Adding roof vent with fan?

120vac // 12vdc power supplies to power something like a fan are cheap and reliable. But they need a tiny bit of ventilation themselves when powering a load.

Thanks everyone!

mtnbbud wrote:
Makes sense. I could trace the wiring back to the fuse box and repurpose it for 12Vdc. I did look at the wiring and it's way thicker gage than I'd need. Is it possible for the wiring to be too thick for my purpose?

No such thing as "too big" of wire gauge :B

Most likely 14ga Romex, at the most 12ga Romex, typically A/C would be own its own 15A breaker.

It will be fine..

Always include a fuse on additional circuits to protect the wiring from overloading due to shorts in the wiring. You can select a fuse size for the lightest ga wire that might be connected (in this case would be the fan wiring). Can get ATC plastic auto fuses down to 5A if you like depending on how much the fan draws..

Makes sense. I could trace the wiring back to the fuse box and repurpose it for 12Vdc. I did look at the wiring and it's way thicker gage than I'd need. Is it possible for the wiring to be too thick for my purpose?

mtnbbud wrote:

Roger10378 wrote:
First you need to find out what electricity is under the wall plate. If it is indeed for air conditioner it is probably 120 Vac. Most power vents run on 12 Vdc so it will be necessary to get 12 Vdc from somewhere. As far as ease of getting the power the rest of the way it is hard to give any advise. All but the cheapest vents have the ability to run either direction. It has been a long time since I have seen one with an aluminum cover so good luck on that one.

Thanks - I didn't consider the wiring being 120 Vac. That makes complete sense and certainly makes putting in a fan tougher. I was hoping it'd be an easy-peasy upgrade. I'm not really in the mood to find and run 12Vdc wiring unless I can keep it in the ceiling out of sight. There is a light fixture nearby, I might be able to use that...

That would be a "prewire" for the at the time optional A/C unit.

Basically the RV manufacturer would have preinstalled the 120V wiring while building the RV in case of the new owner wanting the dealer to install A/C.

Wiring for A/C units are typically done as a "dedicated" run from power panel to A/C with nothing else on that circuit. You might be able to repurpose that wire.

Just need to verify that the wire in that connection box is not hot or connected to a 120V breaker.

That wiring may or may not be installed in your power panel, if no breaker exists for A/C chances are the wiring is just tied up behind the power panel. In this case, you could potentially reuse the existing Romex wire for 12V, just make sure you mark it well for your new use..

mtnbbud wrote:


Also does anyone have any recommendations on a good roof vent fan? If I get one I want the fan has a switch that allows it to run in both directions. I also want the cover to hold up to UV damage (an aluminum cover would be preferable to a plastic cover).

Thanks all for your advice!

see ongoing thread maxaire vs fantastic fan
bumpy

I cut a 14" x 14" hole and added roof vent with fan where none existed before. Ran power from a nearby light. The brand I used was Sureflo, which I don't think are made anymore. It was similar to the Fantastic fans of the same era. The job was easy peasy. It fit perfectly between 16" on center rafters. The kit I used took into account the possible various depths that might be involved and looks OEM.

Roger10378 wrote:
First you need to find out what electricity is under the wall plate. If it is indeed for air conditioner it is probably 120 Vac. Most power vents run on 12 Vdc so it will be necessary to get 12 Vdc from somewhere. As far as ease of getting the power the rest of the way it is hard to give any advise. All but the cheapest vents have the ability to run either direction. It has been a long time since I have seen one with an aluminum cover so good luck on that one.

Thanks - I didn't consider the wiring being 120 Vac. That makes complete sense and certainly makes putting in a fan tougher. I was hoping it'd be an easy-peasy upgrade. I'm not really in the mood to find and run 12Vdc wiring unless I can keep it in the ceiling out of sight. There is a light fixture nearby, I might be able to use that...

First you need to find out what electricity is under the wall plate. If it is indeed for air conditioner it is probably 120 Vac. Most power vents run on 12 Vdc so it will be necessary to get 12 Vdc from somewhere. As far as ease of getting the power the rest of the way it is hard to give any advise. All but the cheapest vents have the ability to run either direction. It has been a long time since I have seen one with an aluminum cover so good luck on that one.