I have a large 2 story house so I have two AC units (they also heat, but I live in Florida, so we only use the heat 1-2 weeks per year). Can someone (perhaps the manufacturer) tell me 1. How the Nest systems work with two independent units (2 nests), and whether they are recommended for such and 2. How the nest unit works with a (basically) only AC system, will the heat tun on in the dead of summer if nest thinks the house it too cold?
Multiple Nest thermostat's work together in that they share Auto Away status. I'm not sure how much temperature coordination they do - then again, the way Nest "learns" your preferences, within a month or two of you adjusting your thermostat it will figure it out. And no, it won't turn the heat on automatically "against your will" - you can control the set points as well as the extreme hot and cold settings that govern the auto switch over, or set it to AC or Heat only so that it won't switch.
Nest has a great support article - "Managing multiple Nest learning thermostats": http://support.nest.com/article/Managing-multiple-Nest-Learning-Thermostats-with-one-Nest-Account
I have a similar setup to yours - two units, one for downstairs and one for upstairs. I have one Nest now on my downstairs unit, and now that the new Nest supports humidifiers, I'm going to get a the new V2 Nest for my downstairs unit where I will be adding a humidifier before next summer. My existing Nest will move upstairs to handle my heat pump. Support for humidifiers was the only thing that Nest was missing, and I'm very happy they have added it! Even with Nest only on one of my units, I've saved almost $300 in the last four months - my first Nest has more than paid for itself. Auto Away and the self adjusting scheduling really, really works.
Final note - if you don't need support for humidifiers, aux heat pump heat, radiant flooring or other version 2.0 hardware specific features you can score the version 1 thermostats at a discount at Lowes and a few other places. My v1 just got updated with the newest software and it now has all the new features except for those that require new hardware - I love this company!
Wow, thanks for the discussion! I was hesitant to invest in the $500 for two of these guys, but since my AC bills average over $200 per month, and up in the $300-$400/mo. range during summer, I just might make the switch. I like the slimmer profile, so I think I am going to get the new ones.
No the app is free from the itunes store. I use the Android app on my phones and tablets and it is free from the play store.If you go to the app store all you need do is type in Nest to the search bar and it will come up. I even have it on my Kindle Fire.
No problem - my summer AC bills are similar to yours, and the feedback and extra control Nest provides has let me easily whack my energy use by 1/3.
If you are cool with the extra $60 or so for the v2 units they do look like they will be lower profile. Although I must admit, the v1 thermostat doesn't bother me as much as I thought it would - even after I moved my downstairs thermostat around a corner to a more prominent location so it would have a better "view" of my downstairs for the motion controller/auto away functionality. Having said that, I'm certainly welcoming the lower profile for my downstairs location.
Most people who have a problem with them either didn't read the directions, or don't live with them long enough to see a real difference, or still try to micro-manage them to some fixed level of expectations. Similar to people who get frustrated with iTunes because for some reason they still want to micromanage folders/filenames instead of just letting the computer do what it's good at - managing minutia. If you just let go of the micro managing and let Nest do it's thing, it *will* work - but you have to be willing to let it "do it's thing".
And while the auto away and scheduling is nice, since the ring that makes up the outside of the thermostat always controls the temperature by default it's really easy to tweak the thermostat on my way out, or change it with the iPhone app - I think I got more savings just from being more aware of my usage via the feedback it gives and being more aggressive in setting the thermostat back. The monthly energy reports as well as the reports in the iOS apps when the app is in landscape mode are also very useful in keeping me motivated :)
The instant feedback with the leaf they give you is also a motivator to encourage energy savings - and if you "play the game", subtle tweaking can lead to pretty substantial savings. That's where I'm really looking forward to having Nest's on both units. That and the software v3 changes for heat pumps look very excellent. Overuse of Aux heat with my previous thermostats was driving me crazy to the point where I finally just lied to the thermostat and configured them to not have aux heat supported. It will be interesting to see if Nest can do it better this winter with the new v3 software. I was looking at a unit called the Plus Maximizer to optimize my heat pump, but the Nest solution seems to be more comprehensive - and cheaper too!