HOME GENERATORS BASICS
STANDBY WHOLE HOUSE AND PORTABLE GENERATORS- REVIEW, COMPARISON, and SELECTION GUIDE
A fuel-powered device that can supply electricity to your house during power outages is casually referred to as home generator. During an emergency, it allows you to continue using essential appliances and lights. Since such a device includes an engine and an alternator mounted together, a technical term for it is engine-generator set or genset.
HOW TO CHOOSE A GENERATOR. First, let's quickly go over the different types that are out there. Home generators can be stationary (standby) or portable.
REVIEWS and RATINGS OF RESIDENTIAL STANDBY MODELS
They run on a variety of fuels, such as gasoline, diesel, natural gas (NG), and liquefied petroleum gas (LPG). Each type has its pros and cons. Portable gas models are relatively cheap. For example, you can buy a 4000W set for about $300. See also our pics of discount generators. However, such devices have short run time: you would need to refill their tank several times a day if you run them continuously at rated load. In addition to this, they are not suitable as a long-term power backup since the pumps may not work during a wide spread blackout. In Florida most gas stations already run dry a few days before hurricane Irma arrival. For a long term emergency consider standby sets. They can provide continuous power for the home because they are hooked up to an external fuel source, such as NG line. Some portable devices can also be fueled from an external source and can therefore provide extended run time too. The main differences between them and stationary models are in their connection and activation. A portable device has to be rolled out from the storage, filled with fuel or hooked up to a fuel line, manually started, and connected to your loads. A fixed standby generator by contrast is already connected to both the house wiring and the fuel source. Therefore it can start immediately either by a push of a button or automatically. Automatic systems have an auto transfer switch. It can sense a power outage, isolate your electrical wiring or designated emergency circuits from the grid, and start the genset. When grid voltage is restored, such a system will connect you back to the utility lines and will turn itself off. You don't even have to be at Home to activate it. Note that the typical transfer time of an automatic system is 10-30 seconds. Therefore, if you run important computer applications, you may still need a UPS. It can prevent data loss during the transfer time. Note that even though permanently installed natural gas powered gensets can provide practically unlimited run time, you still need to periodically shut them down to change the motor oil. With some engines you will need to do it as often as every 50-100 hours of operation.
This is another reason why a UPS will be useful.
In addition to the convenience of an auto starting option and practically infinite run time, permanently connected standby systems offer power levels higher than portables. Their rating ranges anywhere from 5 kilowatt up into hundreds of kW. Such systems do increase the value of the house. All this makes them the best whole house generators for power outages, especially for the long-lasting ones. Of course, they are more expensive and require professional installation, which are their main disadvantages. If you want something that can be used right away, obviously, a portable device is your only choice.
So, what to look for when you are choosing a generator for the home? My advice is: aside from wattage and cost, the main things to consider are the duration of time you may need emergency power, fuel availability, and convenience of use.
SELECTING THE FUEL. If you go for a stationary type, your choice of fuel is determined by the source you already use for the home's heating or by the fuels available in your area. Note that most residential generators are bi-fuel and can run on both natural gas and LPG (casually called propane). You will normally need a simple field adjustment to convert from one type to the other. If like most homes your house is already supplied with gas, or if LPG is readily available in your area, a bi-fuel NG/propane genset is your logical choice. See our detailed standby genset review for ratings and characteristics of various systems. Among major brands, the Generac's Guardian® and Briggs & Stratton IntelliGen models probably have the lowest cost per kW. In my view, given their 5-year warranty they are the best buys. You just need to pick the right size. CR magazine pick in 2013 was 7-kW model 6237. They now have a newer model 6519. However, this size may not be sufficient if you have a central air conditioner. As a rule of thumb, an average house with up to 5-ton central air conditioner typically needs a system rated 15-17kW or greater.
Here are some lesser known details you need to know when you are selecting a natural gas generator for your home. A typical gas meter is rated to 250 CFH. This may not be enough if you are adding a large genset. An engine will not provide full power if it is not supplied with the fuel amount specified by its manufacturer. In this case you will need to ask your utility company to upgrade your existing meter to a higher-volume one. Also, some older models may require the gas pressure to be greater than the standard delivery pressure available to your house. Be sure to check the model's requirements. The typical pressure in residential installations is 0.2-0.25 psi (5-7 inch water column). If you choose a device that requires greater psi, your meter will have to be changed to a higher pressure one. You will also need to install an additional regulator to drop the pressure to the normal level for the rest of your appliances. The above upgrades may cost anywhere from zero to $5,000.
A stationary NG system seems to be an ideal power backup for the whole house. Nevertheless, in an unlikely case of a major natural or other disaster the gas supply may be interrupted as well. In this case, you may switch to propane tank if you have a bi-fuel system. If NG service does not exist in your neighborhood, you probably have a large propane tank that is periodically refilled by a local distributor. Propane has practically unlimited shelf life and it is normally obtainable during power outages. In can be used in both fixed and portable devices. In my view it is the best choice for portables. You may also consider a diesel system. Diesel engines are the most efficient and maintenance-free of all types. However, they are also the most expensive. This makes them more appropriate for industrial applications. In addition to this, diesel, like gasoline, may not be available during a major blackout. For the current deals on some of the top rated residential models see our discount generators picks and review.
GENERATOR INSTALLATION TIPS. Normally, a stationary genset is mounted outdoors on a cement pad. Preferably it is placed near the fuel source. Many models already come with a mounting pad. In any case, you still need to prepare a location that is flat and has provisions for water drainage. To prevent exhaust gases from entering the house, locate the unit in a well-ventilated area away from doors or windows (2015 Edition of NFPA 37 requires at least 5 feet separation). Due to the heavy weight, you may want to request lift gate service when the freight company calls you to schedule the delivery. Otherwise, have at least four strong persons present to unload the device.
FOR SELECTION, SIZING AND CONNECTING HOME GENERATORS GET OUR COMPLETE GUIDE.
HOW TO WIRE YOUR SYSTEM. A standby power backup device connects to the house wiring via a transfer switch, which is usually installed indoors. Its prevents "backfeeding" into utility lines (which is dangerous and illegal). It also protects your device from damage by preventing utility from applying voltage to your house wiring while it is running. In any case, without a transfer switch your genset will likely be overloaded or damaged by the loads of neighboring houses that are served by the same line transformer. Many standby generators for home use come with a pre-wired transfer switch.
It is strongly recommended that all electrical connections be done by a licensed electrician. Depending on your local regulations, you may be required to get the installation approval by your electric utility. You may need this certificate if you later sell your house. If you are going to store a large fuel tank, you may also need to obtain a respective permit. The fuel pipe sizing, construction and layout must comply with NFPA 54 for natural gas and NFPA 58 for liquid propane applications.
WHERE TO BUY. Gensets are available direct from manufacturers, from authorized dealers, hardware stores, as well as online from independent retailers. Buying online has certain advantages, such as broader selection, lower prices, no sales tax in some states, and possibly free delivery to your home. Among reputable online places to buy at a discount I recommend this Home Improvement Department. It has the widest selection I've seen yet of Generac GUARDIAN®, Briggs & Stratton and other top ranking brands. And it offers free shipping on the gensets they carry. If you are looking for a small device, in this store you can order online and get a free pickup in a location near you. Note that with most manufacturers, you can usually order the installation and maintenance from their local authorized service provider regardless of the place of purchase, i.e. they would install it even if you bought it elsewhere. Of course, you can always hire your own contractor to do the installation.
Although a genset may be a relatively inexpensive way of supplying emergency power, it has certain disadvantages too. The main "cons" are noise, air pollutions and engine maintenance. If you prefer a silent, environmentally friendly and low-maintenance backup energy source, consider a battery-based system, such as solar-powered one.
Below you will find additional guides and reviews of residential gensets, safety recommendations and other facts you need to know. They will help you make an informed decision about the best emergency back up generator for home use.
SELECTION GUIDES AND REVIEWS OF HOME GENERATORS
Electric generators for home use - a consumer buying guide with facts, reference information and selection advice.
Consumer Reports emergency power buyer's guide: overview, wattage requirements and ratings.
THE BASICS OF EMERGENCY BACKUP POWER FOR THE HOME and OWNER's REFERENCE
How emergency backup power systems works.
Standby genset for emergency use- general information, sizing, NEC® installation requirements, tips.
Generating set installation guide- unloading, installing, starting.
| Backup Power
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| Ratings: portable
| Ratings: standby
| Transfer switches
| How To Buy
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