DIY Fantastic Fan

[rwbradley]

I am curious on peoples thoughts on an idea that just came to me. I have a TT with a single ceiling vent in the bathroom, it has a basic switch operated fan with a standard MaxxAir covering it and the switch on the wall to turn it on and off.
I thought this could be an easy and free mod but am not sure if it would work. It occurred to me that the fan operates on DC and I have an old house thermostat (non digital that also operates on DC). I could mount the thermostat on the wall beside the switch and wire it inline after the switch, so that when the temp inside reaches whatever temp I set the thermostat to (say 90) the fan will automatically kick in. If I want to run it manually I can just side the AC temp all the way over to the end and the switch will operate manually.
Any thoughts or potential flaws with this idea???

[DrewE]

Pretty much any automotive relay would work for this.

Be aware of the kind of thermostat you're using. Many household thermostats use a mercury or similar tilt switch that is mounted to a bimetallic strip (like in a dial thermometer). If such a thermostat is not level, the temperature setting will be inaccurate; also, jostling may cause it to bounce on and off. (Many of them are calibrated/adjusted by tilting the internal mechanism, in fact.) Neither of these is much of a problem for a normal house, but in an RV conditions are different.

As for why do this rather than just buying a Fantastic Fan: one reason is that there is a very real difference in cash outlay between fiddling with a thermostat and a fan that you already have and purchasing a Fantastic Fan....

[stuplich]

smkettner wrote:
Do you have an actual Fantastic Fan or the typical basic worthless undersized pathetic noisemaker?

Start with getting an actual Fantastic Fan or other equivalent brand.
Self install is not much more than the thermostat contraption.

Here is a nice fan to upgrade any old roof vent:
http://www.adventurerv.net/hengs-vortex-vent-kit-p-27485.html?gclid=CJrdhYm8h8MCFQkuaQodXR0AGA&utm_campaign=partsfeed_ppc&utm_medium=cpc&utm_source=Froogle
Mel
'96 Safari

[time2roll]

Do you have an actual Fantastic Fan or the typical basic worthless undersized pathetic noisemaker?

Start with getting an actual Fantastic Fan or other equivalent brand.
Self install is not much more than the thermostat contraption.

[opnspaces]

I have a handful of the black 12v relays that come with aftermarket items like air horns, alarm systems and driving lights. They are all rated to at least 30A and can be purchased at your local auto parts store. I would bet that at high speed a fantastic fan pulls 3 to 5 amps maximum.

[rwbradley]

To answer the questions about why bother... same reason you climb a mountain, it is there. It would be an interesting free (or almost free) Saturday project 🙂

A relay makes sense... high school electronics is coming back to me now. I wonder if a Automotive Relay would work, it should be 12DCV? The real question is how much current the fan will draw.

[CA_Traveler]

old guy wrote:
why go through all that trouble when fantastic fans already come that way.

Plus they automatically open and close.

[travisc]

I actually did something similar- I had a basic fantastic fan on the overhead bunk ( class c)and decided I wanted to upgrade it- so I bought the upgraded model to install and then put the "guts" of the basic one in the bathroom- its nice setting one to push and one to pull to move fresh air through the rig.

And I don't have a loud fan in the bathroom

[RRoger]

Easy to do, the secret is you need a relay. When the thermostat come ats close, it completes a circuit that actuates a bigger switch that can handle the current draw of the thing you want to energize.

[rrupert]

old guy wrote:
why go through all that trouble when fantastic fans already come that way.

I agree, just use the built in thermostat. You will just have to adjust it manually until you reach the desired setting.

[crabbin_cabin]

Much simpler to buy the Fantastic Fan model that comes with a remote/thermostat!

[aamyotte]

You should add a relay to make the contact of the fan instead of running the power through the thermostat. This would prevent from frying the thermostat with the fan load.

[old_guy]

why go through all that trouble when fantastic fans already come that way.

[coolmom42]

The thermostat wiring is probably not designed to handle the current load of the fan, wired the way you describe it. I would be very concerned about overheating the small thermostat wires, if you ever got it to work. Plus thermostats are designed to work on AC, not DC, and most are 24 V, not 12 V.

[the_bear_II]

Never tried it but sounds like easy enough to test your theory by temporarily wiring it.

Although it just occurred to me that the home thermostats operate on 24v using a transformer setup. But it's worth a try.