Generator fan box sizing

[RoverScout]

Generator phase of the bus project

I purchased a used skid mounted isuzu diesel bolted to a 20kw powerhead
I would like to remote mount the radiator in the next bay facing towards the ground with a squirrel cage fan mounted on top for engine cooling.

How many HP of fan do I need to keep this generator cool in even the hottest of climates ??

I plan on using a cage fan out of a used furnace, I have used these around the shop in the summer for bringing in cool air from outside. Will upgrade the roller bearings and replace the motor with something new.

I will also have a 110 volt exhaust fan mounted in the  generator bay for good air flow around the engine.

Anything else to consider ??

Scott

[chessie4905]

In our 4104, the radiator was mounted vertical and sealed around perimeter so air came in from driver side. The squirrel cage fan was mounted opposite end of bay near generator and blew down towards the ground. Just get an expandable pulley that you can adjust the speed or change pully size as needed. You may need a delay so fan motor doesnt try to start till engine is up to speed.

[richard5933]

I can check the size of the fan/motor Custom Coach used, but not till I get home in two weeks.

But, two things from your plan jump out at me right away. What I'm about to describe pretty much agrees with what chessie4905 has said.

Not sure if the radiator should be mounted flat, especially not facing the road. In addition to it not having the advantage of gravity for flow, you'll be exposing it to every rock and pebble that bounces along under your coach.

Look at the photo of mine that I attached. The air intake on mine comes from the bay on the other side of the bus. The radiator is actually sitting at the inside at the end of the generator head. It's backwards from how they usually are, with the radiator on the end of the engine. You can see the radiator fan intake in the photo of my electric bay.

The radiator sits in the midline of the bus, and draws air from the other side. It flow through the radiator, across the generator head and engine, and then flows out the side. If you look carefully at the first photo, you'll see the wooden partition which was installed between the generator and the squirrel fan/battery area. There is a huge hole in it in the portion which allows air to flow from the generator side to the squirrel fan side. The fan pulls air from across the radiator/generator/engine and then discharges it out through a hole in the floor of the bay directly under the squirrel fan.

This setup brings in fresh clean air from the side of the bus, and discharges the heated air out through the floor. The first thing it contacts is the radiator, not the last, so there is no oil being pulled into it should there be any engine drips.

I have seen other variants of this Custom Coach setup done with the generator mounted across the bay parallel to the side of the bus. The radiator sits perpendicular to the side of the bus in this setup, and a partition is built around the radiator. This leaves the generator and engine on one side of the partition, the radiator in the partition, and the squirrel fan on the other side of it in an air plenum.

There is an air intake in the bay door on the same side of the bus, located at the other end from the squirrel fan. The air is drawn into the intake, runs across the length of the generator & engine, then through the radiator and out through the bay floor under the squirrel fan.

Both of these setups (and all that I've seen Custom Coach do) require a pretty good seal between the edges of the bay and the door, as well as between the edge of the partition and the door. You can't really see it in the photos, but the partition in mine is cut to follow the contour of the inside of the door and has a rubber weatherstripping attached. All this helps keep the airflow how it is intended.

Sorry about being so long-winded, but it's hard to describe all this in few words.

[buswarrior]

How is the generator HEAD going to stay cool?

Lots of busnut rads mounted flat as you describe.

Chime in anyone on road debris experience?

Happy coaching!
Buswarrior

[DoubleEagle]

The one big problem I see is the idea of discharging air towards the ground, and to a lesser degree, sucking intake air from the ground. That works on clean pavement, but when you go on gravel or dirt areas, the dust cloud will be tremendous. The only thing you could do that would be more irritating to others, would be to dump your waste water as you go. On my two entertainers, the intake cooling air is on one side of the bus, and discharge on the other.

Another thing to watch out for on the squirrel cage fans is to note whether it has sealed bearings or an oil cup/felt system that requires periodic oiling. If the fan is buried in the setup, you might forget to lubricate often enough, and the bearings will fail prematurely.

[richard5933]

The one big problem I see is the idea of discharging air towards the ground... the dust cloud will be tremendous...

Our generator creates far less of a problem for us than our engine exhaust does as far as creating a dust cloud. I think the one thing that makes a difference is having an exhaust opening large enough that the airflow is not concentrated in one area with increase volocety. On rare occasions where we're camping or parked on a dusty surface generally there is not a problem after the initial minute or two.

...Another thing to watch out for on the squirrel cage fans is to note whether it has sealed bearings or an oil cup/felt system that requires periodic oiling. If the fan is buried in the setup, you might forget to lubricate often enough, and the bearings will fail prematurely.

When Custom Coach installed the squirrel fans in their conversions, they installed remote grease fittings on the bearings. There are two zerk fittings conveniently located just inside the opening of the generator bay. A pump or two in each when I lube the bus is all that's needed. Once a year I have to put a drop of oil on each of the motor oil cups, which are easy to get to.

[sledhead]

on my genny it came venting the hot air straight down to the ground and I hated it . So I built a diverter vent to send the hot air to the drivers side low under the body .

So now there is no dust cloud   

life is good now

On the M C I  I had a fan speed controller to control the vent fan speed


dave

[luvrbus]

I would use a direct drive squirrel cage blower not a belt driven ,give Dick Wright a call at Wirco International he has BTDT for years

[buswarrior]

There are direct drive furnace fans.

The motor is embedded in one side of the fan.

Scroungers can find either style to suit their install.

Blasting the dirt is just a matter of shutting it off, same as the stock HVàC, if you are running the generator while driving and enter the gravel.

You can be just as complicated or simple as you want to keep the dust down.

I've wondered for some time about a vertical vent shaft, similar idea to a sea chest in a boat, but opposite, everything goes into the vent, exausts, radiator, webasto, and up and away. Coupled with aggressive sound control, of course...

We're always having to fool with this unpleasantness at ground level, add-on pipes and diverters, so why not send it skyward to begin with?

Building your own bus has little to do with "conventional" ...

Happy coaching!
Buswarrior

[RoverScout]

Hey all, thanks for all the great input.
Richard, not long winded at all. Great explanation on how your bus gene is set up.

I was on wrico site, it shows a couple different fan replacement options. Just no idea which one is for which size gene. Will have to make a call.

Generator is going in a front bay on driver's side, might vent in to the void space around the front axle. This would help with the dust issue.

Scott

[DoubleEagle]

Generator is going in a front bay on driver's side, might vent in to the void space around the front axle. This would help with the dust issue.

Scott

That area has negative pressure when you are going down the road. You had best test your placement of things before you make them permanent.

[luvrbus]

   I see a lot of the newer stuff using 12v fans with thermostatic control sensors and it seems to work a friend has a entertainer bus he leases that has 2 pulling and 2 pushing the air on a 22kw Martin generator and tells me it never overheats even in the AZ heat   

[Boomer]

The gen rad on my Eagle was flat and worked really well.  Of course I didn't go off roading with it, that's for school buses.  Big squirrel cage fans and intake air drawn from the void inside my mid entry door steps which was directly across from the generator bay.  I put a simple furnace filter to clean the intake air.  Never had cooling or dust problems.  20KW Powertech.

[Knuckles]

Re: using squirrel cage fans for generator radiator. Why wouldn't you try some of the fantastic 12v electric fans used for automobile radiators they move high cfms and are very slim in design some setups even use two on one radiator. You can get ones that push and some that pull according to your application. I'm sure they would move way more air than a squirrel cage and they are easy to wire in come on and off with temp sensor  I have seen radiators mounted in horizontal positions on drag racing applications so don't think it would be bad on a bus as long as you had a rock screen to protect it

[TomC]

I have a 10kw Powertech with 4 cylinder Kubota. I use a single inlet belt drive squirrel cage blower from Grainger with a 2 spd 1/2hp fan cooled totally enclosed motor. High speed during the day, low speed at night for quieter operation. I only have problems when the temp gets up above 105-I can only run 2 of my roof tops-but usually is not a problem. I recently replaced the blower because the old one's bearings were getting noisy and no one had the replacement bearings (strange). But, this is from our society now that most just R&R instead of rebuild. Works well and is quiet. Good Luck, TomC