Can I use a 12 volt thermostat to control a fan?

[Big Dave2]

In our wheelhouse we have just one of those ventless heaters and I mounted a truck fan above it to move hot air to the floor. It works great but the problem is I am constantly turning the fan on when the heater kicks in and off when the heater kicks off.

I was wondering if I could somehow use an RV 12 volt thermostat mounted up high to turn the fan on and off automatically? Anyone else do this? What is a good thermostat to use for this? How about a thermoswitch?

[Dave]

We have used a regular round house thermostat and it worked great.

[hydro]

Should work just fine. Be sure to match the electrical capacity (Volts/Amps) of the switch to the load (Fan).

[Lip_Ripper Guy]

I have exactly that setup in my house. It doesn't work nearly as well as I thought it would, but it does work. You'll need a line volt thermostat available at any of your favorite big box retailers. It'll take a little bit of trial and error to get the wiring correct.

The problem that I have with my setup is that the thermostat isn't sensitive enough. So if I would like the fans to turn on at 80 degrees, they may not turn on until 82-83, and then they don't shut off until 77-78 and it seems to take quite awhile to cool those 6-8 degrees. I've played with the settings a little bit and haven't figured it out yet.

IMO a better setup would be some sort of a timer to kick them on for 5 mins every 15 mins, or a voltage regulator to keep the fans running constantly slower.

[Tom7227]

A bit off the mark on this but how does a ventless heater work without giving off carbon monoxide?

As for the fan my guess is that you're better off with a constant running fan that moves a relatively small amount of air. In a house you're trying to pump the warm air all over but in your place you're problem is that the air gets stratified. You need to mix it up to keep comfortable. Maybe just one or two of the trucker style 12 volt fans set on a lower speed would do the job for you.

[Lip_Ripper Guy]

I have no idea how it works, but I have two digital read out CO detectors that have never read above 0 PPM, unless my ice auger is running. I have the small (10k btu) ventless in my 8x12 and it'll cook you right out of there if you want, even on low.

I think you are 100% spot on with having a slow fan turning constantly. If I could turn my computer fans to 1/3-1/2 speed it would be perfect.

[pikechaser]

look for a fan switch that would be used on a fireplace to turn the fan on/off...and mount it on your heater close to the heat exchanger..then run the wires to your fan...most of those switches are going to be rated for 120v...so 12v should be fine..another option would be a fan switch used on a mobile home or an rv furnace...pretty much all newer furnaces you would find in a regular dont use them anymore..thats going to do the best job for you..much better than a thermostat

[Nick Kuhn]

I think you are 100% spot on with having a slow fan turning constantly. If I could turn my computer fans to 1/3-1/2 speed it would be perfect.

Put a potentiometer in series with the fan and you can control the speed.

[BucksnDucks]

[Nick Kuhn]

A potentiometer is a variable resistor designed to limit the power to your output (in this case the fan). With the right one you can control your fans smoothly from 0% to 100% speed. Simple ones work like a volume knob. You can probably find one at radio shack for 5 bucks.

[jonesen]

A potentiometer is a manually adjustable resistor. The way this device works is relatively simple. One terminal of the potentiometer is connected to a power source. Another is hooked up to ground (a point with no voltage or resistance and which serves as a neutral reference point), while the third terminal runs across a strip of resistive material. This resistive strip generally has a low resistance at one end; its resistance gradually increases to a maximum resistance at the other end. The third terminal serves as the connection between the power source and ground, and is usually interfaced to the user by means of a knob or lever. The user can adjust the position of the third terminal along the resistive strip in order to manually increase or decrease resistance. By controlling resistance, a potentiometer can determine how much current flows through a circuit. When used to regulate current, the potentiometer is limited by the maximum resistivity of the strip.

I can't believe you didn't know that. LOL

[sparkydm]

If you want the fan to turn on as the heat rises in your shack, you need a cooling stat, not a heating stat.

[fishing is hot]

Finally someone got it right. sparkydm is right you need one that make on heat rise not fall.

If you want the fan to turn on as the heat rises in your shack, you need a cooling stat, not a heating stat.

[BucksnDucks]

Thanks for the input guys. I'll be the first 2 admit that me and electrical devices dont know much about each other! I have another question now then since this is kinda on the lines of variables. Is it possible to have a dimmer for my 12 volt lights in my house, i had a dimmer switch at first in my house, but had 2 take it out after i first hooked it up and it didnt work. Just seems to bright alot of times and yet would still like some light in the house?

[Lip_Ripper Guy]

To be clear, I have my thermostat set to the "cool" and "auto" positions to work the fans. So if it is set to 70 degrees, and it gets warmer than 70, it will kick the fans on until the temp cools below 70.

I tried a (household) dimmer switch and it didn't work. They have a minimum amp requirement to work, and my computer fans don't pull enough juice.

[Big Dave2]

Thanks for the input guys. I'll be the first 2 admit that me and electrical devices dont know much about each other! I have another question now then since this is kinda on the lines of variables. Is it possible to have a dimmer for my 12 volt lights in my house, i had a dimmer switch at first in my house, but had 2 take it out after i first hooked it up and it didnt work. Just seems to bright alot of times and yet would still like some light in the house?

Wouldn't this potentiometer that everyone is talking about work for this?

[sparkydm]

[quote name='

I tried a (household) dimmer switch and it didn't work. They have a minimum amp requirement to work' date=' and my computer fans don't pull enough juice. [/quote']

Try a dimmer that is marked for "low Voltage"

[Juneau4]

Get an older auto. 12 volt headlight switch. You can wire that to turn the lights on and turn the knob to dimn-just like the dashlights in your car.