Standby generator - recommend source?

[BlueRidge]

It's time. I'm getting a standby generator before I need it. I hope. Anyone recommend a source? I'd PREFER diesel, but I'll take what I can afford.


Which ain't much! [img]/forums/images/icons/grin.gif[/img]

[GaryM]

I bought my Generac unit from the Electric Generator Store. They carry several brands, both portable and permenantly installed.

http://store.yahoo.com/generator-store/index.html

I ordered my unit and it was shipped by truck right to my door.

[Pat]

Blue, How often and how long does your area suffer outages in general? Diesel is a great choice for long runs but LPG or natural gas is a better solution for short to moderate outages. Gasoline with fuel stabilizer is a cheaper solution than diesel but still not as nice as LPG or natural gas.

Short runs aren't diesel friendly and gasoline isn't much better. LPG and natural are super clean and the weekly short test runs don't cause problems. There are LPG conversions for a lot of gasoline fired rigs. The genny in my RV was built to be a gasoline unit but was converted to LPG prior to installation.

If you have never serviced an LPG or natural powered internal combustion engine then you are in for quite a surprise. They stay super clean. The oil hardly discolors. They don't make sulphur based acids out of exhaust components. Spark plugs stay very clean.

I'm not knocking diesel. I love diesel! It is just that diesel is not as well suited for standby generators in typical home owner service. Diesel is MORE expensive to buy and maintain too in this application of short runs. If you were going off grid and needed to run the genny a lot as primary power source or as part of a solar/wind/battery system then diesel is likely choice #1.

[img]/forums/images/icons/smile.gif[/img] Pat [img]/forums/images/icons/smile.gif[/img]

[JoeR]

Pat,

Besides LP running clean, can you elaborate on why diesel is not good for short runs? What do you define as a short outage? I am just curious and trying to learn.

Thanks,

Joe

[Pat]

Joe, In general short runs of internal combustion engines introduce moisture into the crankcase where it can combine with other chemicals present or introduced. Long runs bring the engine up to temp and hold it there for a suficient period to "dry" out the engine and minimize the formation of acids and such undesirable reactions.

In the case of natural gas or propane the chief chemicals produced are carbon dioxide and water. Not so hard on the engine if not eliminated by a longer "warmer" run. With diesels there are several other possibilities among which are sulphur compounds. You will end up with sulphurous and sulphuric acids (and I don't know what all else in a water solution (from moisture produced by combustion but not driven off by sufficient high temps over time.)

These undesirable compounds eat away at engine parts and attack the lubricating properties of your crankcase oil. The additive "package" in your oil is supposed to help prevent this but the additives may be prematurely exhausted in this "severe service" regime. A lot of short runs are very much harder on the equipment than a few significant long runs. This is why someone who only drives long distances will typically get to see more trouble free hundreds of thousands of miles as compared to the "little old lady" who only drives her car on Sunday a quarter of a mile at a time (at the drags!)

You mentioned sensitivity to initial cost. Lifecycle cost is more imporatnt. How much will it cost you to buy the genny, operate it, and maintain it over its useful life. The diesel costs significantly more to buy and in some classes of service it pays this back in longer life, better fuel economy, and so forth BUT IN ONLY CERTAIN CLASSES OF SERVICE.

Unless you anticipate a lot of quite long electric outages it is unlikely that the "best" solution is a diesel. If you were a hospital or a radio station or the like and needed well over 20 KVA then a diesel would likely become the "best" choice.

I'm sure there are other sources of opinions that will make a better case for a "small" infrequently used diesel but do the math and be guided by reality not preconception.

[img]/forums/images/icons/smile.gif[/img] [img]/forums/images/icons/smile.gif[/img] Pat [img]/forums/images/icons/smile.gif[/img] [img]/forums/images/icons/smile.gif[/img]

[Pat]

Joe, I just realized even after all I said I didn't answer one of your questions... How long is a short generator run? In the context of this discussion a short run would be one where the engine does not get up to and maintain normal operating temperature for a period of time sufficient to thoroughly dry out the engine's innards. Something like an hour and a half maybe...(anyone have wide experience here???) it depends on the specifics of the particular installation.

The thing is that you will not know in advance how long an outage will be so do you start the genny or wait to see if power will be restored? (assuming manual system) How long do you wait? OK, lets say you wait for an hour then start the genny and the power comes back on 10 minutes later. What to do? Maybe run the genny for 2 hours to "dry it out?" What if you start the genny right away when power fails and 10 min later power is restored? If your system is automatic it might be able to be programed for a minimum run time to satisfy the prevention of short runs.

Systems we used at Ft. Irwin NTC waited 5 min to start and ran for a minimum of an hour to avoid multiple starts and stops since often there are "clusters" of outages of medium to short duration. We were fighting lightning storms not ice storms, or wind damage. OUr needs were not your typical residential concerns. Our equipment was running all the time on huge banks of NiCad batteries and commercial power ran battery chargers. So when commercial power went down our computer center and other equip didn't know it. It was equivalent to a giant UPS.

Remember I am quite a fan of diesel power but diesel isn't always the best fit for a specific situation. I think a residential standby generator, auto or manual, would be best served by 1. natural or LPG, 2, gasoline, and 3. diesel. If power outages are more often of several days duration or run to weeks then diesel would be a good choice. In that instance the premium you pay for the diesel engine might be more likely to be amortized. An emotionless lifecycle cost analysis will tell ou where the economy is or what outage statistics would have to be extant to make a diesel breakeven compared to LPG.

[img]/forums/images/icons/smile.gif[/img] [img]/forums/images/icons/smile.gif[/img] Pat [img]/forums/images/icons/smile.gif[/img] [img]/forums/images/icons/smile.gif[/img]

[Bird]

</font><blockquote><font class="small">In reply to:</font><hr />
Something like an hour and a half maybe...(anyone have wide experience here???)

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I wouldn't say exactly "wide experience" but when I was commander of the police communications and the building (Dallas City Hall with the police and fire communcations center in the basement) had a couple of monstrous diesel generators, we killed the power to the building and ran everything on those generators for an hour every Sunday morning; i.e., ran them under load for an hour.

And when I had a 4.5 kw LPG generator in the fifth-wheel trailer we were living in, I tried to run it under load for an hour at least every two weeks and the same with a 7 kw gasoline generator in the motorhome when we were living in it.

[CJDave]

[img]/forums/images/icons/tongue.gif[/img] Pat has given you about as good a synopsis on standby power units as you could possibly want. [img]/forums/images/icons/smile.gif[/img] As long as we are doing it, I'll add my two cents worth as well. [img]/forums/images/icons/smile.gif[/img] I spent the last thirteen years doing generator tests for all types of facilities who depend on emergency power for absolutely, positively, no-fail backup to their normal utility system power. As the Chief told you, they usually run an hour a week in order to keep them "fresh". Often they have an artificial "load bank" that can be cut in to help load up the system and make the engine grunt a little to get rid of that moisture that Pat mentioned. [img]/forums/images/icons/tongue.gif[/img] If it wuz up to me, I would go with LPG, and 1800 RPM. The LP engines start easier so there are fewer battery issues, and LP stores better than gas or diesel. Yes, I KNOW that 1800 RPM doesn't follow the load as well as 3600 on the smaller units, but the reduction in noise and wear will still be worth it. [img]/forums/images/icons/tongue.gif[/img] As far as I am concerned, the BEST engine for following changing electrical load is the sixteen-cylinder 16V-71 Detroit. Now THERE, Buddy, is an engine that you can really play "engine room" with. Have some good ear muffs ready! [img]/forums/images/icons/crazy.gif[/img]

[Bird]

</font><blockquote><font class="small">In reply to:</font><hr />
sixteen-cylinder 16V-71 Detroit. Now THERE, Buddy, is an engine that you can really play "engine room" with. Have some good ear muffs ready!

[/ QUOTE ]

Dave, that sounds even bigger than the two the city hall has. I don't remember all the specs that I was familiar with when they were installed 29 years ago, but I know they were BIG Caterpillar engines (V-12?), dual exhaust of course, with water cooled mufflers, and as you said, we had ear muffs hanging just outside the generator room. You didn't even open that door without hearing protection. I don't remember what the fuel consumption was, but I do remember they were pulling from a 10,000 gallon diesel tank.

[GaryM]

My Generac unit is 3600 RPM. It's not too bad in the noise department. The sound of the air conditioning and TV can cover it up just fine. [img]/forums/images/icons/smile.gif[/img] It exercises itself once a week for about 12 minutes. Not under load though. It's load tested about once a month when the commercial power goes out.

I didn't have the extra money for a lower RPM unit. And the propane runs nice and clean as you said.

Where I work, Boeing in STL, we have at least two big gensets. One runs our Emergency Operations Center. The engine is a really big diesel. At least 10 cyl perhaps more. Never heard it run. It's in a basement room with big air intakes and as was mentioned a water cooled exhause.

The other is a CAT unit that's located in a purpose built shelter. It's designed to carry the load of our computer server bank. Batteries and inverter carry the load until the generator takes over.