MaxxFan Installation: 12V Power from where?

[R_Lefebvre]

I'm interested in installing a Maxxair Maxxfan system in the front vent of our 1800BH. The exist vent has no fan, so there is no 12V wiring to it.

How do people typically install these and run power?

There are two overhead lights close by, I'm not sure if I can somehow fish these wires over and tap into them? I'm not sure how much power the fans use and if the existing light wiring can handle it? The lights draw less than 1 amp, so could be small gauge wiring.

[backtrack15]

I tapped into the wiring leading to one of the lights (the one to the curbside of the vent). It was easy to pull the wiring from the Maxxfan over to the light (it's pretty open in the "attic"). There was plenty of extra wire attached to the light. You'll find it is a trivial task.

I don't recall the gauge of the wiring (either 16 or 18 I think).

Edit: The lights seem to draw about 0.35 amps each. My measurements indicated the MaxxFan was at about 0.3 amps (speed 3), ~1 amp (speed 6/7), and up to 2.5 amps (full speed). I normally run mine on speed 3.

[R_Lefebvre]

Ah, right, pull the fan wiring to the light hole? Makes sense, should have thought of it. Just wanted to check before I ordered.

[DavidM]

The MaxFan draws about a half an amp on the two low settings, rising to about an amp or so on high. That is small enough for almost any RV DC wire.

But unless the light you are interested in tapping into has a built in switch, you won't get unswitched DC at the light. The light switch will always have to be on to run the fan if you use that connection.

It is tough, maybe near impossible to fish a wire from a wall up to the roof and over to the MaxFan. Try to find an unswitched DC source like at a cigarette lighter outlet or the switch panel for lights, awning, etc. From there you can probably run fish tape up to the roof. Whether there is a barrier or not at the top between the interior of the wall and the roof cavity is where you will have problems. But if you can then maybe you can snag the fish tape from the MaxFan opening before you install it.

It won't be pretty but electrical raceway inside and on the bottom of the roof can get you from a DC source to the MaxFan. Or if you can run the fish tape to the top of a wall, maybe you can drill a hole and pull the fish tape through the roof and run it to the fan on top of the roof.

Like I said, it isn't easy.

David

[Morich]

Consider that even 18 gauge can carry something like 15 amp on really short runs like RV, I would expect the wire size to be okay but it would be worth checking the fuse size before starting as they can undersize those at times.
But for general thinking, I would "normally" expect it to work fine to tap the light fixture.
Over the years, I have done about six and not had a problem with where I tapped.

One point that depends on how your ceiling is insulated may help. Before fully committing to doing the job, I like to verify that I can actually get the wire through from point to point so I find it handy to sharpen the end of a dowel to push through and insulation to the light. If I drill a hole in the end of the dowel, push it through to find there is no metal brace, etc. in the way, I can then tie on the wire and pull it back.
I have had to change plans when finding a ceiling support in the way! But the dowel will let you push through even the solid foam type. I like the wood as it won't gouge any odd wires I might meet.

[R_Lefebvre]

Hi David, yes, good thinking. On my 1800BH there is a light with a switch on it on either side of the existing vent hole, so that wire should be always hot.

Richard, I've already had a look at the roof structure, and believe it's clear through the trusses. The 2021 Micromini definitely uses a wooden truss structure, with 3/8" ply on top, and luan on the bottom. The insulation batting (only about 1" thick it seems) runs along the top, just under the plywood. So should be easy to fish the wire.

[Morich]

The only reason I tend to shy away from the standard fish tape is the way it creates a real headache if I snag something I DON"T want!
When fishing blind, there is always the chance we can snag a small wire that we get the hook set on and can't get free with the really stiff wire, so we wind up with the option of cutting off the fishtape which I don't like and can add more problems to the fishing or we can try pulling hard enough to break it free and that can tear up the wire we snagged.

I like the wood as not going to cause much damage to anything I hit and it works fine for the short open runs in an RV. I got into the sharpened dowel when foam came along as it will push through in a straighter line than wire like 12 gauge might.

My first go at fishing for a light & fan, I got out the long "floppy" drill bit and let it go up through the aluminum roof! I had to hide the damage by putting the CB ground plane in that damaged spot. Yes, it was when CB was the new passing thing!

Be aware that Rv wiring may not always go to the light before the switch but if it is a switched light, one way to deal with the question is to use the wall switch as master and then turn either the fan or the light off with a switch at the item.

[rstraz]

I thought about doing that on our 1800BH, but decided to just replace the bathroom fan with a Maxxair. It does a great job pulling air through the length of the trailer to cool it down.

If you're set on replacing the front vent, have you taken the plastic molding/shroud off? You may be able to see wiring to the click lights without having to fish anything.

[backtrack15]

Since you have a 2021, I’d recommend checking the clearance between the vent and the MC4 solar port on the roof. The Maxxfan Deluxe shroud extends rearward a few inches and sits quite low. I had to build a 1” spacer to clear the MC4 port.

[Marine359]

Originally Posted by backtrack15

Since you have a 2021, I’d recommend checking the clearance between the vent and the MC4 solar port on the roof. The Maxxfan Deluxe shroud extends rearward a few inches and sits quite low. I had to build a 1” spacer to clear the MC4 port.

I have a Maxxair vent Cover over my front vent. Do you think the Maxxair fan model without the built-in vent cover fit inside my existing vent cover?

[backtrack15]

Originally Posted by Marine359

I have a Maxxair vent Cover over my front vent. Do you think the Maxxair fan model without the built-in vent cover fit inside my existing vent cover?

I don’t know if it will fit in the cover, but I doubt it would interfere with the MC4 port (which is great).

[R_Lefebvre]

Originally Posted by backtrack15

Since you have a 2021, I’d recommend checking the clearance between the vent and the MC4 solar port on the roof. The Maxxfan Deluxe shroud extends rearward a few inches and sits quite low. I had to build a 1” spacer to clear the MC4 port.

Yeah, I looked at that and determined it would interfere so I decided to go with the non-delux unit. Will wee how it works stand-alone and maybe not add a cover.

Also considering a Maxxfan Delux for the bathroom fan, just to have at least one that can run while it's raining or moving.

Out of curiosity, how did you make the spacer?

[backtrack15]

Originally Posted by R_Lefebvre

Yeah, I looked at that and determined it would interfere so I decided to go with the non-delux unit. Will wee how it works stand-alone and maybe not add a cover.

Also considering a Maxxfan Delux for the bathroom fan, just to have at least one that can run while it's raining or moving.

Out of curiosity, how did you make the spacer?

I thought about the bathroom, but it looked like the cover would extend beyond the back wall on my trailer.

The spacer is just a 1-inch thick frame made by gluing two layers of 1/2” plywood together. I wrapped it in eternabond. I bought longer stainless screws to replace the ones that came with the fan.

[R_Lefebvre]

Yeah, I measured for the bathroom as best I could and it looks like it would be pretty much line to line with the back wall. Without a precise drawing it's hard to say though, could extend past a little bit.

Wish I had thought of just doing a spacer, but I already ordered the fan.

[Accipiter]

I would pull the inside trim off first because I ran into the something years ago and the company had prewired for a fan. A lot of times they do that to make it easier for the dealer to install a fan. That is what I found when I installed mine, so it is good to check first.

[rstraz]

Originally Posted by backtrack15

I thought about the bathroom, but it looked like the cover would extend beyond the back wall on my trailer.

The spacer is just a 1-inch thick frame made by gluing two layers of 1/2” plywood together. I wrapped it in eternabond. I bought longer stainless screws to replace the ones that came with the fan.

I put a Maxxair deluxe on the bathroom fan. When closed, the cover hangs over by about 1/4".

[backtrack15]

Originally Posted by rstraz

I put a Maxxair deluxe on the bathroom fan. When closed, the cover hangs over by about 1/4".

That’s not bad. What trailer do you have?

[rstraz]

Originally Posted by backtrack15

That’s not bad. What trailer do you have?

1800BH

[R_Lefebvre]

Cool, thanks for confirming.

[SLOweather]

Are you sure the front vent doesn't have prewiring for a fan? I removed my Sunstar's non-fan front vent and there were power and ground wires tucked into a chase in the ceiling foam.