2022 GT 27 FB Twin inverter upgrade. Do 2022 trailers have a fridge roof vent?

[foobar]

I am planning out adding a large lithium bank, inverter (victron multiplus II, 2x120v) and additional solar panels to a 2022 GT 27 FB Twin.

As part of that planning, I am trying to figure out how to get rid of the heat generated by the inverter/charger.

My current plan is to install the inverter in the dead space in the back of the wardrobe, next to the 12v only dometic fridge.

I've seen other threads on airforums that indicate that for some time interval after airstream switched to fridges that only run on 12v, the trailers still had a vent on the trailer roof to exhaust heat from the rear coils on the fridge. In those same threads, others have mentioned that airstream eventually eliminated the roof vent for the fridge.

"If" the roof vent exists, I will add path through the upper left hand wall of the wardrobe to allow hot air rising off of the inverter to comingle with the hot air from the fridge and exhaust both sources of hot air through the roof vent.

If the roof vent doesn't exist on recently manufactured Globetrotter 27 FB trailers, then I'll have to come up with an alternative plan.

Can anyone with recent vintage 27 ft airstreams confirm (or deny) that a roof vent exists for the 12v fridge? Even better, provide a photo of the roof that shows where the vent (or lack thereof) is placed?

[daleyocum]

I put my batteries and Multiplus under the curb side twin bed. All the AS low voltage stuff usually comes together in the front of the trailer, often curb side. That makes it easier adding everything. No matter what, you want the distance between the batteries and the inverter as short as possible. Those are very high current connections and the wires are huge.

If it helps, here’s how I did it in my FB25 twin.

Mine only gets warm when running the AC off battery. In that case, I just open the outside storage hatch.

[foobar]

Originally Posted by daleyocum

I put my batteries and Multiplus under the curb side twin bed. All the AS low voltage stuff usually comes together in the front of the trailer, often curb side. That makes it easier adding everything. No matter what, you want the distance between the batteries and the inverter as short as possible. Those are very high current connections and the wires are huge.

If it helps, here’s how I did it in my FB25 twin.

Mine only gets warm when running the AC off battery. In that case, I just open the outside storage hatch.

Thanks daleyocum, that's a nice installation. Appreciate you sharing the photos. Nice job!

Unfortunately, I need manage the rather heavy tongue weight on the Globetrotter 27 FB Twin, so any additional weight for batteries and inverter will need to be over the axles or on the rearward side of the axles (towards the rear trailer bumper).

So I'm stuck with putting the inverter in the closet and the batteries a couple of feet away under the street side settee. That is still pretty close to the inverter as the cables only have to pass behind the fridge to reach the battery bank (couple of feet at most).

[daleyocum]

Originally Posted by foobar

Thanks daleyocum, that's a nice installation. Appreciate you sharing the photos. Nice job!

Unfortunately, I need manage the rather heavy tongue weight on the Globetrotter 27 FB Twin, so any additional weight for batteries and inverter will need to be over the axles or on the rearward side of the axles (towards the rear trailer bumper).

So I'm stuck with putting the inverter in the closet and the batteries a couple of feet away under the street side settee. That is still pretty close to the inverter as the cables only have to pass behind the fridge to reach the battery bank (couple of feet at most).

My tongue weight is about the same as yours I suspect. The FB25s are crazy heavy. Also my tongue weight stayed about the same with the batteries removed from the outside box and moved inside. Lithium weighs about half as much per battery as the AGM batteries they replaced but I have 5 now instead f two. I removed the factory inverter of course which saved a little.

I was concerned about sway if I started putting batteries behind the wheels.

My wardrobe is a set of drawers now which I wouldn’t give up for the world. This is an older picture with my slide out microwave conversion. That’s since been changed so that space is more shelves.

You might give AMSolar a call and see where they would suggest putting the batteries in your unit. I’ve never heard of a professional install like you suggest.

[foobar]

Originally Posted by daleyocum

My tongue weight is about the same as yours I suspect. The FB25s are crazy heavy. Also my tongue weight stayed about the same with the batteries removed from the outside box and moved inside. Lithium weighs about half as much per battery as the AGM batteries they replaced but I have 5 now instead f two. I removed the factory inverter of course which saved a little.



I was concerned about sway if I started putting batteries behind the wheels.



My wardrobe is a set of drawers now which I wouldn’t give up for the world. This is an older picture with my slide out microwave conversion. That’s since been changed so that space is more shelves.



You might give AMSolar a call and see where they would suggest putting the batteries in your unit. I’ve never heard of a professional install like you suggest.

AM Solar was the company who suggested placing the inverter in the back of the wardrobe area and the batteries under the rear bench :-)

[daleyocum]

Originally Posted by foobar

AM Solar was the company who suggested placing the inverter in the back of the wardrobe area and the batteries under the rear bench :-)

Well that will certainly decrease tongue weight! I just hope it doesn’t introduce too much sway. Here’s why it’s a concern.

[foobar]

Originally Posted by daleyocum

Well that will certainly decrease tongue weight! I just hope it doesn’t introduce too much sway. Here’s why it’s a concern.

Appreciate the concern daleyocum. I’m very familiar with sway concepts and the impact of load positioning on trailer stability.

I’ve put together a spreadsheet model for the trailer based on what mechanical engineers would call a free body analysis. Basically, it just calculates the change in tongue weight based on the initial “dry, empty tongue weight” and any loads that are added or are moved around. So I have a pretty accurate idea what the change in tongue weight would be for various potential locations for the battery bank. I’ll keep the tongue weight at around 12-13% of the total trailer weight.

[foobar]

Is anyone able to answer the original question though?

Do 2022 27 ft globetrotters still have roof vents for the refrigerator?

[waninae39]

the fridges with AC and DC only does need a roof vent

only if the fridge gas has it also

as 2022 do not work on gas, only ac or DC

[daleyocum]

Glad you have the weight and balance figured out.

Assuming there isn’t a vent on the roof, there is a large cavity below the wardrobe (that’s where the water pump and a bunch of ducting is.) That would be a great place for a 12v muffin fan, likely thermostatically controlled, to exhaust air if it gets too hot in the closet. Mine seldom gets hot enough for concern in the side storage compartment so I would think that would do the trick.

In fact you might be able to just cut a hole in the right place so the Multiplus’ own fan to exhaust down there. I don’t recall which way they blow.