Should fan for generator radiator blow out or suck in?

belfert · March 14, 2021, 11:03:14 AM

Quote from: DoubleEagle on March 14, 2021, 10:49:28 AM
While parked it is possible to put something on the ground, but it might need to be bigger than a mud flap, and wetting might work for a little while. I think the best overall solution is a side wall intake high enough above the ground, and rooftop exhaust. The problem is finding the space inside for that exhaust chimney, but it could be combined with the exhaust piping. Keeping both the exhaust cooling air and the engine exhaust in a long run up to the roof might make it easier to muffle the noise as well. Maybe the waste tank vent pipe could included also. One passage-way for everything you want to get rid of quietly without offending the neighbors.

How would you exit the roof and not have water getting into the bus? The couple of people I have talked to about exhaust through the roof have not really recommended it. My interior is complete so I would have to think long and hard about how to make a roof exhaust work. If the vents are set to pull air in they might very well pull in exhaust with the generator running.

Jim Blackwood · March 14, 2021, 01:05:31 PM

Hmm... so the idea I'm getting from this is that the hot air exit might do well ducted through into the wheelwell with the intake through the door on the driver's side and the exhaust going up the outside of the bus, maybe with one of those double wall stainless rigs they sell at the RV stores, only permanently mounted. That sound about right? Then airbags for feet and an insulated box around the metal enclosure and it should be fairly quiet. At least I hope so.

Jim

6805eagleguy · March 14, 2021, 01:56:28 PM

maybe my bus is special but in between the front tires on my bus is positive pressure going down the road.
I have proof because when we were driving it down the road with a bunch of the inside missing, we had a few holes that you could see the wheels thru, and we had an unbelievable amount of air coming thru there. it was a 90 degree day that day, super hot in the front, as soon as we covered the holes with tape we could feel the air conditioners again.

DoubleEagle · March 14, 2021, 02:03:17 PM

Quote from: belfert on March 14, 2021, 11:03:14 AM
How would you exit the roof and not have water getting into the bus? The couple of people I have talked to about exhaust through the roof have not really recommended it. My interior is complete so I would have to think long and hard about how to make a roof exhaust work. If the vents are set to pull air in they might very well pull in exhaust with the generator running.

The setups I have seen had double pipes running continually from the bottom to the roof top. Any rainwater would drain straight down through. It has the advantage of a natural chimney draft as the hot air rises even if the fan is off. Of course, it would have to be a insulated continuous pipe or carefully sealed sections that are flashed at the roof joint. The flashing could be riveted and caulked just like the roof sections are. Some people have used cement fiber pipe as the outer pipe, but I think that would be more difficult to blend into the metal roof. Screening would keep birds and wasps out.

If you have fresh air vents with fans they would need to be a safe distance away, but usually the fan is blowing out drawing air in the windows, not blowing in from the roof. Space wise, since you have a finished interior, perhaps go through a closet area, or box in a corner.

It's a lot of work, but having the exhaust on the roof increases the chance of the fumes and noise not being offensive to neighbors. It's why people have gone through the effort of installing exhaust pipes on the outside of the coach for generators, either for temporary setup, or permanently. I think the outside pipes are more of a burn hazard, and they don't look particularly attractive. Having exhaust pipes coming out from just under the baggage floor, which is common, is offensive to the people in the campground and in neighboring cars when in stopped traffic. In these days of diesels being targeted as offensive and noisy, I think it is prudent to do what we can to keep a lower profile. Pipe might cost a few hundred or more, the main thing is the time of your labor, because I doubt that anyone is selling a kit to accomplish something like this.

DoubleEagle · March 14, 2021, 02:12:18 PM

Quote from: 6805eagleguy on March 14, 2021, 01:56:28 PM
maybe my bus is special but in between the front tires on my bus is positive pressure going down the road.
I have proof because when we were driving it down the road with a bunch of the inside missing, we had a few holes that you could see the wheels thru, and we had an unbelievable amount of air coming thru there. it was a 90 degree day that day, super hot in the front, as soon as we covered the holes with tape we could feel the air conditioners again.

Yep, your Eagle is special as it is now, but when it is all back together in original layout, there will be high and low pressure areas here and there. My Model 05 had the air intake for the generator compartment cooling located up high in the middle of the first baggage compartment, and it got less air the faster I went. Parked, everything was fine. If I was using it now, I would run ducting from under the front bumper to feed that area at highway speed.

6805eagleguy · March 14, 2021, 02:38:36 PM

Quote from: DoubleEagle on March 14, 2021, 02:12:18 PM
Yep, your Eagle is special as it is now, but when it is all back together in original layout, there will be high and low pressure areas here and there. My Model 05 had the air intake for the generator compartment cooling located up high in the middle of the first baggage compartment, and it got less air the faster I went. Parked, everything was fine. If I was using it now, I would run ducting from under the front bumper to feed that area at highway speed.

Looks mostly normal to me?

It is special tho. Just stating my experience

Yes, I know that's exposed fiberglass on the front...

buswarrior · March 14, 2021, 04:45:41 PM

DoubleEagle, I like the way you think...

I have been fooling with ideas of a thru chamber, ground to sky, that everything offensive dumps into. Generator exhaust and cooling fans, the coolant boiler, tank vents...

Idea sort of germinated out of the "sea chest" concept in larger boats for access to cooling water...

No intrusion or bother to neighbours, or self, when the wind is blowing the "wrong" way. Sound, heat or stink.

Likely some baffling and a dog leg in it to some degree...

An out of coach mock-up to fool with the idea comes in the warmer weather.

I have the luxury of a new build to fool with...

Happy coaching!
Buswarrior

chessie4905 · March 14, 2021, 04:52:56 PM

Just because it goes out the roof doesnt mean it doesnt drop back down to gag somebody. Depends on location when running it.think about wood stoves or coal furnaces.

DoubleEagle · March 14, 2021, 06:18:01 PM

Quote from: 6805eagleguy on March 14, 2021, 02:38:36 PM
Looks mostly normal to me?

Your entrance door sets you apart from all other Eagles, is that the slanted edge window that came from the left front? It looks like you might be missing part of the covers for the spare tire area. That is maybe why you are scooping a lot of air and eliminating low pressure areas in the front. You definitely have done a lot of work, and now you only have a few thousand things left to do.

belfert · March 14, 2021, 06:29:32 PM

Quote from: chessie4905 on March 14, 2021, 04:52:56 PM
Just because it goes out the roof doesnt mean it doesnt drop back down to gag somebody. Depends on location when running it.think about wood stoves or coal furnaces.

It is a lot more likely that the exhaust will go away without bothering people at roof level than at ground level.

That said, there is a sod farm I drive by daily that heats the house/office and other buildings with an outdoor wood boiler. Some days the boiler is just pouring out smoke. Occasionally there will be a day when the wind is calm and the whole area just reeks of smoke.

DoubleEagle · March 14, 2021, 06:36:45 PM

Quote from: buswarrior on March 14, 2021, 04:45:41 PM

DoubleEagle, I like the way you think...

Happy coaching!
Buswarrior

Well thank you, it's because of all the time I spent up in Canada, and watching Red Green.

I think the rough idea of a single chimney for several purposes has potential. I've only been toying with it for twenty years, but now it's time to put up or shut up. I figure my Model 15 will be the one to try it on. The only complication is that it has two generators, and I'd like to get the Series 60 exhaust up on the roof as well. I might gag some people on the ground, but at least everything will be more dispersed and higher up.

RJ · March 14, 2021, 10:59:26 PM

Quote from: belfert on March 13, 2021, 11:54:57 AM
It sucked air in through the radiator which didn't seem to cause any issues. The air was pulled in from the side of the bus and exhausted out the bottom.

Brian -

Below are three photos of the genset configuration in my coach. As you can see in the first photo, there's a screened opening in front of the radiator for cooling air to be drawn in from below. Behind the rad is a squirrel cage blower that sucks thru the radiator, then discharges the hot air out the bottom thru a louvered vent that directs the airflow toward the drive axle. In two years, I've never seen the genset temperature gauge read over 175º, both moving and sitting still.

In the second photo, you can just barely see the squirrel cage blower that pressurizes the genset compartment on the left side of the genset in the rear. This blower draws air in from under the coach thru a similarly screened opening and blows the air over the generator head.

In the third photo, you can see the hot air discharge "chute" in the upper RH corner of the genset compartment. Like the radiator, this chute discharges thru a louvered opening that's also aimed at the rear axle. Both blowers, I might add, start automatically once the genset stabilizes and comes online. There is a small green light on the systems monitor panel that tells me they're operating.

BTW, the radiator is located in the adjacent bay.

FWIW & HTH. . .

belfert · March 15, 2021, 04:44:12 AM

Quote from: RJ on March 14, 2021, 10:59:26 PM
Below are three photos of the genset configuration in my coach. As you can see in the first photo, there's a screened opening in front of the radiator for cooling air to be drawn in from below. Behind the rad is a squirrel cage blower that sucks thru the radiator, then discharges the hot air out the bottom thru a louvered vent that directs the airflow toward the drive axle. In two years, I've never seen the genset temperature gauge read over 175º, both moving and sitting still.

How does the hot discharge air from the radiator not just get pulled right into the air intake?

I see you used the egg crate foam. Doesn't that stuff tend to start to turn into dust with time?

luvrbus · March 15, 2021, 05:28:07 AM

Brian keep in mind your engine is the latest tier model exhaust fumes are not a problem,the older Kubota engines were sorta of nasty burning ,lol a factory hush box generator would have been a lot easier IMO

belfert · March 15, 2021, 07:16:40 AM

In hindsight I should have just purchased the Cummins Quiet Diesel. I can't recall that there were any fit issues. I almost certainly would have gone with an enclosed generator if I could have found one not from Onan or Powertech. I've heard a lot about electronics failures with Cummins QD and that the boards are quite expensive which was a big reason not to choose Cummins QD.

My Kubota is tier 4 final, but I don't know how much the exhaust is really cleaned up. There is no SCR, EGR, or DPF so far as I know. Wrico did say the generator has been derated from 13KW to 12.5KW due to changes with the Kubota engine to meet tier 4 final.