Bathroom fan + humidity sensor?

Title says it. Anyone automated their bathroom vent fan? Worth it? Reliable? Share your… um… bathroom vent project story.

My bathroom fan is on a Z-Wave switch and I use one of these to check humidity and motion.

Currently I have a simple piston that simply checks when the humidity drops 1 or 2 percent, waits 3-5 minutes, and then shut off the fan. I also use the motion sensor to keep the fan running even if the humidity drops if it senses motion. For better reliability, I also have a back-up Power Allowance rule to shut off after 20 minutes. It works for the most part although I have had the fan shut off mid-shower a couple of times.

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Worth it?


I have all of my bathroom fans automated, 4 altogether.

This one is for turning on the fan when someone is in the shower or humidity is just too high or the bathroom/toilet fan stays on too long.


This one is for when someone is doing #2…Switch 33 is Fan in this example

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Nice! And here I thought I was being a bit overboard on automation plans (I have yet to get my lights working right!!), and you not only have four bathroom fans, but automated all of them!

Thanks for the detail on the automation!

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I stopped counting at 200 devices. I will admit that hanging around on these forums, you will find irresistible deals that will compel you to buy “things” that are really not “needs”…:rofl:

I think you are wrong!.. Yeah… You are wrong… My wife is wrong as well…

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Doing it with an app I found on here, not in WebCore.

Just to add to this idea, sooner or later (read: later, much later) I’ll try to do the same thing with a fireplace chimney flue + temp sensor. Obviously, I may need to figure out the placement for the temp sensor. I’m assuming they stop working when burned.

How would you automate opening/closing the damper?

Hmmmm… Honestly, never owned a fireplace before, but yea… I guess there’d be no point to just the fan. And even if I rigger a motor system, that would need to be essentially inside the firebox.

Dammit! Now I’m going to have one old school light switch without any valid reason to replace!

Ah so your chimney has a fan?

I was picturing a standard flue with damper that’s opened/closed by hand.

I mean, I haven’t looked inside. I’d assume it has a damper, but dunno. I’ll check tomorrow. Maybe I should know how my house works, before automating it :slight_smile:

It does have a fan.

My fireplace has 2 switches. 1 to turn on the fireplace and 1 to turn on the fireplace fan.

I discovered that the fireplace switch works with super low micro voltage and there is no 120v source. It actually get its power from the pilot light. The switch opens and closes the gas valve.

The fan works by a thermal coupler that opens when it gets hot enough, which allows the fan to turn on. This is controlled by a switch that sends 120v to an outlet inside of the fireplace that the fan is plugged into.

Knowing this information, this is how I automated my fireplace:

I used a 24v (ac) dry contact relay that receives power from the outlet inside of the fireplace that receives its power from the switch. I used a 120v to 24v step down converter for the dry contact relay.

I then replaced the dumb fan switch with a smart switch. Now when I turn on the fan, the dry contact closes and turns on the fireplace. The fan doesn’t come on until the thermal coupler reaches a certain temperature.

The dumb switch for the fireplace still works and the dry contact is ran in parallel with the dumb switch.

If someone turns on the fireplace with the dumb switch, all bets are off for smarts…outside of controlling the fan. I could have just eliminated the dumb switch but still wanted to be able to use the fireplace in case of power failure.

I have multiple redundant rules that will not allow the fireplace to be turned on programmatically or run too long or over a certain temperature.


That’s really awesome!

But just to clarify, mine is wood-burning.

How does it light? What is the fan hooked up to?

I did pretty much the exact same thing, but you can also add one more piece, if you use a z wave plug in dimmer module and plug your fan into that it will allow you to remotely change the fan speed. The fan speed on those fireplace fans is basically just a rheostat.

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Well how about that! Fan speed (noise) doesn’t seem to be an issue. However, I wonder if I just put a Smart Dimmer where I have the Smart Switch would it work the same. I wonder if the Dimmer on it’s lowest speed, will still send enough juice to the relay to trip it…