Control HVAC when windows open

looney2ns

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My daughter purchased a rental condo and would like to have a way to shut off the HVAC when a door or window is left open too long.
Of course I could go with wired door/window contacts + relay route, but trying to avoid that if possible.

There is a Nest thermostat on premises, is it reliable to use say z-wave contacts to control the thermostat in some way?
 

DsineR

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Looks like Nest Detect senses window & door status, which sets alarms but unsure if that can be set to trigger the HVAC.
You mentioned 'too long', meaning a timer would also need to be involved in the process.
Not a Nest person, hopefully someone with experience can chime in.
 

SamM

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My daughter purchased a rental condo and would like to have a way to shut off the HVAC when a door or window is left open too long.
Of course I could go with wired door/window contacts + relay route, but trying to avoid that if possible.

There is a Nest thermostat on premises, is it reliable to use say z-wave contacts to control the thermostat in some way?
Hi

Although I have limited Nest alarm experience, most alarm systems work on the same principles.

I can explain the solution with a DSC system that could give you direction on Nest.


Firstly, you would program the doors and window contacts to form part of the same partition on the alarm (eg partition 1). Then you would program the output (PGM 1) for a "not ready" state, ie when a zone on that partition is open, the output will "low" programmed on the panel output configuration alternatively the PGM output will be high when all zones in that partition is closed. You can change the state of the output to align to your HVAC. Use a 12VDC relay to control the HVAC input to start or stop.

Hope that this helps. Shout if you need any more clarity or if you want me to post you a diagram.
 

eeeeesh

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I think you have a couple of options with Z-Wave, but it is going to depend on the HomeAutomation system you use. I am using HomeSeer

So you would have z-wave sensors on the door and windows you are concerned about. The easiest way at that point would be to just have a z-wave outlet that your HVAC controller plugs into. Homeseer detects the door/window is open and after x amount time, turns off the power. Once the door/windows are closed, power to the unit gets turned on again. Another option would be to use a dry contact type sensor working with a relay. Signal gets sent to the sensor, it trips the relay which is wired into one of the low voltage wires to the thermostat, breaking the circuit.
 

Old Timer

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Way back in the dark ages, we used a system a bit like this on an 24 hr operators room. (Telephone company)
They ran the thermostat up and down like a yo-yo, one would be hot and open the window, one would be cold and turn on the heat.
We used a thermostat in the return air duct to limit the heat by leaving the fan on, but killing the gas when the temp got to 72 deg.
Another thermostat to limit the AC to 75 deg by leaving the fan on and killed the compressor. Leaving the fan on let them think
the system was still working and would not turn in a maintenance ticket.

We picked up 2 cheap thermostats to mount inside the return air above the filter for the limit switches, wired into the thermostat wiring.

The doors and windows were on a 5 minute timer, if they were open longer then that the whole heat/AC went off
and a red light went on above the thermostat.

We found a delay on make that could be set for out door/window switches. This used a DPDT 12v DC relay that opened the wires on the thermostat, and closed the contacts for the red light.

I am sure it could be done with Z-wave sensors and a home hub, but I'm not that versed on it.

The home seer was based on a Raspberry Pi, so you should be able to build your own and program accordingly.
 
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concord

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Not familiar with the Nest eco-system, so I checked out to see if there is an API. There used to be one from Nest and some hubs were able to communicate with the Nest thermostat. However, Google moved Nest under the Google Assistant API. Checking Home Assistant and Hubitat web pages, it looks like that broke access to Nest devices. Maybe someone with more experience with Nest can chime in.

I was going to suggest an automation hub (Hubitat, HomeSeer, Home Assistant, etc) with an automation to sense if the doors/windows are open and adjust the temperature up/down, depending if it is in cooling/heating mode.
 
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th182

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I use Home Assistant for all of my control. It connects to my DSC alarm and my Honeywell thermostat. If the door is left open too long and the AC is on it turns it off. Once the doors close for a few minutes it sets the thermostat back to Cool mode.

I prefer to have the thermostat setting changed (Off/Cool/heat/auto) as I believe the thermostat has timers so it doesn't cycle the air conditioner too quickly.

I use the same principal for my generator as the AC puts it towards it's limit. If the generator senses power failure home assistant turns off the AC at the thermostat. Then when utility power returns it kicks it back to it's previous setting. The generator is a portable electric start one that is left plugged in and I use a raspberry pi to start it and activate the transfer switch as needed. It sends MQTT statuses to home assistant.


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Looney... you would love Home Assistant / Home Automation stuff. I would be digging deep into the bowels of both if not for some summer projects right now that are ongoing (landscaping, retaining wall, new fence, etc).
Home Assistant is FREE, btw. And does integrate with Blue Iris.
 
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I posted this on the Homeseer forum.

We have motion sensors around the house such that when we enter a “zone”, depending on the status of the house, lights stay off, turn on to 100%, turn on to 50% or turn on to 10%.

Here is an example of when we last physically touched this switch:

B86502A0-8421-47F3-ACC4-6A8C6222153B.jpeg

If a window or door is opened on either of our two floors (we have a thermostat for each floor and dampers to control the flow of air) for more than 5 minutes, the respective thermostat is turned off. When all windows and doors are closed on 1 or more floors, the thermostat goes back to “auto”.


Our laundry room is on the second floor. When either the washing machine or dryer stops then an announcement is made on our Sonos speakers that one or the other has stopped. Huge WAF.

When a person is detected at the front door an announcement is made. Great for when deliveries are made and the doorbell is not pressed.

When the doorbell is pressed, a bell sound is played throughout the house (we cannot hear the doorbell from some of the upstairs).

In our great room we have a tablet displaying most of our cameras from Blue Iris. If we are in a room and want to see what our cameras are streaming, we ask Alexa to “turn on cameras” and the TV in that room turns on if off, then switches to the IP Camera Viewer app on the TV which is used to display the streams from our cameras.

In each room a ceiling fan turns on at various speeds depending on that room’s temperature - great when sleeping. Can save a couple degrees of A/C energy.

All closets and pantries have a recessed z-wave sensor. When the door is opened the light turns on. When closed, the light turns off.

All exterior doors have the same sensors and our sliding doors and windows have various sensors. When an exterior door is opened and is open for more than a minute, an announcement is made stating that the door is open. We have interior cats.

During the hours of 10pm to 30 minutes before sunrise, if motion from a person is detected outside from any of our cameras, our exterior lights and RGB lights in our eaves turn on. After 5 minutes of no motion, they revert to 10% and the eave lights turn off.

For Halloween, the eave lights run the lightning routine. During the Christmas holidays, the eave lights are our X-mas lights.

When we are driving home and enter a geofence an announcement is made that [name] is nearing home. When we enter our home geofence, the garage door opens (great for my Acadia because I have not been able to train its garage door opener to pair with our garage door).

When we exit our home geofence and no one is home, if a door is open we get a Pushover message. If one of us (won’t say who) forgets to close the garage door after leaving our home geofence, it is closed.

When the house goes “vacant”, the heat and cooling set points are adjusted to save energy. When we enter a geofence about 5 minutes from home, the set points are set to our ideal settings. Also, all exterior locks are checked to see if they are locked when “vacant”. If not, then they are locked.

When we are on vacation, various TV’s and lights are turned on to simulate our home being occupied.

If we spring a leak in the laundry or bath rooms or kitchen, the main water supply turns off along with the recirculating pump (so it doesn’t burn up). We can then open the valve by asking Alexa to “turn on the water”.

The fireplace can be turned on if the great room is occupied and the house is “awake”. Great for when my wife who likes early morning yoga wants to take the chill out of the room.

When the outside gate is opened or closed an announcement is made.

Our sprinklers adjust the time they are on based on a weather adjustment based on our local weather station data. In Nevada there is an an old Mark Twain saying: Whiskey is for drinking and water is for fighting over. Water is expensive here.

Our address sign turns on about 30 minutes before sundown and off 30 minutes after sunrise. Our exterior lights do the same.

Our blinds are automated and open or close based on sunrise/sundown. We also have mini motes to open or close them as well as being able to control them with Alexa.

Based on Randy’s calendar event, our bedroom Sonos doesn’t make the usual “Today is [date] and the time is [time]” - different days have different wakeup times. If it is recycling day, that announcement is made and we have various visual indicators that we better make sure we get the can to the sidewalk.

There is more...but I’ve been too long winded already.
 

th182

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I posted this on the Homeseer forum.

We have motion sensors around the house such that when we enter a “zone”, depending on the status of the house, lights stay off, turn on to 100%, turn on to 50% or turn on to 10%.

Here is an example of when we last physically touched this switch:

View attachment 67167

If a window or door is opened on either of our two floors (we have a thermostat for each floor and dampers to control the flow of air) for more than 5 minutes, the respective thermostat is turned off. When all windows and doors are closed on 1 or more floors, the thermostat goes back to “auto”.


Our laundry room is on the second floor. When either the washing machine or dryer stops then an announcement is made on our Sonos speakers that one or the other has stopped. Huge WAF.

When a person is detected at the front door an announcement is made. Great for when deliveries are made and the doorbell is not pressed.

When the doorbell is pressed, a bell sound is played throughout the house (we cannot hear the doorbell from some of the upstairs).

In our great room we have a tablet displaying most of our cameras from Blue Iris. If we are in a room and want to see what our cameras are streaming, we ask Alexa to “turn on cameras” and the TV in that room turns on if off, then switches to the IP Camera Viewer app on the TV which is used to display the streams from our cameras.

In each room a ceiling fan turns on at various speeds depending on that room’s temperature - great when sleeping. Can save a couple degrees of A/C energy.

All closets and pantries have a recessed z-wave sensor. When the door is opened the light turns on. When closed, the light turns off.

All exterior doors have the same sensors and our sliding doors and windows have various sensors. When an exterior door is opened and is open for more than a minute, an announcement is made stating that the door is open. We have interior cats.

During the hours of 10pm to 30 minutes before sunrise, if motion from a person is detected outside from any of our cameras, our exterior lights and RGB lights in our eaves turn on. After 5 minutes of no motion, they revert to 10% and the eave lights turn off.

For Halloween, the eave lights run the lightning routine. During the Christmas holidays, the eave lights are our X-mas lights.

When we are driving home and enter a geofence an announcement is made that [name] is nearing home. When we enter our home geofence, the garage door opens (great for my Acadia because I have not been able to train its garage door opener to pair with our garage door).

When we exit our home geofence and no one is home, if a door is open we get a Pushover message. If one of us (won’t say who) forgets to close the garage door after leaving our home geofence, it is closed.

When the house goes “vacant”, the heat and cooling set points are adjusted to save energy. When we enter a geofence about 5 minutes from home, the set points are set to our ideal settings. Also, all exterior locks are checked to see if they are locked when “vacant”. If not, then they are locked.

When we are on vacation, various TV’s and lights are turned on to simulate our home being occupied.

If we spring a leak in the laundry or bath rooms or kitchen, the main water supply turns off along with the recirculating pump (so it doesn’t burn up). We can then open the valve by asking Alexa to “turn on the water”.

The fireplace can be turned on if the great room is occupied and the house is “awake”. Great for when my wife who likes early morning yoga wants to take the chill out of the room.

When the outside gate is opened or closed an announcement is made.

Our sprinklers adjust the time they are on based on a weather adjustment based on our local weather station data. In Nevada there is an an old Mark Twain saying: Whiskey is for drinking and water is for fighting over. Water is expensive here.

Our address sign turns on about 30 minutes before sundown and off 30 minutes after sunrise. Our exterior lights do the same.

Our blinds are automated and open or close based on sunrise/sundown. We also have mini motes to open or close them as well as being able to control them with Alexa.

Based on Randy’s calendar event, our bedroom Sonos doesn’t make the usual “Today is [date] and the time is [time]” - different days have different wakeup times. If it is recycling day, that announcement is made and we have various visual indicators that we better make sure we get the can to the sidewalk.

There is more...but I’ve been too long winded already.
Wow! Now I want to buy more stuff!! You should post another thread with details on your sensors and other components. I have water sensors but no valve. The speakers intrigue me as well as I want to move away from Alexa to something more home automation (and more importantly, privacy) friendly.


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