Community Forums

HarryStone · 02-28-2021, 01:28 PM

I'd like to replace my non-powered vent in the kitchen with a maxxair powered vent. The problem is getting 12VDC to the opening. The first picture shows the ceiling, with the location of the AC ducting. Unfortunately, the closest source, a 12V light, is on the wrong side of the duct. The next closest light is circled in yellow, and is 8 feet away. The other issue is seen in the second picture. The vent opening is surrounded by welded aluminum tubing. Is this doable, without doing a bunch of damage to the ceiling or my MH?

theroc · 02-28-2021, 04:20 PM

I'm not an expert but there's two reasons why I'm kind of thinking that it's not a good idea to splice it into a light fixture on the ceiling is that 1) it is working on that switch so all the lights on that circuit would be on when you want to use the fan, and 2) depending on what else is on the circuit, the power the fan is drawing may overload it. Yes it would obviously work but I'm wondering if it is the best way to do it.

My preference, if possible, would be to create a new circuit exclusively for the fan where you may even be able to install a wall switch somewhere on that loop ...or at least splice into a hot source so you can turn on the fan without having other things on that circuit also being activated? Yeah, it would be a pain to do it in this manner but I've heard it being done.

eta: coincidentally, I just ran into this video that basically is saying the same thing.

https://www.youtube.com/watch?v=jlLawC6RjLE

ByeTheWay · 02-28-2021, 04:31 PM

You don't want to overload the existing wire and cause a fire. I have run new wires thru AC return vents from one end of the coach to the other. These were for a backup camera, and a ham radio antenna.

HarryStone · 02-28-2021, 05:20 PM

Quote:

Originally Posted by theroc

I'm not an expert but there's two reasons why I'm kind of thinking that it's not a good idea to splice it into a light fixture on the ceiling is that 1) it is working on that switch so all the lights on that circuit would be on when you want to use the fan, and 2) depending on what else is on the circuit, the power the fan is drawing may overload it. Yes it would obviously work but I'm wondering if it is the best way to do it.

My preference, if possible, would be to create a new circuit exclusively for the fan where you may even be able to install a wall switch somewhere on that loop ...or at least splice into a hot source so you can turn on the fan without having other things on that circuit also being activated? Yeah, it would be a pain to do it in this manner but I've heard it being done.

eta: coincidentally, I just ran into this video that basically is saying the same thing.

https://www.youtube.com/watch?v=jlLawC6RjLE

Thanks for the video.

That's kinda what I thought, but, since my lights are switched at the lights themselves, that wouldn't be the issue. I guess I'll keep looking

HarryStone · 02-28-2021, 05:21 PM

Quote:

Originally Posted by ByeTheWay

You don't want to overload the existing wire and cause a fire. I have run new wires thru AC return vents from one end of the coach to the other. These were for a backup camera, and a ham radio antenna.

I have no AC return vents on my coach. Thanks though.

153stars · 03-01-2021, 12:03 AM

Figure out total watts of lights of that wire run . To be sure pull the fuse note the amps. Divide watts by 12 tack 10% back on for loss if florescent . See what's left over to run a fan. You could convert to led strips/bulbs in lamps if not enough power left. That would probably be easier than new wire run and have benefits of LEDs.

HarryStone · 03-01-2021, 10:11 AM

Quote:

Originally Posted by 153stars

Figure out total watts of lights of that wire run . To be sure pull the fuse note the amps. Divide watts by 12 tack 10% back on for loss if florescent . See what's left over to run a fan. You could convert to led strips/bulbs in lamps if not enough power left. That would probably be easier than new wire run and have benefits of LEDs.

That's a good idea. I've just replaced the bulbs in my MH with the LED replacements. I'll check the load out.

royharm · 03-01-2021, 09:46 PM

I removed a panel in cupboard by my panel read outs, found a 12 volt live circuit. Then I measured and cut out the head liner of my 2004 journey for five pot lites. Using a 5 ft piece of fish tape a electrician would use I pushed it from one of the air conditioning ducts to the 12 volt circuit then to each pot lite. Made all the connection in the air conditioning duct work of ceiling, turned out very well. I think getting a live 12 volt wire to the fan should not be a big deal

Mile Marker 42 · 03-01-2021, 10:13 PM

I'm not sure how concerned I would be about overloading the circuit as those fans today are pretty energy efficient. I'm guessing your lights are mostly all on the same circuit? Have you changed all your bulbs to LED as that would help lessen the draw on that circuit, especially if you can get a wire up and over or under the A/C duct to power your new fan. I would drop the light and see what type of access you have to snake a wire over or under the A/C duct to the vent opening. My openings look like yours with that aluminum. I would drill a 1 inch hole in the aluminum facing the nearest light and get a fish tape or long metal coat hanger and start fishing. I have added wires like this many times, especially when tapping off a 12 volt light to add USB outlets near by. The key is be patient while fishing your fish tape or coat hanger through to where you need it to come out. It took me 30 mins 1 time to fish a wire from my rear A/C to an area in the ceiling 4 feet way.

HarryStone · 03-02-2021, 04:37 PM

I checked the lights that are on the 15 amp fuse, and there is apparently only 3 of them. Not sure at this point if there is other items on the circuit, will have to continue to check, and look at the wiring diagrams. I did purchase a borescope from HF. I found out there is a channel already cut above the AC duct that goes from one side of the coach to the other. I would just have to drill a hole in the aluminum and drill out the foam about 14" to get to the channel. Then fish the wires thru. I think it's gonna work...

Rwjsim2003 · 03-02-2021, 05:33 PM

Did you remove the vent and look to see if there is already a 12volt line there? I did that in our last MH and found the line was already there to power the fan. Some manufactures put it in as some models would have the fan installed at the factory.

chuckftboy · 03-02-2021, 05:47 PM

Harry, if all else fails you might take a look at 3/4" wire molding raceway. It can be surface mounted with 2 sided tape so there is no damage to the ceiling and isn't very noticeable when installed neatly.
Chuck

HarryStone · 03-02-2021, 06:08 PM

Quote:

Originally Posted by Rwjsim2003

Did you remove the vent and look to see if there is already a 12volt line there? I did that in our last MH and found the line was already there to power the fan. Some manufactures put it in as some models would have the fan installed at the factory.

As seen in the picture, the vent opening is surrounded by welded aluminum. No opening for wiring.

HarryStone · 03-02-2021, 06:16 PM

Quote:

Originally Posted by Mile Marker 42

I'm not sure how concerned I would be about overloading the circuit as those fans today are pretty energy efficient. I'm guessing your lights are mostly all on the same circuit? Have you changed all your bulbs to LED as that would help lessen the draw on that circuit, especially if you can get a wire up and over or under the A/C duct to power your new fan. I would drop the light and see what type of access you have to snake a wire over or under the A/C duct to the vent opening. My openings look like yours with that aluminum. I would drill a 1 inch hole in the aluminum facing the nearest light and get a fish tape or long metal coat hanger and start fishing. I have added wires like this many times, especially when tapping off a 12 volt light to add USB outlets near by. The key is be patient while fishing your fish tape or coat hanger through to where you need it to come out. It took me 30 mins 1 time to fish a wire from my rear A/C to an area in the ceiling 4 feet way.

The circuit my lights are on, also run the bathroom fan, and the furnace. Furnace is 4.6 amps, fan is 5, and the lights are 6 watts each. So, that circuit 'could' handle another fan, barely.
I like the idea of using the AC circuit. Each one is fused independently with a 3 amp fuse for the DC, and the 2 AC units are the only thing on the circuit. Problem is the front AC is about 4 feet from the vent opening. Edit; I can't get to the wiring without dropping the inside mounting plate, which also mounts the AC to the RV. Not gonna happen.

The other option I have is moving the bathroom fan to the bathroom light circuit. That has 3 lights and the range hood fan and light on it. Also 15 amp circuit. I think that may be my best option.