Great thanks!!
So I made a rough diagram on how to hook up the Zoo Zen17 relay module.
One concern I have is that I'm planning on putting this in the attic, which the max temp for this says it's 104, and in hot summer days, it will probably get higher than that. Do you think it will be OK or should I try and locate it somewhere else? m
Never even thought of the temp issue in an attic being higher than the relay spec but it certainly exists ! I have two Enerwave relays in my attic right now (whole house fan and attic fan) I just checked their manuals and they also have a 104deg spec. And its over 104 deg now and they work but that does not mean that at some point they will not. My attic fan goes on with a temp switch (sperate from the zwave) at 100deg but the attic will get much hotter than that anyway as it really does not keep up.
Not sure if it is a relay issue or zwave chip issue... Dont want a fire to occur, though. Better to put it in a room or garage. Someplace other than the attic, though that can be difficult sometimes logistically
Thx! I doubt a fire would occur. It probably just wears out the chips in the zwave transponder faster. Typically ICs have a mean time before failure that is spec’d based on temperature. Sometimes (the smarter ones) have built now thermal protection so they cutoff if they get too hot.
I’ll try it in the attic and see how it fares. Thanks again for your help. I should get the fan and the controller in a few weeks. I’ll post it back and let you know how it goes.
Thx!
Do let us know how it goes!
Ah, I might look into getting one. We have an old defunct whole house fan in the attic. Probably hasn't run in decades (before we bought the house). We have since upgraded the HVAC and insulation but AC still has some trouble getting to the 2nd floor due to having no return vent up here. I bet a whole house fan could exhaust the hot air on top very quickly and cool down the whole house in a jiffy. Probably would have to run the AC a fraction of the time.
Good advice here though about negative pressure. We have a wood burning stove and wouldn't want that air coming in. But I'm curious for those who don't have a fireplace or stove: what happens if there are no windows open?
I might hook this up a bit differently...
I would take the hot wire (power input) into the common of relay 1. Then take the NO contact from relay 1 into the common of relay 2. Relay 2 NO contact connected to the fan's high speed input, relay 2 NC contact connected to low speed input. Just wire nuts connecting the neutrals and another for the ground.
This would allow relay 1 to power the fan on or off, and relay 2 would be for speed selection. The advantage is that there is no way for the high and low speed inputs to be energized simultaneously.
Also, most electrical equipment is rated for use at 104 degrees. This works out to 40 C. And is the "standard" for almost everything. Higher than that and you should start derating the wiring, relays, etc. As you noted, you might also see some impact on service life of the electronics.
Brilliant!
Most newer homes (at least around here) have a dedicated vent/duct that keeps the house at a neutral pressure. This vent allows air to enter the home (typically in the room with your furnace or water heater) anytime something in your house is exhausting air. Examples would be a power vented water heater or bathroom exhaust fan. It really isn't meant to draw in 4,000 cfm of air, though, and you would likely have other issues. Air pressure in your home would become negative relative to outside, exhaust fan capacity would be reduced, and you would start pulling in air from anyplace it could get in. Not a big deal if it's a poorly sealed window or door jamb... much bigger problem if it's your water heater flue, gas dryer vent, etc.
I think that's why fans like this are less common now, and "balanced" ventilator units are typically used (required by code?). The balanced units bring in air at the same rate as they exhaust it, preventing any issues like those mentioned above.
Yea, that is one of the things to make sure the windows are open and there is enough airflow. I have a powered fan in my garage and the people who flipped my home drywalled over the vents for it, so it was a huge negative pressure in the garage and it was pulling in air from all over (and it burned out the motors as well). once I cut out the drywall for the vents, improved the circulation considerably.
I automated mine partially. I can turn it on/off but the hi/low is still manual. I'm just using age switch because my fan pulls half the hp rating of the switch.
I wrote an app for this as well. When my weather station detects my predetermined settings are true them it announces that now would be a good time to open the house. All I have to do is start opening windows. When I open enough windows it turns on the fan and turns of the thermostats.
It also tells me when the weather settings are out of parameter. I just close the windows and it resets the thermostats and turns of the fan.
I built in safety measures as well, since I have natural gas in my house. If the fan is turned on and the windows aren't open, it turns off the fan and announces why.
Airscape makes great fans, super quiet, and they (used) to include internet controls. I actually have one with the internet option and I've written local controls for habitat that work great.
Sadly -- they don't seem to offer the internet option any more.... (but the fans are still really great!)
Ah. My home was built in 1930. The ductwork is a maze of confusion since it wasn't added until later. They had a couple "gravity ducts" built with the original house - essentially just a hole in the 2nd floor that goes down to the basement. I guess they might have assisted with the attic fan in some way too, perhaps by drawing cool basement air up directly to the 2nd floor.
@dylan.c, I finally got around to installing the fan and the controller and implemented your wiring and it works like a charm!
Thanks for everyone's advice!
I wish the Zen 17 was around when I installed my fan. My implementation is archaic when compared to this. So much more of a elegant install 
Thanks for all the info here!
Not sure if this is new but I found a new setting for Zen17: DC Motor Mode. It will only allow one relay to be turned on at a time. So now you can go back to the simplified wiring approach if you want. Will be testing this out soon!
any luck? Can you provide the wiring diagram that you're using with DC Motor Mode enabled?
Thanks!
It works! Just wired it up 2 days ago and has been working great. Only problem I named the relays backwards in my HA control screen. My wiring was a bit complicated due to the fact my fan needs ground, neutral, high, low, load. Will get a diagram up shortly. From HA I can safely toggle the two relays, say high is on and I enable low the zen17 box will turn off high first then turn on low.
Which Whole House fan do you have? I have a Quiet cool (high-low speed) with an 8 hour timer. I hate having to actually get out of bed to work the controls early in the morning. Would love to just automate the fan. Then I can work on automatic windows, lol.
unfortunately I'm too new here to post an image. It is pretty straight forward though.
You might look at how to wire up the Quitecool remote: (can't post links either so you'll have to copy/paste and remove the space) quietcoolsystems .com/docs/Wireless-RF-Control-Owners-Guide-2019-6-26.pdf
find your corresponding model number. If your fan only requires 4 wires: high, low, neutral, ground. It is pretty straight forward/easy, run a 3 wire + ground romex up to fan. The only "complicated" part is splitting the "line" (the power) into both the "C" inputs on the zen17. Not sure how comfortable with wiring you are, possibly something an electrician can help you with.
If/when I can post pictures I'll get some up here!
I am curious how other people wired it up and if they tried to do it by code... e.g. did you use a box etc?
Sorry, I have a QuietCool as well, Model# 4195 CFM Energy Saver Advanced Whole House Fan
Download the Hubitat app
