Logic Needed for Heat / Cool

[joecheech]

Looking for suggestions for programing logic to suspend HVAC when a window is left open for x amount of time, as well as the logic for when the window closes to resume heat / cool mode.  Are people using snapshot?

Have an Ecobee 3 as my thermostat.

Thanks.

 

[Cbell]

I was working through this one as well. I also have ecobee, and thought that I would use a combination of a count down timer and a variable. The count down timer would be used to avoid shutting the HVAC down just because someone opened a window for two minutes. The variable would be used to determine if more then one window is opened, then shutdown the HVAC. If that cumulative variable drops down to an acceptable number which would represent the amount of Windows, then turn the unit back on. I had planned to also add an alert to send a window open toast pop up to the living room and bedroom TVs if they are on, on top of, sending an alert to the T3s and mobile phones if left opened too long. Lastly... I thought I would add logic to change the cool / heat set points based on the increase / Decrease of temperature and Humidity using some of the axxess contact and occupancy sensors. I thought the advantage of adding this logic would be a plus because the sun heats up different parts of the house as the day progresses. But... I haven’t committed to working this out just yet.

 

I do have the snap shot driver but haven’t thought about how I could leverage it. I thought I could pull this off with a Variable / Count down timer and if statements.

 

 

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[joecheech]

Yea, have been thinking about it too. Hoping someone will swoop in with a solution. 

[msgreenf]

Good things come to those that wait...

[TundraSonic]

From prior experience I decided that a button was a better option for us so I just setup a button to toggle the HVAC system (6 thermostats) on/off.  I am looking forward to seeing what greenfield comes up with.

Only our main and lower levels are contacted and we have double-hung and not all of them are contacted for the top sash which is the one we open frequently for fresh air. So, for us, the reliability of relying on window contacts isn't very high.  

[msgreenf]

44 minutes ago, TundraSonic said:

greenfield comes up with.

never said i was doing something here

[TundraSonic]

21 minutes ago, msgreenf said:

never said i was doing something here

I jumped to a conclusion! Sorry about that. Disappointing though

 

[Matt Lowe]

i would do a timer for when any door opens. set the hvac state to off when it expires when it closes start another timer if no other windows or doors are open and then when it expires set hvac back to on. leave it on auto set your temps set and forget.

 

[joecheech]

2 hours ago, TundraSonic said:

decided that a button was a better option

I like this idea.  As I think this through I noted the same issue.  Some windows aren't on contact sensors and they are also the ones we tend to open most.  Think I'll program something here with the snapshot driver.  @msgreenf I'll hit you up to add another instance in my rack room!

[msgreenf]

5 minutes ago, joecheech said:

I like this idea.  As I think this through I noted the same issue.  Some windows aren't on contact sensors and they are also the ones we tend to open most.  Think I'll program something here with the snapshot driver.  @msgreenf I'll hit you up to add another instance in my rack room!

added

[TundraSonic]

Question - What is the snapshot driver? 

[joecheech]

Layman answer - it's a nifty little driver you can trigger to take a snapshot of the state of devices.  System remembers the state they were in and then can revert back to that state later.  Example:  doorbell rings - while you were watching Roku with the lights at 50% in the family room and the rest of the lights in the house / outside are off. 

You program your snapshot driver so that when someone rings, first thing that happens is a snapshot of the current state of the media scene and lights are taken. Then, set a quick delay and have the outside lights pop on, maybe the light in your foyer, maybe the family room lights go to 100%, pause the media scene and bring the IP camera up on screen for 30 seconds so you can see who's there.  Maybe set a timer for one minute.  When the timer expires, REVERT snapshot will bring each device back to where they were - inside / outside lights go off, family room lights go back to 50%, TV goes back to ROKU. 

This is just one example, there are tons of applications.  Search around the forum and talk to your dealer.  I have about half a dozen instances of this driver for all kinds of things. 

For this application - I'll program a keypad button to trigger an HVAC override - It will take a snapshot of what state the Ecobees are in.  When I disengage the override, it will REVERT them back to where they were.  No need to program an "if" or "else" to figure out what mode it was in.  It will just jump right back to where it was.

[TundraSonic]

Thanks. Can you post your code when you're done? I'd like to see how you do it.

[DLite]

On 9/5/2020 at 2:24 PM, joecheech said:

Looking for suggestions for programing logic to suspend HVAC when a window is left open for x amount of time, as well as the logic for when the window closes to resume heat / cool mode.  Are people using snapshot?

Have an Ecobee 3 as my thermostat.

Thanks.

 

I use this approach with our Ecobees, but I don't use the snapshot driver.  My programming logic is as follows:

1. If a window opens, increment the "Open Windows Index" variable by 1, and if a window closes, decrement that index variable by 1;

2. If the "Open Windows Index" variable becomes strictly positive, start a 2-minute "HVAC Countdown" timer;

3. If the "HVAC Countdown" timer expires, turn off the Ecobee in that particular zone of the house;

4. If the "Open Windows Index" variable becomes zero, stop the timer and set the Ecobee to its usual Heat/Cool state.

 

To deal with the problem of temporary Ecobee outages, I also have code that checks every 15 minutes to see if the Open Windows Index is positive and the Countdown timer is not running -- if those conditions are true, I switch the Ecobee off.  On the other hand, if Open Windows Index is zero, I switch the Ecobee back to its usual Heat/Cool state.

Hope this helps. It will be interesting to see what you come up with.