Z-wave Dimmer for Whole house fan ?


Active Member
Anyone recommend a Z-wave dimmer switch to be used on a Whole House Fan ?

The unit is already on a manual triac based dimmer, but I would like some control over the fan.

I saw the vizia 1000va switch for $130.00 but I think that is a bit much.

I have had good results with a Vizia-RF plug in dimmer.
See: My post at AccessHA

I cannot recommend them as I have only had the thing running for about five weeks and do not know how this might shorten the device's life. I am guessing that the wall dimmers will have similar results, I have not actually tried one of those yet.

Does the fan say its designed to work with a speed control, and does the dimmer say its designed to drive a motor of the type your using? If not, its not only against the National Electrical Code, but its also a fire hazard.

Fan motors are designed to use the air flow of the fan for cooling. As a fan is decreased in speed using a dimmer, its air flow also decreases, but the heat it produces decreases at a lesser rate because the fan can become less efficient at moving air at lower speeds when used with dimmers. This causes it to heat up, and it can catch on fire. This isn't a problem for fans designed for speed controls, but a big problem for those not designed for them.

ano has the correct technical answer.

The variable speed ceiling fan in my kitchen has wider/larger air vents than the fans I am experimenting with. It is true that the power dissipated will go down as the speed is decreased. I am not a mechanical engineer so I cannot say what the PD/speed/heat relationship is.

Basically, if you have a cheap fan and run it at too low of a speed the vibration will add enough heat to cause motor failure. I make a point of starting my fan(s) at 100% and then running the dimmer to nothing lower than 40%.

I do have a VARIAC that I once used to control the larger fan (mentioned in my linked post). As time permits, I will collect some temperature data on the fan and the controlling (Vizia-RF) device at various settings.

The bottom line is that what I have suggested is a 'Do It Yourself' solution. Those types of things rarely meet anyone's code. I have spent (in the past) about seventeen years working in 'Research and Development' on military contracts. I sometimes lose the distinction between 'can I do this' and 'can I buy this'. Sorry about that.


There is supposed to be a Vizia-RF Fan Speed control coming out in phase two of the Vizia-RF line, but I do not have any details as of yet.
I thank everyone for the concern, but yes the fan was designed for dimming and the wall dimmer that is currently connected did come with the house fan.

I just wanted to be able to control the speed of the fan based on temperature and open windows/doors. Increasingly I find the fan running with little or nothing open to allow air into the house. And I have come to learn that it will be much easier to just remove the fan and rebuild the house than retrain the inhabitants.

I was hoping that there was a inductive dimming switch available that I just couldn't fine.