Whole house fan control

project_hvac

(Tracy Waalkes) #1

I have a whole house attic fan that is currently controlled by a high/low rocker switch with a 12 hour timer. I would really like to add smart control to it and can’t seem to find one. Any suggestions? Alexa enabled would be a plus but I’ll take any suggestions.


(Bryan) #2

I’d start by examining your high-low switch to see how it works. At least some fans that use a high-low switch use a 3 way switch. The line comes from the timer to the common of the three-way switch. The load is then routed to the fan using either the black or red of a 3-wire. So depending on which is energized, you get either a high or low speed.

If you switch works like that, and your timer is in a separate slot in a duplex box, I think you could remove the timer and switch and replace them with two smart switches, one for low and the other for high. The only problem I see with this is a fail-safe to keep from both the high and low being powered at the same time, as I’m not sure of the ramifications of that.

You didn’t provide a lot of details, so this answer is based on having a separate time and switch in a duplex box.


(Tony) #3

I had a similar setup. The solution for automated on/off with speed selection via an adjacent manual switch is quite straightforward (automated speed selection would be less so and I didn’t see enough advantages to tackling that capability).

What I did was replace the single gang box with a dual, and replaced the old high-low motor switch with this one MasterFlow 2 Speed rocker

Next to this i fitted a GE 14291 In-wall Smart Switch (not a dimmer!); you would use something appropriate to the load requirements of your motor. The GE is rated for 1/2 HP motor 1800W (15A) resistive and works well in my application. Basically you take the AC wires that fed your old timer switch, re-connect them to the line inputs of the smart switch and then run the load wires from the smart switch to line input of the 2 speed rocker, This rocker should wire to the motor the same way as your existing timer switch if it is compatible (note that this arrangement is not for the type of motors used in speed controllable ceiling fans; there are special smart switches meant for those applications).

I like this arrangement because I can use the 'OFF" position of the 2 speed rocker to guarantee that my fan is disconnected from automation (when I am up in the attic working I don’t want anything in the cloud controlling my fan and the rocker is more convenient than tripping the breaker or the tiny air gap of the smart switch).

Of course voice control comes along with the use of the Z-Wave switch; my biggest challenge there was addressing my paranoia about inadvertent voice actuation (I don’t want the whole house fan operating unless a sliding door or window is open, and especially not when my parrot is in the vicinity). I also don’t want Alexa somehow mis-interpreting some random noise as ‘turn on fan’. So I have a couple of apps that will disallow fan ‘on’ commands unless there is sufficient ventilation, and also require two voice commands before sending an ‘on’ command to the smart switch. One voice command turns on a momentary (10 sec) virtual switch to ‘arm’ the second voice command that will actually turn on the motor.

I also use a few of ‘turn off in xx minutes’ apps (initiated by virtual switches turned on by Alexa) which work well as substitutes for the old mechanical timer.


(Jason "The Enabler" as deemed so by @Smart) #4

I had the same situation with my fan. There was a hi/lo switch and the on/off with timer.
What I did was remove the on/off with timer module and replace it with a GE in wall on/off paddle switch. I left the hi/lo in place because I didn’t feel that there was enough need to figure that one out. lol.

I use automation with my fan and it works great. Basically I have rules that when it turns on it checks to make sure there are XX number of windows open. If there aren’t enough windows open it turns off and alerts me about the windows. It also turns off the thermostats when it turns on. When it turns off it announces what windows are open, this way I do not have to check every window in the house. It also turns the thermostats back on and sets them for the appropriate mode.

It would be nice to replace the hi/lo switch with a smart one, but I haven’t found a solution for that yet. I’m thinking maybe a smart relay behind the switch.


Best option for whole house attic fan
#5

Just be careful that whatever switch you use, if your not triggering a relay, is rated for the fan horsepower you are going to control. Not all on-off switches will work well with fans that have a large initial draw. You could start a fire.


(Mr.T) #6

Any recommended automation for the switch? I’d like to say “Alexa, turn on house fan for 4 hours”.


(Tony) #7

I’m still a Rule Machine user (for which I have virtual switches named ‘x minute fan timer’ depending on how long I want the fan to run). The virtual switch when turned on acts as a trigger for a ‘delay by x minute’ off command for the fan X minutes later. You could do the same with WebCoRE, in your case you would name your virtual switch ‘house fan for 4 hours’. Your Echo device (after discovering the virtual switch) would then respond to your voice command as you wish.

Not sure how exactly you would need to name your switch to ensure the command is interpreted correctly ( for for hours or four four hours?); some experimentation may be required. I’ve had issues with controlling my mail box alert in this regard (for at time it was not recognized unless I called it ‘male box alert’).


#8

Our 1954 attic fan switch went directly to a plug in the attic. I often though of putting a smart plug on it. We had to take it out and use the hole for an attic ladder. I hadn’t thought about the power draw. I guess it’s a good thing I never tried it.


(Mr.T) #9

Heh, would not have pegged Alexa as being discriminatory. I suspect your Mailbox is not happy abut that. Good thing our devices have not reached the state of cognition yet. :open_mouth: