Liberty Inverter Compartment Fan

[truk4u]

While getting ready to change circuit boards in my Inverters, I found a cooling fan that I didn't even know existed. It's hidden behind a panel and helps cool the Inverters. I checked mine to be sure it's in working order by heating the sensor with a hair dryer. With summer coming (already here in GA, 97) you may want to check yours. Kudo's to Liberty for the fan, that bay gets HOT!:cool:


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[jack14r]

I had a problem with heat in my coach in the inverter bay last summer,it got to 145 degrees so Liberty installed another boxer fan in the bay.Last weekend my thermometer in the bay hit 115 with the outside temperature around 85.At 145 degrees the Allen Bradley system shut down and basically shut down the coach's electrical system,it took me about 5-10 minutes to figure out what was wrong and all I had to do was reset the AB system and open the bay door for cooler air.I now always monitor that bay with a remote digital thermometer and it appears that the extra fan has helped.

[garyde]

I have replaced my Dayton fan once, it runs 24/7. No T-stat.

[Petervs]

Tom, I am pretty sure Brian replaced that fan a few years back, the previous one had quit working.

This brings up an interesting thought process about seasonal performance variations of our coaches.

In summer, we have these kind of overheating situations, keeping the AC working, etc.

In Winter we have leaks in air bag systems because as the rubber o rings get cold they can tend to leak. Rarely does anyone have the leans in hot weather.

Fogged up double pane windows, clogged AC evaporator drains, etc are also seasonal it seems.

[Joe Cannarozzi]

YIKES Jack forget about what the heat is doing to the inverters that is almost dangerous.

Are you reading this all you fellows who run a couple of a/c's off the inverters.

How hard would it be to duct some a/c in to that compartment? Mr czar of cruisair.

What are they 4024's

[jack14r]

I have 2 Outback 3500 watt inverters and Joe you are right about how the heat can hurt the components that is why I have a thermometer in the bay.

[Jon Wehrenberg]

Our coach is set up differently and I'm not sure if that is good or bad.

Our inverters are under the head of our bed, buried out of sight and not easily accessible.

The good news is we have no heat generated in our electrical bay so the circuit breakers and the AB components are not exposed to other than ambient temperatures. The bad news is my inverters are not in there, out in the open so they can be easily serviced.

Since they are heat generators they have internal fans, and when Liberty installed mine they ducted fresh air from the coach interior to the inverters and exhausted the air in the rear outside over the Webasto. To aid in air flow a pair of exhaust fans is located in the ceiling over the Webasto to pull more fresh air through the inverters.

At home the inverters are essentially chargers since we are connected to shore power, so I leave the outside exhaust fans off and rely on the internal fans for cooling. I periodically load the inverters and listen for the internal fan(s) to verify they are functioning. I carry a spare inverter fan because cooling is so critical. When we leave for a trip and will be working the inverters much more than when the bus is stored we turn on the external exhaust fans and they remain on the entire time. When they are working I rarely hear the internal fans kick on because of the fact the external fans are continuously pulling air through the inverters.

No matter how or where my inverters are placed I would always want to have air flow through them. I think heat is damaging to all electronics and while I dislike where mine are located, I think the installation has proven to work well.

[truk4u]

Jack,

That's a great idea and now on my list of must do's..

[Petervs]

Tom, you don't have to ride around in the bay to watch the thermometer all the tlme!

Radio Shack sells a nifty wireless thermometer with a remote. Runs on batteries for a year or two between changes. Only about $20.

[BrianE]

Tom, As Peter mentioned, I did replace the fan. I also added the sensor. Liberty had it wired to run continuously and it was originally wired with no circuit protection. :mad: It had been my intention to add a second fan in the front of the bay where the exit vents are located.

[GDeen]

Wonder how the Marathons are setup for inverter cooling? I will look into it this weekend.

[Ray Davis]

Gordon, let me know what you find. I haven't looked into this on my coach, yet.

[GDeen]

Will do Ray.

[truk4u]

Peter - That's the direction I was going, just a simple remote. Radio shack has one for 9.99, but out of stock, so I'll splurge.;)

Brian - I thought maybe your signature was on the this fan deal, since it was done so well and Jon says his runs continuously when turned on. I'm confused on your reference to the exit vents in the front of the bay. It has two small screen type openings in the rear of the bay that I assumed was the intake when the fan is on. Those small openings would allow fresh air from the gen radiator bay through the screen in the floor. The fan vents inward toward the center of the bus. Where does that vented air actually go?

[Jon Wehrenberg]

Just so I am not confusing anyone I run the auxiliary inverter fan full time when we are in the bus so ambient air is always passing through the inverters, not just when the inverter internal fan kicks on. That way if there is an inverter fan failure it will not cook the inverter, I cannot see or access my inverters without at leat an hour's worth of work disassembling the bed. The inverter installation space is very small and temperatures would ramp up quickly.

If the inverters were in the electrical compartment I would likely do the same thing just to protect the AB equipment. I don't see any downside to providing ample ventilation, and when trying to sleep listening to a fan cycling on and off would drive me nuts. I would keep it simple and use a thermostatic control set at some low temperature like 70 degrees so the total environment is cool. Remote control? Nope. If you want it protected either use a DC fan and an in-line fuse, or use the 120 Volt outlet in the bay.

[Petervs]

Jon, the remote control mentioned was for the temperature readout, it was not really a control, just a sensor.....

My Marathon ( 1994 XLV) has the inverters in the large pass through bay. There is no external cooling fan, nor ventilation to the outside The inverter fans do run and just recirculate hot air, unless I open the bay door.

It has worked fine like this for 15 years, but I do think a source of outside air would be an improvement worth making. I admit we avoid hot places in general.

[Jon Wehrenberg]

That makes sense. The Liberty electrical compartment is fairly small because it is about half the width of the bay because the generator radiator is in he other half. It is also shallow because behind it are two Cruise Airs and in my bus an aux. fuel tank. Unlike a full bay, the guys that have the inverters in that compartment will find it gets very hot pretty quick.

We too avoid temperature extremes, both hot and cold.

[Kevin Erion]

Marathon has 2 fans mounted to the floor of the invertor bay, 1 draws air in and the other exhausts. They are both controlled by a heat sensor, works good.

[GDeen]

Ray,

My owners manual says the inverters have "2 stack vents with fans at the top of each and a air scoop at the bottom of each below the coach."

I found one scoop at the rear of bay two directly below the Inverter disconnects. The scoop is facing towards the rear. Can't see the other one but I did not crawl up under there as I haven't hauled jackstands out to the barn yet.

Kevin, does that sound typical of the Marathons you have had?

[Kevin Erion]

Gordon,
Yes, you should see 2 dryer looking vents under bay 3 on the drivers side, both face the rear. Front one is the intake air with the rear the exhaust. My 99 was the same as the 01. These vents are easy to get bent if you high center so keep an eye on them, I would think you want maximum air flow in and out. The fans inside sit on top of a short tube, not sure why, mabe to cut down on dirt inside the invertor area. I recommend disassemble of the box and a good cleaning, can't hurt and you can see how things look. Like Tom mentioned, take a hair dryer to the heat sensors to make sure both fans are working.

[GDeen]

Gordon,
Yes, you should see 2 dryer looking vents under bay 3 on the drivers side, both face the rear. Front one is the intake air with the rear the exhaust. My 99 was the same as the 01. These vents are easy to get bent if you high center so keep an eye on them, I would think you want maximum air flow in and out. The fans inside sit on top of a short tube, not sure why, mabe to cut down on dirt inside the invertor area. I recommend disassemble of the box and a good cleaning, can't hurt and you can see how things look. Like Tom mentioned, take a hair dryer to the heat sensors to make sure both fans are working.

Great idea Kevin - will add that to the list.

Below is a pic of the vent scoop under the coach at the rear of bay number 2. Still not seeing the other - wonder if it was knocked off? Will get some support under the bus and get under and look more closely.

[truk4u]

I have added a thermostat to my Inverter Bay Fan that allows settings from 80 - 130 degree's. Thought this was a better alternative to having the fan run continuously.

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