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Onan Enclosure Thoughts - 6.5NH


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  #1  
Old 03-12-2017, 12:20:38 AM
AppleTech AppleTech is offline
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Default Onan Enclosure Thoughts - 6.5NH

So I'm very nearly finishing the rebuild of my new 6.5NH. Muffler should be fabbed up and installed this week and then I'm going to go about getting it mounted and connected.

I'm starting to think about an enclosure. For cost (copper is expensive) the unit will probably be within 10 feet of the home. Exhaust will be exiting right next to Vacu-flow exit and pointing AWAY from the house so I'm thinking that we should be safe from any CO poisoning via the eaves. (it is a very tall 2 story house so even 10 feet might be overkill).

I'm looking at budget friendly options. I likely will be putting something on a wood-framed gravel pad to start (might do a concrete slab in the future). I'm considering building something out of plywood and painting with a fire-proofing agent just to be safe. I'm not sure how exhaust can be safely routed through a wood enclosure though? Maybe a large chicken-wire opening for the vacuflow and muffler to exit within a few inches of it? Trying to avoid trapping too much exhaust heat in the enclosure.

Is wood just stupid? Are there better options? I've seen those suncast/rubbermaid solutions but I don't know how well those work out for anyone. I realize obviously I'm going to be putting intake vents as well (probably a full side of intake vents at the generator end to assist in fresh intake to the vacuflow).

Would love some thoughts/pictures that you all have - I searched a bit but didn't find anything quite specific on this topic.
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Old 03-12-2017, 01:49:57 AM
Ray Lynch Ray Lynch is offline
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Default Re: Enclosure Thoughts - 6.5NH

See posts #24, 25 and 26 in attached link for what I did for my JB.

Ray

https://www.smokstak.com/forum/showt...=140244&page=2
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Old 03-12-2017, 10:04:05 AM
AppleTech AppleTech is offline
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Default Re: Enclosure Thoughts - 6.5NH

Thanks Ray - your first run enclosure looks along the lines of what I wanted to build as a quick start - we are fast approaching what I think will be a very stormy spring here in TN and I'd like to get this set up in the next weekend or two.

Couple questions - what did you use for the sides and where did you source it? Is it plywood with cutouts for the vents or are they fully vented panels? How was the noise management with this enclosure?
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Old 03-12-2017, 11:11:42 AM
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Billy J Shafer Billy J Shafer is offline
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Default Re: Enclosure Thoughts - 6.5NH

With an NH the noise shouldn't be a problem to keep down. For the exhaust going through wood. You can get thimbles for stove pipe thru wood. The main thing is to give it plenty of cooling air and make it easy to service. Ray has a very good install. You should be ok with the house and exhaust. I believe the required space is eight feet.
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Old 03-12-2017, 11:28:13 AM
Kevin K Kevin K is offline
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Default Re: Enclosure Thoughts - 6.5NH

While the "Gold Standard" generator housing is a 10x10 or 12x12 wooden shed like Leon has for his JB, a doghouse style enclosure can also be used. A wooden shed has the advantage of keeping the generator temperature above the surrounding air temperature at night, and prevents condensation and rust from forming on the generator. On the other hand, there is the problem of safely routing the exhaust through the flammable wooden wall , which can be accomplished by using a small thimble made for a wood stove flue pipe.

I would consider raising the enclosure two feet above ground level, with stacked cement blocks, legs, or a stand of stacked 6x6 pressure treated timber filled with crushed stone. Here in the Northeast, it is not uncommon to have a two foot deep coating of snow on the ground, and you don't want to dig the generator out before you use it. A raised generator shed also keeps it out of the splash zone during a rain storm, and above ground level in case of a flood. Your back will thank you because you don't need to bend over or lie on the ground to service it. Raising it may also help with rodent incursion issues.

If you have an inherently regulated generator like the NH, the output voltage is a function of engine speed. Because of governor droop, the speed will typically range from 62Hz no load to 58 or 59 Hz full load, and consequently the voltage under full load is typically on the order of 110VAC. This doesn't leave much room for voltage drop in the wiring to the house, so you may want to use a bit heavier wire to minimize voltage loss.
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Old 03-12-2017, 11:45:54 AM
Ray Lynch Ray Lynch is offline
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Default Re: Enclosure Thoughts - 6.5NH

Quote:
Originally Posted by AppleTech View Post
Thanks Ray - your first run enclosure looks along the lines of what I wanted to build as a quick start - we are fast approaching what I think will be a very stormy spring here in TN and I'd like to get this set up in the next weekend or two.

Couple questions - what did you use for the sides and where did you source it? Is it plywood with cutouts for the vents or are they fully vented panels? How was the noise management with this enclosure?
Three of the sides are 1/2" pt plywood that I cut for the vents. The vents are from Lowes. The 4th side where the muffler exits is made from 2 metal closet doors that I got from CL and cut down. This 4th metal side is shown in the pics for the 2nd enclosure.
The roof is metal. The roof frame is metal studs.
The noise level is similar to my 12.5 HP ride on mower.
I know wiring and trenching are $ and work but get it as far from your house as practical.
Exhaust fumes have a way of finding the inside of your house under the right conditions.
Good luck.
Ray
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Old 03-12-2017, 02:20:48 PM
len k len k is offline
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Default Re: Enclosure Thoughts - 6.5NH

Looking at mud splashed up on stuff looks splash zone from rain extends 2 - 2.5 ft up from ground. So I'ld consider vent louvers inside the enclosure also, aimed so as up going splash comes thru outer louver it hits backside of internal louver instead of gen. Saw a GE gen at home Depot recently, it's air intake vents are at top, on under side of overhanging cover. About 2.5 ft up.

Good to have space between enclosure and gen so if snow makes it thru enclosure vents then it has someplace to go before it clogs the gen cooling intakes. This is another good reason to raise the gen

If you use wood or plastic for enclosure walls there are fire code rules for min distance to combustibles.
Gut feeling is plastic will warp up from heat.

Gens on ground without a slab , I'ld put some type of moisture barrier under gen to prevent moisture from coming up from the ground and making high humidity in the gen enclosure. Humidity leads to condensation on the gen.

I like the gravel under the gen , they say mice don't like walking on it. But I suspect won't make much difference for such a short walk. Plus can lose carb parts in it. Maybe place gravel around the enclosure, if tree leaves won't cover it over in a few years.

I would say if house is taller ( 2 story vs 1) then gen should be further away from house, (possibility of CO making it to 2nd floor). Not sure, here I think code says 10 ft from gen to building. Rules about distances from exhaust to windows too.

I do like Leon's shed, makes for a warm place out of wind to work on gen if it won't start during outage. Plus should get no condensation if you close off vents when not in use.

Last edited by len k; 03-12-2017 at 03:16:17 PM.
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Old 03-12-2017, 09:02:30 PM
AppleTech AppleTech is offline
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Default Re: Enclosure Thoughts - 6.5NH

I ran across this on Craigslist. All-aluminum enclosure for $200. Surely more expensive than building one from plywood although it would save me lots of time. Looks to be already insulated, although I'm guessing not fire rated.

https://nashville.craigslist.org/mat/6026744552.html
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Old 03-12-2017, 10:48:33 PM
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Default Re: Enclosure Thoughts - 6.5NH

Quote:
Originally Posted by AppleTech View Post
I ran across this on Craigslist. All-aluminum enclosure for $200. Surely more expensive than building one from plywood although it would save me lots of time. Looks to be already insulated, although I'm guessing not fire rated.

https://nashville.craigslist.org/mat/6026744552.html
Their full site is here gcenclosures.com. Having issues with emails going through but I'm going to call them tomorrow and see if they offer any units sans insulation so I could install my own of the proper spec.
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Old 03-12-2017, 11:24:03 PM
Vanman Vanman is offline
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Default Re: Enclosure Thoughts - 6.5NH

Wow, that's looks like a NICE enclosure!!
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Old 03-13-2017, 01:07:12 AM
len k len k is offline
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Default Re: Enclosure Thoughts - 6.5NH

Check if exposed Styrofoam. would need to be at least covered by metal foil. Maybe more , I don't know fire code
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Old 03-13-2017, 01:36:18 AM
Vanman Vanman is offline
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Default Re: Enclosure Thoughts - 6.5NH

As said it was foil faced. Obviously you would still need a thimble for the exhaust, but so would you for wood. I can't see it being a problem, so long as no exhaust components were close to it. (Radiant heat).
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Old 03-13-2017, 07:49:23 AM
dmeed dmeed is offline
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Default Re: Enclosure Thoughts - 6.5NH

The ad mentions foil faced poly isocyanurate foam which is a bit different animal that styrofoam. Maybe (emphasize _maybe_) fire retardant or fire resistant - check on it. I know solar panel construction calls for that foam because it stands up to the high temperatures in solar panels where the extruded stuff melts.

David m
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Old 03-13-2017, 08:28:25 AM
PopsGarage PopsGarage is offline
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Default Re: Enclosure Thoughts - 6.5NH

Nice enclosure I cant build one for that price.

Bob
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Old 03-13-2017, 11:59:44 AM
willie1959 willie1959 is offline
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Default Re: Onan Enclosure Thoughts - 6.5NH

Use drywall for sound two layers cheap works great. A 2x4 frame wall with 3/4 plywood exterior , 3 1/2 fiberglass batt insulation and two layers of drywall is good for 45 db sound level reduction. I use a sound meter less than 50db at 10 feet from generator

only thing better are cement blocks for sound

for exhaust 15 foot stack up
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Old 03-13-2017, 12:32:14 PM
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Default Re: Onan Enclosure Thoughts - 6.5NH

How about a double stud frame wall, with the inner and outer studs staggered with insulation between all of the studs. Double 5/8" drywall on the inside, the 3/4 ply on the outside. Then the vibration from the inner wall cannot couple to the outer wall.
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Old 03-13-2017, 01:06:44 PM
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Default Re: Onan Enclosure Thoughts - 6.5NH

that's the best just trying to keep costs down
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Old 03-13-2017, 02:12:36 PM
Max Thompson Max Thompson is offline
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Default Re: Onan Enclosure Thoughts - 6.5NH

Those are back flow encloses.

I would be amazed if you could buy one from the manufacture for the $200 price in the ad. Would have to assume someone is selling surplus from a job.

There would likely be no fire retardant material in it. It is designed for water piping inside only.
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Old 03-13-2017, 02:20:39 PM
Kevin K Kevin K is offline
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Default Re: Onan Enclosure Thoughts - 6.5NH

While 3/4" PT plywood, double stud walls, 3.5" fiberglass insulation, and two layers of sheetrock are great ideas for a 10x10 shed, they are just not doable on a doghouse style generator house. The problem of access to the generator for maintenance makes these construction methods impractical. Well... I guess I could use a front end loader to lift the entire house away from the generator and base, but I don't consider that easy access.

If you could indeed purchase the aluminum enclosure for $200, I would jump on it.
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Old 03-13-2017, 02:34:32 PM
LRomero LRomero is offline
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Default Re: Onan Enclosure Thoughts - 6.5NH

I agree, the aluminum enclosure for $200 is a steal. I would jump on that in a heartbeat and wish I could find something like that in my area at that price.
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