Electric Fans

[Iver]

I noticed in the latest BC mag. Jack Conrad's article on soundproofing a genset. Good article.  He has installed an electric fan on the radiator. Has anyone else used these fans?  How efficient are they? Do they live up to their ratings?   I see lots for sale online.  The 16" gives a rating of @2500 cfm.  Maybe some brands are better than others?

  Maybe Jack could chime in here?
Thanks, Iver.

[JackConrad]

I used the radiator that was originally installed on the generator (cooled by the fan blade installed on the front of the engine).  I found the largest diameter electric radiator fan that would fit on the OEM radiator.  I have found that the electric fans of the type I used are noisier then the squirrel cage fans.  Because the noise sources (generator/engine, exhaust, and radiator) are separated, the noise level is not a problem for us. YMMV  Jack

PS: Thanks for the compliment about my article

[kyle4501]

If the fan cfm rating does not have the pressure differential listed, it means nothing. That usually means free air movement - BUT, if you are trying to move air thru a radiator, you need to know how much air the fan will move with that restriction in place.
Some fan designs will move huge volumes of free air (no pressure drop), but as soon as you restrict the air a little bit, the volume drops off drastically. Other fan designs may not move as much free air, but don't loose volume capacity as fast. . . .
The fan characteristics are influenced by shrouding, fan blade shape, operating speed, etc.

What you NEED is the fan's performance curve in order to design a properly functioning system.
This fan data is available from all reputable fan manufacturers. It will allow you to know before hand which fans will actually perform better than others.

Moving air isn't like moving liquids. Lots of the rules for moving air seem counter intuitive - If you dead head a liquid pump, the power requirement goes up (because the pressure goes up). But, if you dead head an air fan, the power drops off (because the pressure remains the same & the volume of air moved approaches zero.)

Good luck with this project.

[luvrbus]

The drawback I see with that type fan most are DC voltage and don't give the service or power of the AC voltage type.
I have a 3 speed AC cage type on a remote radiator mount and it has enough power to draw fresh air into the compartment and cool the generator radiator on the low setting.
I did it this way because I don't like vents in the side of my bus.



good luck

[cody]

I have a 12 inch 3 speed fan mounted to the expanded metal on the door of my a/c compartment where my generator is mounted, it blows out and is plugged into an outlet on the generator.  When the generator is running, the fan is running. My concern isn't heat build up on the honda but rather venting the exhaust from it.  I use a honda 3000 inverter generator, it's extremely quiet but the drawback is the muffler is built into it and seems to be part of the housing so to drop it below the floor and out the side or back isn't an option at this point, I'm sure one could be designed and welded in place but so far this method has worked well and my carbon monoxide detector hasn't discovered it.

[rv_safetyman]

When I saw the subject, I thought OH NO here we go again!   When I saw that we were talking about generator radiator fans, I was relieved!

Like others, we have a remote radiator and a large squirrel cage fan.  Works great.  Jack has used a blade fan and it works for him.

Kyle, great post.  I had not thought about the pressure differential issue.  I use 4 electric fans on my charge air cooler and they do not work well.  I am going to a hydraulic fan with a good truck fan blade.  I suspect that it will work great.  Better yet, the hydraulic motor has a two speed capability that I will control with a dash switch.

Jim

[wayne]

These type fans are more than capable of cooling a small generator which is why all the automotive manufacturers have gone to them, even for cooling big horsepower vehicles like corvette, etc. The automotive industry doesn't consider the noise level from these fans as abnormal but in the rv industry this may not be the case. It all depends on your noise level preference, the house type squirrel cage fans are definetly the quietest option.

[luvrbus]

Wayne,that is true but most of us are trying to pull air into a confined space not having the air in front of us like the auto world.
My radiator is between the 2 front bays and the only way for air is to draw air into it and the blade electric fans don't have the power to do  that   
been there done that.



good luck

[wayne]

Clifford

My auxillary rad on my Setra is cooled by electric fans from the factory and I would bet displaces somewhere in the 200k btu range (just a guess).  I don't prefer to use the elec auto type fans but after years of trying to keep engines cool in the limousines we built, we have found that a limo sitting at idle in front of a church on a 95 degree day with a/c running, the only way to keep that car cool are these fans. These cars log in a lot of idle time and we also have failures to deal with because of that. We have never had a overheating issue for a car driving down the road.
I am using the 110v squirrel cage blower on my generator for cooling and sound reasons. I don't have much experience in cooling a small 4cyl  diesel generator so I am following the advice from the company I bought the gen from (wrico), they seem very knowledgeable and helpful. I am always open to new ideas but am trying to go with the proven methods on this project. I just want to get it done and start using it, it's been way too long.

[Busted Knuckle]

Hey Wayne great looking bus! Glad to see ya posting again! I We are anxious to see it in person once you get it on the road!
Keep us posted!
  BK 

[TomC]

My gen radiator is remote mounted. I used a single inlet squirrel cage blower from Graingers.  I mounted the radiator directly to the inlet of the blower and the hot air exits out the side of the bus.  It has a 1/2hp two spd totally enclosed ball bearing fan cooled resiliant mounted motor.  High spd for hot weather and low spd for quiet night time use (you can't here it on low).  Runs well and the only maintenance I've had to do is to retighten the set screw on the blower pulley.  Some don't like belt drive since you can get a womp, womp, womp from the belt, but it isn't that noticeable.  The best part is that even on high, it doesn't create that screaming high pitch that 12 elect fans do.  Good Luck, TomC