Generator stored outdoors?

tom_nwnj(z6 NJ)October 31, 2011

I need to make a decision on getting a generator, backup // standby, whatever. The largest backup I have found is 17.5K continuous, pretty good size.

The price is OK, don't need propane permits, etc. Good Good.

I would like to store it outside, under my deck. I can vent it OK, when running.

I was thinking about mounting it on the types of pads that heat pumps sit on, and a roof of corrugated fiberglass or galvanized steel. It will not get rained on.

My only concern would be that dampness will shorten the life. Any comments, or stories about successfully storing expensive small engine tool out of doors?


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Well, i have seen generator sets installed inside of homes, in the garage areas, and if done correctly, they can be made safe. BUT:
The exhaust from the engine must be vented outside, up, up, and away. You cannot just run a pipe out thru a window or a hole in the wall! The exhaust must be piped above the highest roof line, to be safe. Google the ideas on how to accomplish the job safely. There is a lot of good info to be had from various sites. Or seek professional help from those who install generators for power back-up settings. Old Joe, the handy-man from the local gin mill isn't who you want installing a gasoline or diesel powered generator in or near your home! Funerals cost MONEY! And, there's no sense in hastening your demise, by saving a few bucks, having Ol' Joe do it!

    Bookmark   October 31, 2011 at 10:43AM
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??? Most of the larger gensets I've seen, Generac is popular in this area, are designed to be put outside and have a weatherproof enclosure provided? Also in that size they usually have an automatic exercise function to start every week and run for a while. That would tend to get rid of humidity/dampness. Are you looking at one of those with auto transfer switch, auto starting, etc. OR just a large unit with a full tank of gas/diesel waiting for you to start it in a power outage?

Is the exhaust near a window that's usually open or something like that?


    Bookmark   November 2, 2011 at 12:34PM
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tom_nwnj(z6 NJ)

No, I mis-spoke. I am going to store a "portable" Generac out-of-doors. Actually, it is this one - Generac 5735 GP17500E 17.5K watts. I am going with the portable, mostly because the very permit rules for the standby generators (propane fired) are really too severe for me. I mentioned in an earlier post that the state inspectors would force me to put those steel and concrete polls around the propane tanks (industrial park look). My property, but that doesn't count anymore.

I am going to put the Generac on a plastic pad (same type you would place a heat pump on), and build a small corrugated roof over it. It will be stored under my ipe deck. My concerns are moisture from the ground while being stored there

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    Bookmark   November 3, 2011 at 4:33AM
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IMO yes, anything stored outside where wind, rain, and snow can be blown in will shorten it's life. If i paid that much for that big gen. I would build vented Brick SH around it to protect my investment.

    Bookmark   November 3, 2011 at 9:09PM
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tom_nwnj(z6 NJ)

Thanks for that rcmoser. I am going to build something around it, just not sure how large a project it needs to be.

    Bookmark   November 4, 2011 at 7:51AM
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Why not see if Generac has a enclosure that you can do a "store in place" type of thing. When you start "scratch" building it gets pricey, real fast.

Good Luck,


    Bookmark   November 4, 2011 at 2:15PM
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tom_nwnj(z6 NJ)

exmar, no Generac doesn't make anything for that. The fella there said if I want to store out-of-doors, get a propane fired one. As mentioned, not going to do that.

Seems the pads that Heat Pumps sit on would be good for under the generator. Keeps the moisture from coming up.
Thinking of making some kind of crate cover for the machine. Hook it to the plastic pad underneath. Just have to keep the crate light-weight. That should keep the machine fairly dry.

    Bookmark   November 4, 2011 at 4:24PM
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Hmmm, Why don't you get the unit with wheels and have the wiring ready at the location with or without a pad to sit on and store inside?

Small engines of this type require a lot of air for combustion and COOLING, plus a good sized exhaust port. Something almost like a roof with four posts to hold it up. Alternately, you could put an enclosure with an exhaust fan and large intake port for air. All those holes in your enclosure=lots of areas for moisture, snow, etc. to come in on your new genset. Not to mention mice, bees, and other kritters who just love man made abodes. Bees are a nuisance, but mice can literally destroy an engine, see the posts in Tool Shed and Lawn and Garden Tractor forums.

Another consideration is theft, that's an expensive unit you're going to have sitting outside, albeit under the deck, but folks have a way of noticing these things...:-(

I keep mine in the barn and when needed roll it onto the front porch, wirinig is waiting (hidden when not needed.)

Whatever you do, make sure you have a separate ground for the genset!! Lots of folks forget that point.

Interesting concept.

Keep us informed as it develops.

Good luck,


    Bookmark   November 7, 2011 at 7:24AM
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stinkytiger(z5 - z6)

Hi Tom,

That NJ snow storm in Oct 2011 was bad. If you are looking for a backup genset solution in the 17Kw range then a Natural Gas / propane set is the solution. Petrol ones will go up to maybe 7kw.

In general at the 17 kw range, there are two broad types of genset. A. Lawn mower engine types and B. Car engine types. The lawn mower engine types are cheaper to purchase and cheaper to install. All in this savings can be about 30 to 50%. The lawn mower engine types are usually installed on a Gravel base. Car engine gensets need a concrete base and heavy lift, e.g. crane or hydralic back hoe because the weight is much more.

Gravel base is usual specified because it allows water to drain, provides a firm foundation, and is fire proof. Most propane standby gensets typically come with an enclosure and matching auto switch transfer switch.

My neighbour was quoted in New York State $US 14,000 for a turn key installation. That included a propane tank, trenching, all work permits and wiring.

In general propane sets of the size you are interested in require permits. The siting of the genset will need to be dry-ish, away from floodng areas, well ventilated and away from the house maybe 3 to four feet.

If you want to go for the top product then you may want to consider Cummings Onan (See Costco for a cheaper source of Cummings Onan), Kohler, Ingersoll Rand. These supply eqipment to airports, prisions etc. They are however priced accordingly.

Best, Mike.

    Bookmark   November 18, 2011 at 3:14PM
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Re your original post; my 7k generator seems to be ok after 5 years under my front/side porch with roof. It runs fine and doesn't show deterioration.

No one has asked why you want such a large unit. My 7k unit from COSTCO will run almost anything I would need under emergency conditions. I can run one home AC unit although I use it in moderation. If I realized that extended use was likely, I would moderate further still.

It seems to me that the real problem for extended use is consumption and STORAGE of gas for the generator. I keep 15 gals around and use (rotate) it for all small engine use. The 17k unit suggests rapid gas consumption with the need of more fuel.

    Bookmark   November 19, 2011 at 7:37AM
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