One of the main reasons I wanted home automation, was to increase the comfort level in my home. Sure, not flipping light switches has its own convenience, but achieving the ultimate comfort lies elsewhere; precisely, in automatic climate control.
With five people living under the same roof, ever since we built our house six years ago, none of us have been happy with the temperature throughout our home. Hot spots, cold spots and the never ending “tug of war” game of who gets first to change the thermostat’s settings had become increasingly irritating.
My wife likes it cooler, especially at night because we sleep with blankets, but our master bedroom usually runs up to 5 degrees warmer than the temperature set by the upstairs thermostat, so she often turns down the heat. My teenager, on the other hand, whose room is above the garage and runs up to 5 degrees cooler, oftentimes cranks up the heat. My two babies are just…well “collateral damage” in this game. Their bedrooms are more balanced but because they don’t sleep with blankets, 68 degrees is too cold and 80 degrees is way too hot.
This is how the overnight temperatures looked like before I began exploring ways to normalize the room temperatures*.
<img src="//cdck-file-uploads-global.s3.dualstack.us-west-2.amazonaws.com/smartthings/original/3X/e/e/ee908dcb2b09639136f13d2f3c269ecead372b06.jpg" width=“216” height=“400”
So clearly, we’ve had a severe climate control problem. My first thought was to add two new zones to our existing zoning panel. The price estimated for that project came up to roughly $3,000. Doable but I still needed to feed five people and my HA addiction 
So for obvious reasons, that didn’t work for me.
Then I read about “Smart Vents”. They seemed like a great idea to me, but far too many people argue that is actually a terrible idea for the HVAC system:
It’s a really bad idea to close off vents to a room. As energy expert Allison Bailes III notes on his website, most home heating systems are not designed for this. "… the system is designed for the blower to push against some maximum pressure difference. … If the filter gets too dirty or the supply ducts are too restrictive, the blower pushes against a higher pressure.” So when you close vents in rooms you’re not using, the blower will just push harder. Since the air pressure is higher, the leakage is greater. Depending on what kind of fan you have, different things happen, both of them bad. (Source: Are smart vents safe?)
Despite the bad reputation, I started playing with my “dumb vents” to see if they actually can improve my situation. Sure enough, closing vents in Master Bedroom lowered the temperature in our bedroom while increasing my son’s bedroom’s temperature. But doing so just turned my son’s room into an oven and our bedroom into a freezer.
Being able to shift the temperatures by closing the vents was enough to convince me to replace the “dumb vents” with motorized Keen Vents.
Two weeks later, the temperatures in our bedrooms looked like this:
Using vents cost me less than a 1/3 of what I would have paid to add new zones. I used 10 vents and four SmartSense Motion sensors.
Buying and connecting the vents to the ST hub didn’t give me the control I needed to normalize the temperatures. Luckily, @mike_maxwell was in the process of developing a smart app to control his Keen Vents, so I used his soon to be released Keenect Smart App, which really enabled me to control the vents
Thanks to SmartThings’ flexible platform, the Keenect App coupled with @bravenel ’s Rule Machine and combined with a mod version of @slagle’s Thermostat Mode Director I was able to solve a six year old problem at a fraction of the cost!
As for damaging my HVAC system, during my yearly HVAC check-up, the technicians confirmed that my “climate control system” has no effect on my heat pump. In fact, both technicians said that will stop by Lowe’s to grab a few vents for their homes.
* data courtesy of @mike_maxwell 's in-app report in upcoming Keenect Smart App
Project Timeline
Day 1 - 3
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Replaced all of the vents in the bedrooms
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Connected vents and sensors to ST and installed smart app
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Temperature Sensor Calibration - set four SmartSense Motion Sensor on my desk and compared their temperature readings against an AccuRite sensor over a 2 days period. I thought for sure the results will be all over the place, but to my surprise, the ST sensors were within 1-2 degrees off compared to the AccuRite and even more surprising, they were constant among each other. So I was pretty happy.
I installed them in places away from the vents at similar heights. I also, went back into the old ST mobile app, which I had on my tablet and changed the settings of the sensors to show temperatures instead of motion. I created a room called “Climate control” and that’s my “monitoring dashboard”
Day 3 - 10
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Modified device handler for the SmartSense Motion sensors to report on 0.1 temperature changes
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Fiddling with vent opening. The smart vents allow you to set the opening of your vents from 1 to 100. At first, I thought that open/close it would be sufficient to balance the temperatures. But as the days went by, I learned that the level of opening is very important.
There are many variables to take in consideration when attempting to shift hot air from one room to another. Here are some of the things I had to deal with:
- temperature on first floor influences the second floor’s temperature.
- temperature raises when room is occupied (varies based on room size)
- vent opening in one room is dependent on the vent opening in another room - I noticed that I cannot adjust one room without changing settings (up/down) in other rooms - this one was the hardest because it depends on which room is first/last on the main duct.
- one open/closed door changes temp in other rooms
