Generator Cooling, need more info.

[scanzel]

Getting ready to install my Kohler 10K, it is all self contained with a radiator attached etc. Fuel will be a separate tank. I would like to know how everyone is supplying cool air and exhausting the hot air from the generator compartment. Also how are you exhausting the exhaust and where did you install the muffler ? All comments and info appreciated. Thank you.

[Gary Hatt - Publisher BCM]

You should have a big fan sucking air from the outside, and have a large (12") exhaust hole on the opposite side of the bay.  It is better if it exhausts out of the side rather than onto the ground where it will blow dust all over the place. Externally mounting your generator will aid in cooling.

Also wrapping your exhaust with EHP (http://www.engineheatprotection.com) will force heat out of the compartment to the outside.

[richard5933]

We have a Kohler 12.5 KW genset installed on our bus. The first photo shows the intake - it's on the other side of the bus from the genset. The generator is mounted perpendicular to the bus so that the radiator rides inside on the mid-line of the bus. Air is pulled through that air inlet through a screen in the door and pulled across the radiator.

The second photo shows the generator side of things. The squirrel fan can be seen in the left side of the compartment. There is a hole in that barrier between the generator and the squirrel fan, and the air is drawn in from the radiator, across the genset, and then through the squirrel fan. The air exhausts out through the floor of the bay under the fan. You can't see the radiator in the second photo, but it's at the far end of the generator from the generator bay door.

The airflow first hits the radiator, then the genset, then the engine, and finally is exhausted below the fan. The door to the generator compartment must be closed for this system to function.

Pulling the intake air for the radiator from the side is ideal (rather than from below) since it limits the chance of debris being sucked in from below, especially when parked on grass or leaves.

The exhaust has a 4-5 foot flex line between the manifold and the floor of the generator bay. From there it goes out to the driver's side and exhausts out sideways. The portion inside the generator bay is wrapped in heat insulation to prevent over heating the compartment.

[chessie4905]

Very similar to the setup in our 4104. The only pita was that the main circuit breaker red button was on back side of generator. You had to roll it out to reset. If you forgot to let it get up to speed before kicking in the ac's, it would kick the circuit breaker.
Richard, you should check the heavy wire connections inside the control box annually for burning and tightness. The only change we made was a charging alternator with internal regulator for house and coach battery charging. 2 8-D's, and an electric fuel pump. When we sold the coach, the gen had a little over 2500 hours and was totally reliable.

[richard5933]

Very similar to the setup in our 4104. The only pita was that the main circuit breaker red button was on back side of generator. You had to roll it out to reset. If you forgot to let it get up to speed before kicking in the ac's, it would kick the circuit breaker.
Richard, you should check the heavy wire connections inside the control box annually for burning and tightness. The only change we made was a charging alternator with internal regulator for house and coach battery charging. 2 8-D's, and an electric fuel pump. When we sold the coach, the gen had a little over 2500 hours and was totally reliable.

Our control box is mounted separately from the generator on this installation. You can see it in the photo on a shelf above the 8D battery. It is also on a slide. Much easier than the one on our 4106 where we had to crawl inside the generator bay to access the controls.

I've pulled the control box out this spring and tightened all the connections I could get a screwdriver on. Also replaced a couple of relays which were starting to hang up, as well as the crank reset button which was starting to give me trouble.

Other than the Perkins not liking to start easily in cold weather the unit has been good so far with only minimal work to keep the oil inside the engine. But, the Perkins is a cousin to the Detroit Diesel and likes to make a mess.

[luvrbus]

Get installation manuals from Kolher if has a factory hush box they pull fresh air from the bottom and the generator head pickuos fresh air from the bottom,the radiator fan sucks the fresh air in and pushes it out through the radiator,there is no need for extra fans with the factory hush  box if that is what you have

[buswarrior]

The one peeps forget, dealing with the obvious heat...

Cool air to the generator head.

Having the engine run, and make no power, is a real pain.

Happy coaching!
Buswarrior

[luvrbus]

 A good generator has vents and a fan between the head and the engine to pull air into the head ,my 12.5 had a 4 inch wide slot cut in the floor of the Eagle between the 2 to exhaust the heat, it was nasty when driving on dirt roads too just a cloud of dust coming from underneath the bus but it worked

[Jim Blackwood]

Sounds like given the choice it may be better to draw from underneath than to exhaust there. Seems like an inlet on the entry side would be noisy. Possible to do the entry and exhaust both on the street side? Since heat rises place the exhaust high? Worth pondering.

Jim

[richard5933]

Sounds like given the choice it may be better to draw from underneath than to exhaust there. Seems like an inlet on the entry side would be noisy. Possible to do the entry and exhaust both on the street side? Since heat rises place the exhaust high? Worth pondering.

Jim

How is pulling all that crud off the ground and into your radiator better?

Mine exhausts on the ground. Every single time we use the generator you can see a cloud of debris which it blows away when the generator first turns on. If we're on the grass or in a leaf covered campsite, the cloud of debris being blown away would have been enough to clog a radiator in a few minutes.

If that were sucking up instead of blowing down, I can only image that much (if not nearly all) of the debris would be in/on the radiator reducing cooling considerably.

Noise? Our fan is buried inside the bay. The intake on the street side goes halfway across the bus before the air encounters the radiator. On ours the air cannot be heard over the noise from the Perkins. Perhaps with a quiet engine it could be, but I suspect that the squirrel fan setup is much quieter than a traditional electric radiator fan which is used on many installs.

If you are going to put the radiator on the outside edge of the bay and just slap an electric fan on it, I'm sure that there would be lots of noise from it. That's why Custom Coach re-mounted the radiator and installed it in the inside of the bus and not against an opening in the storage bay door.

[chessie4905]

That slide looks identical to ours. Our radiator in the 4104 was installed in the back( inner) bulkhead in condenser bay, leaving room for extra oil containers, blocks etc. In front of it without blocking airflow. This was designed in early 80's, so things are done different now. The only noise inside the coach was a very slight vibration and hum from gen when it ran. Sort of like sitting inside a cat that is purring lightly.lol. we had a heavy selector switch on left side above driver on panel with 3 positions. Gen-Off-Shore. Once gen was up to speed, you switched to gen. We had one of those Sureshot ether injectors plumbed into air cleaner for cold starting when necessary. The squirrel cage fan was very reliable, and we kept a spare belt for it. It blew the heat from gen compartment onto the ground also. Instead of factory radiator, it had an automotive cross flow model that was about 1 1/2  more surface area than original. Never had any heating issues even in the hottest weather. Setup allowed good airflow through compartment and gen. head.

[buswarrior]

Silent install requires proven techniques of isolation.

Air flow has to turn some corners if you truly don't want to bother your neighbours.
Lots of reading online.

Takes a little space, and some materials to line it if you are going hardcore, but what price do you put on silence?

You can also deploy extra parts at the campground to manage air and noise. Deflectors, panels, etc.

As the push back against the undesirable gypsies roaming in their "tiny homes" gains more momentum...
a generator which is silent outside the coach will help the responsible busnut continue to hide in plain sight.

Happy coaching!
Buswarrior

[Gary Hatt - Publisher BCM]

Sounds like given the choice it may be better to draw from underneath than to exhaust there. Seems like an inlet on the entry side would be noisy. Possible to do the entry and exhaust both on the street side? Since heat rises place the exhaust high? Worth pondering.

Jim

The ultimate setup is to suck fresh air from the side and exhaust out the roof.  Exhausting out the roof is what most of the high-end buses do and you and your neighbors will appreciate it.  Also, the genny should not be mounted behind the rear tires (or front tires for that matter) as that will kick up dust to be sucked into the genny.  The ultimate is to pur your genny in the front of the bus before the front wheels. This is very common and is my preference as it will make your genny last longer.  Dust is not your generators friend. It is also recommended to not run it in fields and dusty places.  Burning  Man is the worst place to run a genny or ANY engine. That is the primary reason that if you rent an RV to take to Burning Man, you will have a pretty hefty cleaning fee. 

[Jim Blackwood]

OK. Well I was just thinking it'd be best not to stir up a bunch of dust and leaves by blowing the discharge air straight at them. Takes a lot more suction to lift stuff off the ground than it does to blow them. Try it with your leaf blower/vacuum sometime. And while a sideways warm air discharge might be a little objectionable it's not as bad as dust and leaves blown up all around.

But Ideally you'd do neither. And the larger the port, the slower the airflow so bigger is better. If you did have to go downwards a large area perforated with moderate sized holes, say 1-2" dia. would be better than a single opening, as well as helping preserve the integrity of the floor. A layer of hardware cloth could be used to keep the leaves out. A panel approaching 3 ft square would reduce the suction enough to not pick dust up off the ground unless it was mighty fine dust, I would think. Even then I suspect enlarging the inlet area more would take care of it.

Still, better to bring it in streetside, of course then you get road splash, so no perfect remedy.

I can see discharging the engine exhaust to the roof, but to do the cooling discharge that way seems overly enthusiastic. It would take a large duct right up through the living quarters and I'll admit I've not seen all that many conversions but I've never seen that done. I'm not sure I'd want it. Seems like putting out the welcome mat for water leakage. I may rethink that idea as the time approaches though, the chimney effect would only help.

In my case, I have an enclosed unit which uses an air cooled engine. It runs on propane so no really nasty stuff in the exhaust. And it's 8Kw so not a massive amount of cooling required. The entire cabinet fits inside the bay easily enough, in fact it's being stored there now. I'm pretty sure airflow goes from the base, through the unit and is discharged at the top. In this case the simplest scheme would probably be a perforated floor and a high side exhaust with the engine exhaust piped out the center of it. But the stack idea has some merit, I'll have to consider that.  The second option is a streetside inlet, but I doubt I'll decide before I've run up the unit and have some idea of the airflow requirements.

For a cooling stack, just at a guess I'd think you'd need a 1 ft square discharge area at the bare minimum. Then what would you do for a stack cap?

Jim

[richard5933]

In the end, a lot of the decisions on mounting a generator are going to depend on the unit being installed. Some of the self-contained units have both the intake and exhaust for cooling on the bottom, so of course on those the easiest route is bottom for both. On others where things are being built from components and there are more choices as things are assembled, it's possible to situate openings for air so they fit the bay better and have better flow.

In my experience, I've found that reinventing the wheel is not always necessary or the best way to go. As long as the wheel is still rolling along, I'm going to stick with it. Over the years many of the larger generators were mounted with side intake and bottom exhaust, using a squirrel fan to move the air. Seems to work well for our setup and for many others I've seen.

Jim - these squirrel fans that are used in installations like mine move A LOT of air, and they move it along at a pretty good clip. If the airflow were reversed and pulling from the floor it wouldn't take much to suck a bunch of dust and crud from the ground. Remember, there are only about 6 inches to the ground on a good day, less if there is grass underneath. You are correct though - I've got to be careful where I park when there are neighbors involved so I don't send a cloud of leaves and/or dust their way. Hasn't really been a problem though, at least not yet.

The most slick system I've seen yet is what we had on our 4106. That Perkins had its cooling system tied into the bus's radiator. Coolant circulated by way of a Bosch coolant pump which ran whenever the Perkins did, and there was an electric fan piggybacked on the outside of the radiator which kicked on as needed through a thermo-switch at the Perkins' water outlet. Never had a problem with either the bus or the Perkins getting too hot, and with the combined system the Perkins was able to make use of the Webasto to preheat and make winter starting easy. Once the Perkins was running, it would help preheat the bus engine as well. I'm sure there are problems with a setup like this as well, but for us it worked.