The Cooperative Difference E-Bill
FAQs on Generators
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This depends on the number and size of loads you want to run at the same time. If a house uses natural gas (or propane) for heat and hot water, a 4,000 to 6,000 watt generator can maintain a high level of comfort (assuming natural gas or propane is available). A house using an electric furnace and electric water heater may need a generator in the 20,000 to 35,000 watt range. Generator size can be estimated by determining the major loads to be supplied and allowing some overhead for convenience appliances (television, computer, etc.). Some of the most common major loads are listed below (these are average numbers and can vary):
A manual transfer switch is a panel wired into the house electrical distribution system that allows a generator to be used to supply power. It prevents the generator from back feeding the utility and reduces the potential for lineman injury.
The simplest and lowest cost method is to run extension cords from the generator to the loads to be supplied. If the generator is to be connected to household wiring, an approved method of isolating the house electrical system from utility must be used. A manual or automatic transfer switch can be wired into the distribution system to allow the use of existing household wiring and receptacles. A three position, whole service disconnect (knife switch) can also be used to isolate the house electrical system from the utility.
No. However, if the generator is to be connected to the house electrical system, an approved means of isolating the house from utility power is required. This is to prevent the generator from back feeding the utility and injuring the line workers that are trying to restore power. Significant damage can result from the generator being on line when utility power is restored.
This can vary depending on many factors. Typical installations can start at $400 to $800 for a surface mounted switch located near the main distribution panel. Most transfer switches come with clear documentation and can be installed by the owner in about two hours for the cost of a permit. Some factors affecting cost include:
No. In concept this may seem like a good idea, but is not advisable for the following reasons:
Yes. Most utilities maintain this type of information and make it available to the line workers that will be working in the area. Power restoration can be delayed while line workers check to see if a generator is being properly used. Having this information beforehand can reduce these delays.
This depends on many factors - shelf life, cost, storage location, availability, etc. See What are the advantages and disadvantages of the different fuel types? below for more information on the different fuels.
No. Converting the Onan portable generators to propane is a one way conversion. The carburetor float and choke assembly are removed, the mixing chamber modified, and the gasoline supply line removed during the conversion. The fuel tank is left on the unit to maintain its appearance and to provide some weather protection during outdoor use.
That depends on two factors. Larger tanks offer longer run times between refueling, and on site delivery of fuel may be available for tanks larger than 100 gallons. Small tanks like those used on barbecue grills allow several hours of operation and are easy to transport for filling at fuel stations.
Yes, with some minor modifications. The natural gas quick disconnect fitting on the hose will need to be removed and replaced with a propane pressure regulator and tank fitting. The air-fuel mixing valve will need to be adjusted for proper operation (or backfiring will result). Engine speed will need to be adjusted to provide proper output frequency.
No. Onan does not produce a propane or natural gas generator kit. Instead, the generators are converted at a Cummins Northwest facility. This is a program researched and developed by Cummins Northwest. The original warranty will still be honored, and failures resulting from the conversion will be backed by Cummins Northwest as if they were covered by the original warranty. Controlling the quality of the conversions allows us to ensure that all conversions are performed the same way to simplify future repairs and reduce the possibility of failure.
This depends on the size of the tank and amount of load on the generator. Higher loads require more fuel. A 6000E portable will run for 9 hours at rated load. A 5000E portable will run for 11 hours at rated load, and a 4000E will run for 13 hours at rated load. Many users average 10 to 15 hours on a 6000E under normal usage. A conservative rule of thumb is one gallon of fuel per hour for a 5,000 watt generator. Propane fueled portables use a slightly larger amount of fuel than their gasoline counterparts.
Unfortunately there is no set answer for this question. The Onan portables are designed for long life, heavy duty operation, and long run times. Gasoline units should be shut down during refueling to reduce the potential for starting a fire by spilling gasoline on hot exhaust components. The oil level should be checked and the unit inspected for signs of fatigue or abnormalities (cracked receptacles, etc.) before restarting. One of the advantages of natural gas and large propane tanks is the longer run time between refueling. However, the generator should still be periodically shut down, the oil level checked, and the unit physically inspected. The Onan portables have low oil pressure protection, but frequently checking the oil level will help spot excessive oil consumption problems early.
The answer to this question is similar to How long will a generator run on a tank of fuel?. The generator should be shut down and inspected daily or when refueling. If long periods of no load or light load operation are expected (such as during the night when everyone is sleeping), the generator could be shut down to extend the useful life of the generator and reduce fuel costs.
No. Some of the most important features of a portable generator are size and weight. Diesel engines typically weigh more and are physically larger than their gasoline counterparts. Another important factor is cost. Small air cooled gasoline engines are used in many more applications than small air cooled diesel engines. This helps to reduce the cost of the engine, lowering the cost of the portable generator.
No. A 10,000 watt generator requires a larger generator and engine than a 6,000 watt generator. In order to keep the size and weight of a 10,000 watt generator at a manageable level, it is necessary to use the smallest engine and lightest components. This can reduce the useable lifetime and reliability of the product. Unlike other portable generator manufacturers, Onan produces generators from 2,000 watts to several megawatts. If a customer is looking for that level of power output, it may be beneficial to consider switching to a full fledged standby unit. If cost is a driving factor, carefully reviewing the loads to be supplied may show that a 6,000 watt unit is capable of doing the job with some basic load management.
The Onan portables are designed for heavy duty commercial use, where long life and reliability are very important. To meet these objectives, it is necessary to use only the best components, which does raise the cost of the product. This also allows Onan to provide the longest warranty available for portable generators (3 years) and the option to purchase two years of additional warranty at a reasonable retail cost of $75.
Approximately 79 dBA at 7 meters at rated load. Average noise levels are usually in the 75 dBA range.
Most portable generators use an air cooled engine operating at 3600 RPM with little or no noise attenuation features. Engines of the same horsepower will produce roughly the same noise level. Onan portable generators use a larger engine for a given wattage than most other generator manufacturers. This increases the life of the product, but does produce slightly more noise. Normally this noise difference is negligible, and the increased product life is worth the trade-off. There are portable generators with sound attenuation features that are quieter than their non-attenuated counterparts. These units are usually more expensive and may trade-off a lower noise level for other important features.
Installing panels around the generator to reduce noise levels is not advisable. The engine is air cooled, and restricting the access of cool air to the engine will reduce the life of the engine. Placing a barrier between you and the noise can deflect a majority of the high frequency noise and reduce noise levels. A simple sand-filled cinder block wall the height of the generator can significantly reduce noise levels (taking care not to reduce cooling airflow).
No. The addition of extra exhaust components does not significantly reduce the overall noise level of the unit.
Possible? Yes. Recommended? No. Adding additional components to the exhaust system can increase backpressure and does not significantly reduce noise levels.
Yes. Flexible exhaust extensions are available in many auto parts stores. Care should be taken to limit the length of the extension to minimize exhaust back pressure.
This is not recommended. Portable generators are designed for outdoor use. Running them indoors presents the following problems:
Yes, as long as the generator is taken out of the enclosure when operating it. Access to cooling air is vital to the proper operation of the engine. Portable generators do not have large cooling fans and are unable to circulate air in confined spaces. They rely on the natural circulation of heat resulting when the hot air rises away from the engine and is replaced by cool air.
How does the Onan portable generator compare to the lower cost generators in the home improvement stores?
Onan portable generators are designed for continuous heavy duty commercial use where long life and reliable operation is vital. This is accomplished by using proven manufacturing techniques and top quality components. Many corners could be cut to reduce the cost of the unit, but there would be a tradeoff in the life of the product. The Onan product is backed by the largest service and parts network in the area. Other manufacturers may require the product be sent back to them for repair which can take several weeks to perform.
The larger Onan home standby generators use liquid cooled engines that require belts, hoses, pumps, thermostats, etc. They are mounted on steel frames and come with weather protective enclosures. They have a more complex control system and have two-wire auto start capability. The warranty for the home standby generators covers travel time and mileage.
When starting loads on a portable generator, the larger loads should be started first. A 4,000 watt portable can easily start a one horsepower pump. The 5,000 watt and 6,000 watt generators are capable of starting up to a three horsepower pump.
No. The Onan portable generators use a manual, three-wire, start/stop system with no provision for automatic starter disconnect.