ratings of top brands and selection recommendations see home generators review. Note that most manufacturers do not include a starting battery, which you have to
buy separately.NG gensets are available both online and from local dealers. You can often buy online for less, but you need to find a professional installer. If you prefer to work with a local dealer who may provide both installation and service, please complete a free quote request form.
Electrical connection to the house wiring system must be done via a transfer switch, which is usually included in the automatic systems.
Many residential NG models are actually bi-fuel: they can also run on propane after a simple DIY adjustment.
INSTALLATION BASICS
The manufacturing manuals normally contain a detailed installation requirements. However, it worth to know the basic details in advance to plan your layout. All generators must be operated outdoors only, but transfer switches are normally indoor rated. The installation and all the connections should be done by qualified professionals. Prior to the installation you should consult local fuel suppliers or the fire department to check the codes and regulations, and insist your installer follow them. Local codes may mandate a specific routing of gas line piping. Generally, the system should be located as close as possible to the fuel supply and to the main electrical service panel. The exhaust should be kept away from windows and doors. Install the generator on high ground where water levels will not rise and endanger it and allow sufficient room on all sides for servicing.
The genset must be mounted on a level surface. It is typically placed on pea gravel or crushed stone. Check local codes if a concrete base slab is required.
The pipe sizing, construction and layout must comply with NFPA 54. At least one manual shut-off valve must be installed in the gaseous fuel supply line. The fuel connection should be made by a licensed plumber. Make sure he uses AGA approved pipes and a proper pipe sealant or joint compound. Remember that natural gas is highly explosive. Even the slightest spark can ignite such fuels and cause an explosion. All installed gaseous fuel piping must be purged and leak tested prior to initial start-up in accordance with local codes, standards and regulations. When connecting the gas line to the generator use the flexible fuel line to ensure that vibration will not cause a leak at the connection points. Never bend the flexible fuel line (it must not be bent beyond 10 degrees). Note that natural gas, which is lighter than air, tends to collect in high areas if it leaks. Where the fuel line is to enter the generator, install a T-fitting to allow for the pressure monitoring. Once the system is installed, verify that the fuel pressure never drops below minimum, which is typically 5 inches WC or 0.18psi.
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