Since your fuel source is enclosed in a relatively small 75 or so cubic foot space, I think you should treat the exhaust as if it were in a hazardous environment, regardless of make up air volume, which would require an explosion proof exhaust fan. Additionally you may want to consider filtering your intake air to remove as much dirt and contamination from outside as possible which will prolong engine life and combustion efficiency.

 

Unless that is an automatic fire extinguisher, I would locate it away from the hut in case it's hot.

 

That is all good, but flammabe vapors are both heavier & lighter than air, meaning even with all the roof mounted vents it will not allow the flammable vapors to vent off fat the bottom- just like a water heater room, you must have venting 6" from the top & bottom.

 

Thats some Tim The Tool man stuff right there haha

 

Just remember, those fans are not rated for use where flammable vapors are or could be present (Class 1 Division 1 or 2 certified)....they will produce a spark or even a static charge which is more than enough to ignite accumulated vapors.

 

I paint cars for a living and that is a must!!!Ive heard crazy stories about guys blowing up their shops b/c of the wrong fans

 

Okay, just a catch-up. Thank you for the feedback... very much appreciated.

I ran the generator yesterday for an hour, with the load I intend to power with this fully on, and the inside temperature of the genshed hovered around 80 degrees, with the outside temperature only being 47. A 33 degree increase in temperature in a lot of BTU for sure, because the fan is sucking most of it out. I may close up the vents on the back of the shed and move them to the floor underneath the generator to encourage less trapping of heat. It might also be where I measured the heat which was in the far back corner opposite the side where the exhaust port is. This kind of stuff is not my forte (thermodynamics, airflow, et al) and I free admit that. I'm more of a monkey ;-)

The fan isn't stamped, certified or marked as an explosion proof fan however it's a synchronous motor which doesn't have brushes, so there's no sparks in the housing to ignite fuel vapor. Unless I'm missing something, that should be okay, right? Not necessarily from an "official" standpoint, but in concept at least?

Aside from the kinds of concerns you'all kindly pointed out, there is one design flaw on my part which didn't become apparent until yesterday - there's a skinny little tree about a foot away from the generator hut and it worked out the exhaust port blows right on that tree. So, the bark was cinged after an hour of running the generator. This surprised me because I figured the tree was a foot away most of the heat would spread out and not be focused on the tree, but apparently that wasn't the case. So tomorrow, the little tree goes. It's half-dead anyway. I just find it amusing that the exhaust port and the skinny tree truck lined up perfectly by accident. Figures, right?

I do think the intake ports aren't big enough though, because there's still enough suction to pull the doors closed tight if I close them. I can open them, there's not that much suction, but the left door has a slight warp in it because it got wet before I painted it, and that slight warp gets "sucked flat" so maybe instead of moving the intake ports I should just add another set on the bottom and call it a day.

I like the idea of filtering the intake air a bit as to keep debris and bugs out - certainly I want the generator to not be traumatized while operating it in the shed for durability reasons. Maybe I can use door screen material in a frame or possible sections of furnace filters or something like that. Whatever I end up using needs to stay put though.

A friend who looked at it a week ago suggested instead of having the generator suck in ambient air from inside the generator hut, maybe I should consider ducting from the air filter box in the center of the engine (v-twin) to the opposite wall of as to where the exhaust goes since it's right there, thus using the coolest air possible to feed the engine. That will require a little fangling since the airbox draws through large holes in the bottom, flows through the oval filter, then into the throat of the two barrel carb. This makes sense since the measured temperature inside is hotter than outside.

Thanks again!

 

With regards to the fan, because of the materials the fan blade itself are constructed of, that will produce more than enough static charge to provide a substantial ignition source. Even if the motor has no brushes, etc, all of the wiring connection points are considered "exposed" (even if they are attached with a twist nut & placed inside a covered junction box).....the power cord itself is the same....an ignition source......

If you take a look at any spray booth (they are easiet to view), even the electrical conduit is sealed at every connection point, every light bulb inside the booth is sealed from the air & the booth is electrically bonded & grounded.

Regarding the exhaust- yeah, the temp should be around 600-1000 degrees....and the carbon that builds up on any surface becomes "highly flammable" (literally like gasoline) over time.

and yes, fresh air intake (metal) is a definite.....just like any commercial building.......

 

Off-road spark arrestors are an option for the end of the pipe. If there's a lot of leaves etc and you live in a dry area that could be a good thing.

 

wow, you put a lot of work into that hut. I can't tell by the pics, how do you connect all the electrical devices to it, when you need to use the generator? Do you have to run cords thru the open doors to the outlets in the pic?

 

Post one says he ran conduit and wire.

 

Don't forget a UPS at your computer etc to condition voltage and protect the equipment.

That's a good idea no matter where your power comes from.