Thermostatic Switch and Electric Fan Relay

[Depewtee]

Hi All!

I am in the process of moving my gen set controls from the driver's area back toward the center of the bus.  This made sense as I was always having to leave the driver's area to make sure all, or at least most, electrical circuits were off before starting the generator.  Anyway, while doing this I decided it my be a good time to consider rewiring the electric fan that helps cool the gen set radiator.  Presently,  there is a relay hooked to the electric fan that is triggered by the gen set on switch - when the generator is on, the fan is on.  I know that on passenger cars the electric fans are triggered on when the engine reaches a certain temperature.  Shouldn't my gen set electric fan be set up this way as well?  I checked the operating manual for the gen set and the specified temperature operating range is between 165 and 185 degrees Fahrenheit.  The motor for the gen set is an Isuzu 3-cylinder diesel with a Mecca 15 KW generator.  What are your thoughts?

I am thinking this is what I need.

Brian

[paul102a3]

Brian,

In most passenger cars, the fan is only needed when the car is stopped or is moving in stop and go traffic. Once a car hits moderate highway speeds, the fan is no longer needed so shuts down to save energy.

Unless your generator is mounted so that the radiator has forced outside air, the fan will need to run full time so installing a thermostatic control adds to the complexity of the genset with little or no benefit.

I don't know about your specific genset but many gensets use the radiator fan/compartment blower to help draw air away from the electrical end of the genset. The electrical end of your genset has it's own internal fan to cool the components and the radiator fan helps move the warm air from the area. 

Paul

[Depewtee]

Paul,

Thanks for the reply.  I guess I should have added that my gen set is in the second bay on the driver's side (MC-9) and has two squirrel cage fans that constantly force air from the bay one into bay two.  It also has an air duct in bay two that runs back into bay one and out the bottom of the bus.  My concern is less with the electric fan coming on when the coolant is hot, but remaining off when the coolant is cool.  I can just see me running the generator this winter with the temperature in the twenties and having the cooling fan running.  Does it make a difference?

Brian

[blue_goose]

I have just moved the gen set in our coach and put the radiator in the front of the bus.  I used a Hayden fan control to turn the fans off and on.  I am having some problems that once in a while the gen set will over heat.  I am going to put a light on the dash so I can tell when the fans come on, because I think they fail to come on when I am having the heating problem.  There is a blower in the gen box that runs all the time to keep the sound box cool.  I think it is doing the job, but when we are moving I don't know which is failing. 
Hayden makes 3 types of controls, they are sold at all Auto Zones.  Parked with 3 airs running my fans only run less than half the time in 95 degree weather.  Don't know how much they are running going down the road.  Will know by the end of the week, because the light will go on the dash before the next move in our trip. 
Jack

[paul102a3]

Brian,

I have a similar setup to yours with a single squirrel cage fan that draws air from the drivers side of bay 2 and passes it through the radiator and then out the bottom of the curb side of the bay.

The genset does not have a separate fan for the radiator and relies on the squirrel cage fan to create the air flow needed to cool my 14.5 KW. It has been this way for 21 years and there is no sign of the genset ever overheating.

The only issue I have is I must have the curbside bay door closed when the genset is running or the squirrel cage fan does not pull air through the radiator. I have about 5 minutes of run time with the door open before the water temp starts to climb.

Depending on the ducting and capacity of your squirrel cage fan system, your genset may run just fine without the radiator fan so it may be worth installing the thermostat control.

How do you like the Isuzu engine? Do you have much vibration? The reason I ask is I had a 3 cyl 12KW version in a boat for a short time. It never ran very well and had a lot of vibration. The folks that built the genset tried to fix it several times and even replaced it with a brand new one. After a year, I replaced the unit with an Onan.

I still have the Isuzu powered genset but converted it to a land based unit and have it as an emergency backup power supply for our vacation cottage. It sits about 30 feet away from the cottage in the back corner of the workshop so it can now vibrate all it wants without bothering me. I was just curious if they every solved the problem.

Paul

[gm4106]

I have a 20 KW generator with an Isuzu diesel engine 4LE2 4 cylinders with a Marathon pancake head. I don't think it's the top of the line generator that Hanco offers maybe middle grade.  it's has it's own radiator and fan runs great not heating problems or any kind of vibration at all very happy 

[Depewtee]

Jack -

It was dark last night when I was working on rewiring the gen set.  Coupled with the fact that my unit is not on a slide out, I did not notice that it already had a thermostatic switch mounted to the engine.  This morning I went out and "climbed in" the gen set bay to take a closer look at the back side of the unit and noticed the switch.  I still have some rewiring today on both the gen set and the squirrel cage fans (see links below).  I started the gen set this morning and placed a load on it by turning on the air conditioners.  It ran for about 30 minutes before the electric fan turned on.  There is an auxiliary mounted water temperature gauge located in the third bay for the gen set engine.  It remained at a constant 160 degrees (not a very good gauge, so I am not sure of the exact temperature or accuracy).  I am in the process of redoing my dash, so I will mount a gen set water temp gauge in the new dash.  The electric fan was pulling air through the radiator and out of the mesh door on the bay that used to contain the driver's air unit (I think that is what was in there - small compartment right behind the driver's side tire with a mesh swing open door).

Paul - This is my first bus and first vehicle mounted gen set, so I do not have a baseline for comparison.  However, the vibration does not seem bad at all.  There is a good shudder when I start the motor and stop the motor, but during normal running I do not "feel" the gen set running.  It is not too loud inside, and, although it is louder on the outside, it is really not bad there either.  The engined exhaust vents through the roof so I think that helps.  There really is no sound deadening material in the gen set bay - just a piece of plywood separating the driver and passenger side compartments and one 2' x 2' acoustical ceiling tile propped against the rear wall.  What is every one using to help reduce gen set noise?  In all, I am very pleased with the Isuzu engine; although, remember I do not have a suitable comparison.  I am sure as I start attending bus nut rallys I will learn the advantages and disadvantages of the system I am running. 

My next big project, once funds are available, is redoing the coach battery system/inverter/charger.  Currently I have two deep cycle automotive batteries with a battery charger hooked to them to keep them charged.

Gen Set
Squirrel Cage Fans

Thanks for the replies and information, they are very helpful to a newbie,
Brian