12v power to Maxxfan

Dave&Vivian · 11-14-2016, 07:57 PM

I ordered a Maxxair Maxxfan to replace the bedroom ceiling vent in our 321 RSTS fifth wheel. I pulled the trim piece off the vent to see where I could tap into 12V to power the fan and didn't have much luck. The only 12V I see is at one of the ceiling lights which is connected to a wall switch so that's not going to work.
The trailer did come prewired for a second AC. So I was thinking I could use a 120V AC/ 12V DC adapter I have left over from another project to power the fan. It would mean leaving the adapter buried in the ceiling which I don't think would be an issue.
Has anybody else used this approach to avoid fishing a wire?

**Mustang65** · 11-14-2016, 08:22 PM

I lucked out.. I had a ceiling light about 3' away. Just so you know the temps in the ceiling can reach over 130 degrees in the heat of the sun and I do not know of to many 120VAC transformers that will take that kind of heat. I know that it may be a project, personally I would try fishing the ceiling if at all possible.

OR, you can install a pull chain switch on the ceiling light and leave the 12volt power source on constantly and connect the fan to the light circuit then.

I put a pull chain switch on the fan over the master bed, since the wife could not reach it from a distance

Good luck,
Don

Don

Dave&Vivian · 11-14-2016, 08:43 PM

Good point about the heat in the ceiling, I didn't consider that. The ceiling lights are LED and there are 4 of them on the one switch so the pull chain idea is out.

**Mustang65** · 11-14-2016, 09:36 PM

All the LED's will draw less than a half an amp on the high side, probably closer to 1/4 of an amp. You can take the wall switch out an test the amps if you want.

Don

BuddyRay · 11-14-2016, 10:20 PM

OK, I'm going to suggest something here that I've been considering. And I'm probably going to get "Flamed" by the professional electricians - but here goes.

That 110 wire that goes to your vent area is there as a part of the 2nd AC prep. It is connected to it's own circuit breaker in the breaker panel. In other words, that wire runs all the way back to the panel and isn't connected to or used by anything else.

In that same panel are 12v sources.

Wire is wire (sort of - but any wire large enough to carry 120 at 15a is going to be plenty large enough to carry 12v for a fan).

So my though is, Turn off the power, remove the AC wire from the back of its circuit breaker, connect it to a 12v power and ground source. CLEARLY label it so that some future owner doesn't wonder "what the heck" and hook it back to a 120 source in the future.

Now, at the vent - just hook your fan to this new 12v source. Be sure to label what you've done at the vent end too. It think I'd type a note clearly explaining things and tape a copy of the note to each end of the wire.

If, in the future, you or a new owner wants to actually put a 2nd AC in that vent opening - just reverse the process and put the wire back to 110.

ExChief · 11-15-2016, 04:57 AM

Quote:

Originally Posted by BuddyRay

OK, I'm going to suggest something here that I've been considering. And I'm probably going to get "Flamed" by the professional electricians - but here goes.

That 110 wire that goes to your vent area is there as a part of the 2nd AC prep. It is connected to it's own circuit breaker in the breaker panel. In other words, that wire runs all the way back to the panel and isn't connected to or used by anything else.

In that same panel are 12v sources.

Wire is wire (sort of - but any wire large enough to carry 120 at 15a is going to be plenty large enough to carry 12v for a fan).

So my though is, Turn off the power, remove the AC wire from the back of its circuit breaker, connect it to a 12v power and ground source. CLEARLY label it so that some future owner doesn't wonder "what the heck" and hook it back to a 120 source in the future.

Now, at the vent - just hook your fan to this new 12v source. Be sure to label what you've done at the vent end too. It think I'd type a note clearly explaining things and tape a copy of the note to each end of the wire.

If, in the future, you or a new owner wants to actually put a 2nd AC in that vent opening - just reverse the process and put the wire back to 110.

This is exactly what I did with mine, very easy and not sure why any of the "professionals" would complain about doing it.

**Mustang65** · 11-15-2016, 05:47 AM

Sounds like a GREAT idea to me. Unfortunately, my TT was not prewired as it was supposed to be, hence the ceiling light option. Get/borrow a label gun and as BuddyRay mentioned, tag the wires at both ends.
Good luck,

Don

Dave&Vivian · 11-15-2016, 11:18 AM

Buddy Ray that is an excellent idea. I'm going to pull the cover off the panel box today and do the re-connect to 12VDC.

BuddyRay · 11-15-2016, 10:22 PM

Dave,
I had to pull the cover off and then pull the entire unit out of the cabinet so I could get to both the front and back - but Jayco left plenty of wire so the entire unit pulls out and sits on the floor. Easy if you know electrical.

Cdash · 11-16-2016, 06:33 PM

Two suggestions:

1 - did you reach into the ceiling to see if there was a wire close by? My fifth had a wire right next to the opening, although I'm not sure why. The only thing up front is the switch controlled lights.

2 - I would think that you could pull the trim ring off the bathroom vent and push a fish tape, or stiff wire from bathroom vent to bedroom vent and tire into the power wires that the bathroom vent tires into. Shouldn't be too difficult as they are pretty close to each other.

Good luck!

Dave&Vivian · 11-16-2016, 09:40 PM

Quote:

Originally Posted by BuddyRay

Dave,
I had to pull the cover off and then pull the entire unit out of the cabinet so I could get to both the front and back - but Jayco left plenty of wire so the entire unit pulls out and sits on the floor. Easy if you know electrical.

When I pulled the cover off I saw that it was not going to be something I could do from the front of the panel box. It was simple to remove 3 more screws and then pull the panel box/convertor out of the cabinet. The wires for the circuits are number coded which made using one of the spare circuits easy. Also, in my trailer the 12V ground bus bar is screwed to the floor of the cabinet behind the panel box.
So now I have the vent fan wired to it's own dedicated circuit with a 5 amp fuse. Works great and I feel better that I didn't have to add onto another circuit.
Thanks for all the help and suggestions!

You may also like: