Client would like a shed built to contain his generator; he lives on the coast and the salt air rusted his last generator to a pile of corroded dust. I’ve yet to talk to the Building inspector about any particulars he might have. My current idea is to build the shed with screened louvers in the lower end walls for ventilation. The electrical connection (he wants it to auto start on loss of power) is to be handled by his electrician. The shed location is about 2 feet from the main house, ~8 feet from the lpg tanks, and the ridge of the shed roof will be connected to a deck rim joist.
Any one ever build one before, or have any thoughts? I’m leaning toward lining the inside with CBU to minimize flammability. Not sure about the exhaust, should it go out the roof, or wall? And who would make up the pipe if ducted outside?
Still in the planning stage, though he’s been waiting patiently for a few months already.
Gotta admit I’ve never built an enclosure for a generator before, so any help would be appreciated. Thanks.
Replies
salt air rusted his last generator to a pile of corroded dust
What size are we talking here?
Sounds like an aluminum block engine or suptin' under 5-10 kw? to corrode.
More details needed, generator mfg, size, etc. A 5 kW HD generator probably isn't worth building a shed over.
Friend at work has a diesel 20 kW gen. -- in a metal enclosure on Whidbey Is. in WA state, no problems, but he is not right on Puget Sound.
Go by your local Cat dealer and take a look at the big Cat gen enclosures to see what is typical .
The generator will probably be (I will buy the replacement after the enclosure is built) a Honda air cooled 5kw.
I know it's a little odd, but the older gentleman wants his emergency power, wants it enclosed, and wants it to auto start. And he can afford pretty much whatever he wants (he lives alone in a 20 yo house on the shore that must be close to 7500 ft2 with an elevator, and used to have a pool in the basement. Moisture killed that idea.)
And he wants it to blend in to the existing structure. I'm just trying to sort out the building details.
I tried to sell him on the self-enclosed units you just drop down and wire up, but he seems determined to throw his money my way, so I've agreed to do drum up a proposal.
Thanks.I never met a tool I didn't like!
I am building a CMU structure now that functions as a retaining wall and will house a propane fired boiler and generator about 20' from the house. I wanted to eliminate combustible gases from occupied spaces, reduce salt air corrosion, and isolate noise. We filled the block yesterday.
I will use a 15KW air-cooled generator with a 14x20" louvered port for the generator's combustion air intake air supply for the shed. A sealed duct for the outlet cooling air from the generator will be connected to a higher louvered port. The exhaust will be piped separately. The boiler has a concentric PVC exhaust/intake pipe that will go through the shed roof.
One key to controlling salt air corrosion is keeping the metal you want to protect from being cooler that the ambient air. This significantly reduces condensation of sodium laden water on your stuff. For this reason, it is preferable to protect your intake vents from wind and place it on the opposite side of the structure from the ocean. It is also desirable to have a heat producing component in the same structure.
I will be installing a 15w heating element called a damp-chaser inside the generator's housing to keep it a bit warmer than the surrounding air. It will not be wired to standby power so it will not be running when the generator is. The sound insulation in the generator housing should make a 15w heat source adequate.
Edited 4/16/2005 12:18 pm ET by CJD
I built an enclosure for my 5kw generator, mostly for noise control as we developed the property. A couple of important facts:
- 5kw is a small genset. I hope he doesn't expect to run much more than a fridge, a few lights, and a small number of plugs.
- Cooling. An air cooled unit relies on a lot of air movement, either from the wind or by convection. Even if you provide openable sides or doors, the auto-start thing worries me because there may be no one around to open them. At best it will greatly shorten the life of the motor; at worst it could constitute a severe fire hazard.
Scott.
Definitely check and double-check with the AHJ to make sure you have required setback from the house, then add a little more just to be sure. Keep in mind that you have exhaust, fire, and fuel leakage as potential life hazards to the house inhabitants, and all three need to meet code and also satisfy common sense.
Exhaust out the top will keep the hot exhaust away from fingers, etc, but be sure it's OK with the genset mfgr, and make sure there's a rain hood of some sort.
You also need to plan the flow of cooling air. Again, the mfgr will have something to say. Probably the best approach would be a louvered electric fan (eg, livestock shed fan) set into the wall, set up to come on when the genset starts. Passive louvers on the other side exhaust the air.
Try to plan the structure & the exhaust positioning to minimize noise in the directions that matter.
I agree that a 5kw generator is really small, particularly if he has a 7500 square foot house with an elevator...most likely he has a lot of electrical loads in that place. A generator needs to be sized to allow for the starting current of all the motors it will be operating plus lights, heat, etc. It would be a good idea to give the generator supplier a list of everything he wants to run off it, and they should be able to size it properly.
I also agree with the idea of a fan with powered intake and exhaust louvers that come on with the generator to provide combustion and cooling air. When it's not running they'll be closed and will help keep the weather out. The building should be at least large enough that a person can get inside and comfortably work on the genset if needed.
A permanently installed standby generator should have means to keep the engine warm all the time, plus a battery charger to keep the battery ready to go. On a larger generator a block heater would make sense, in your case the small heater you mentioned will probably work OK. It should also be exercised periodically, once every two weeks or once a month maybe, to keep it in good shape. He'll need to remember to service it regularly as well, change oil and all that. The automatic transfer switch should have provisions to automatically exercise the generator, but as far as servicing it he may want to get a service contract with the generator supplier.
A unit that small will probably be gasoline powered. If he goes with something larger natural gas would be a good choice if it's available onsite, otherwise a diesel will probably be more durable and long lasting.
Nick,
Dont know the construction you are working with, but a good friend of mine who happens to be an electrician has his genset in his basement. All you need is combustion air in, and exhaust pipe out and it should never rust. I dont think cooling would be a problem. Just an option to think about.
Bill Koustenis
Advanced Automotive Machine
Waldorf Md
This isn't legal (without a "vault") in most jurisdictions, due primarily to the hazards of a leaky exhaust. Furnaces don't make much CO unless very poorly adjusted, but IC engines put out a lot of CO, plus substantial amounts of NOx. It doesn't take a large exhaust leak to cause problems.
And exactly how far from the salt air is the enclosure going to be? I would think salt air is salt air, whether there's a roof or not.
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Sojourners: Christians for Justice and Peace
True enough, can't get rid of the salt air, but you can minimize the effects of moisture by getting the thing out of the rain and snow.
I never met a tool I didn't like!