Generator cooling air flow (VERY HOT)

tpi wrote:

Cylinder head temps of these engines should not be approaching anywhere near 450-500 degrees F-

I'm sorry if my "style" offends you.

Depending on the material it is hitting and the circulation pattern, heat can be cumulative. The material a 250 degree stream of air is hitting can reach temps much higher.

It probably wouldn't in this kind of a situation though so your comment is relevant and helpful.

A few comments-the Onan models I have installed recently all had specs for air intake temperature rise over ambient- measure ambient away from genset, measure temp at air inlet, 25 degree max over ambient is maximum allowed.

While I wouldn't worry about the genset starting a fire, it will make any grass underneath much more flammable. There's a good reason the mufflers have spark arrestors in them.

I've seen more than one car burn when parked on dry grass because of the heat from the catalytic converter. I've also seen a Prevost burn because of the Aqua Hot exhaust on dry grass (though I suspect a malfunctioning webasto burner for that one).

tpi wrote:
Cylinder head temps of these engines should not be approaching anywhere near 450-500 degrees F- let alone the discharge air from the cooling ducts. If the engine was running that hot- wait- it wouldn't be running. But one can measure the discharge temp in an effort to be sure.

The only thing I can think of would be some kind of exhaust malfunction where hot exhaust was directed at ground, or exhaust piping was too close to ground. Armed with a thermometer of appropriate range the OP could quickly confirm whether there is a problem here.

Finally .... a voice of reason!

That echoes my thoughts when I first read the OP. Something may be wrong with their generator.

The cooling air from my built-in Onan is in no way is hot enough to start a grass fire - and we do use it in hot weather for A/C when drycamping. The exhaust from it is pointed horizontally to the side well above ground level and is not very hot, either. The steel case of the muffler is what is hot, and it's well up inside the generator's factory enclosure where it belongs.

If push comes to shove, the OP can do as I suggested earlier - throw a piece of thick carpeiting (brought along for that purpose) under the generator where the cooling air exits.

While I'm hesitant to post again on thread by this delightful individual, it is a good topic.

The chart from link shows ignition temps of various materials relevant to the discussion:

http://www.fs.fed.us/t-d/programs/fire/spark/html/74511201/74511201.html

Cylinder head temps of these engines should not be approaching anywhere near 450-500 degrees F- let alone the discharge air from the cooling ducts. If the engine was running that hot- wait- it wouldn't be running. But one can measure the discharge temp in an effort to be sure.

The only thing I can think of would be some kind of exhaust malfunction where hot exhaust was directed at ground, or exhaust piping was too close to ground. Armed with a thermometer of appropriate range the OP could quickly confirm whether there is a problem here.

joe b. wrote:
I think you could get a grass fire going under a bottom venting generator.

WOW. A rational answer.

I think so too.....but it probably would take "underbrush" a bit thicker than 1 inch thin grass to do it.

I have decided to get a small fan; looks like about $15....and it can do other duty sometimes too.

Turtle n Peeps wrote:

Sorry it was not helpful to you. :R Next time I will talk about exhaust. :B

Are people REALLY his dense ?? Sorry, rhetorical question.

Between my initial post and your reply, there were about a dozen other replies. Without you QUOTING which post you were replying TO,
the "yep and nope" was pretty much meaningless.

Understand ??

pitch wrote:
Vulcan, not going to touch your generator question. I am, however amused at your attempt to keep this thread on topic.
You have been a member here for over a year. Did you forget where you were posting? This is RV.net, where there never has been a point made that has not been disputed, never a direct answer given to any question, and the art of misdirection and obfuscation have been honed to perfection!

True. But that doesn't exclude expressing a little mild displeasure with one of those things from time to time.

I think you could get a grass fire going under a bottom venting generator. For a number of years we owned a ranch in south central Oklahoma and had set up a site for our RV, when we were there. One stop, I remember the commercial power, REA, was off so we were running our 4 KW Generac on our Class C. The grass under the generator location was beyond brown after a few hours of running. It had turned black and was charring the grass, with some smoke smell in the area, not from the exhaust. I moved the RV and fired up the crawler tractor and bladed off that area of any grass, then reparked over the same spot where the water and sewer (septic) hoses would reach. The grass in question was really weeds that were a foot or foot and a half high. Was glad to see the REA crew get the power back on later that day.

Vulcan Rider wrote:

K3WE wrote:

Just saying that Jay's post is very valid, even if you perceive that he missed your question.

OK so right answer, wrong question ???

It's not a good idea to jump out of a plane without a parachute either but that's only slightly farther off than the exhaust answer.

I do appreciate the effort in the original answer but your compulsion to defend it is totally useless.

Cool.

Total dismissal of how many replies now?

I think most everyone here has way to much time to think about stuff that someone else already thought about and should just go relax and have a cold drink of their choice if its hot. No reason to try and fix something that isnt broke.