Anybody use a Nest thermostat?

[phonedave]

I'm asking this here because we have quite a few automation / tech minded people and maybe somebody can answer.

I had a Nest thermostat installed (by my HVAC guy, he was was here anyway, so why not - so this was installed by somebody who knows what they are doing) sometime over the summer (maybe August). It has been working just fine since then. Cools when I need cooling, heats when I need heating. Does that Nest thing when it determines that despite what I set it to, I would save money at a different temp, etc.

I have separate heating and cooling systems. I have a boiler with hydronic heat, and a standard forced air AC system.

Last night, I am sitting in my living room, enjoying the comfortable heat of my hydronic system, when all of a sudden "why did the AC just turn on?" The Nest was triggering both the heat and the AC at the same time.

The Nest was also set to "Heat" (Not Cool, not Heat & Cool, just Heat). I killed the breaker for the air handler and compressor, which stopped the AC (Naturally) but then the Nest freaked out because "something is wrong, there is no voltage on your Y1 wire". (As an aside, what a great design, in the middle of January you detect something is amiss with the AC, so you lock up entirely). So, to make the Nest happy I put the breakers for the air handler back on, figuring that would stop it freaking out about the Y1 wire, but at least my compressor would not be running. Well that seems to fix it. The Nest was happy about the Y1 wire, and went back to heating things, and not running my AC.

This is next to impossible to google, because all of the searches are about what to do when your Nest runs the AC instead of heat just after an install. I can't find anything about after working nicely for 6 months, it suddenly decides you want both heat and AC at the same time in January in the Northeast.

Anybody ever hear about anything like this? Maybe it was a one time glitch (I hope).

 

[Flying Tivo]

It happend to me once but it was a loose connector on a Relay on the compressor up top. You can unmout the nest thermostat instead of turning the breaker. Cycling is good to reset. Never happened again.

 

[phonedave]

It happend to me once but it was a loose connector on a Relay on the compressor up top. You can unmout the nest thermostat instead of turning the breaker. Cycling is good to reset. Never happened again.

I wondered if that could be it - something with the air handler / control as compared to the Nest itself.

The problem with unmounting the Nest itself is that then I have no heat or AC. My AC and heat are on separate breakers, actually three separate breakers. A 240 for the compressor, a 240 for the air handler, and then a 120V shared circuit for the boiler (the boiler only needs a small amount of power to run the thermostat, the circulator pumps, and some other miscellaneous things like exhaust damper controls).

By turning off the AC circuits, the Nest was still getting power from the boiler circuit, but the AC would not be operational. I was trying to kill the AC, not reset the Nest. I never even though about power cycling the Nest, I was afraid it would stop working altogether.

If it was the middle of the day, no problem, if something happens I can run out to HD, get a old school thermostat, hook it up and have heat. But this was at 10:30 PM (of course that is when these things happen) and I did not want to loose heat in the upstairs of my house (downstairs is a separate heat only zone, with an old school thermostat on it)

 

[JoyfulNoise]

Ahhh, my parent’s old mercury switch thermostat, how I miss those -



They never failed …

Sorry your Nest is being a pain in the tail feathers. Don’t have one, thought about getting one, laughed at the asking price, decided I’m fine with my old, dumb, programmable thermostat. But I’m posting to listen in for the learning …

 

[Flying Tivo]

I was afraid it would stop working altogether.

What i meant as a reset is that the condenser and evaporator reset(nopower) the thermostat itself wont loose any programing.

 

[phonedave]

Ahhh, my parent’s old mercury switch thermostat, how I miss those -



They never failed …

Sorry your Nest is being a pain in the tail feathers. Don’t have one, thought about getting one, laughed at the asking price, decided I’m fine with my old, dumb, programmable thermostat. But I’m posting to listen in for the learning …

Mine was free, or some minimal cost (like $25) from my electric company. There was some energy conservation initiative that covered it.

 

[JoyfulNoise]

Mine was free, or some minimal cost (like $25) from my electric company. There was some energy conservation initiative that covered it.

All good until the gubermint orders the NSA to seize control of your thermostat and forces your home to be no cooler than 82F in the summer nor warmer than 67F in the winter ... but I digress ....

 

[midlifecrisis]

My new home came with the Nest. I quickly replaced it with an Ecobee 3. Nest really wanted to control my climate without intervention from me and seemed to just ignore my settings to some degree or another. I've seen some reviews to support that. I think they are decent units if you want it to just do it for you.

I will admit I had experience with Ecobee in the past, so I was comfortable with it and happened to have one hanging around unused, so I wasn't real interested in a learning curve, but Google is famous for deciding that the end user doesn't need to have control because, well, Google. Their support either via person, chat, or support pages are atrocious.

Also, check your agreement because most energy companies that provide those thermostats with a discount do so with terms and conditions that allow them to control your thermostat when conversation is needed via special firmware. If you are okay with that, then fine. My problem is they aren't really good about communicating those events. YMMV.

 

[ajw22]

I only use Honeywell thermostats and find they do the best temperature control.

 

[RLP]

Nest thermostats are marginal at best with forced hot air, lousy with hydronic heat, and simply do not work with steam.

We will not service an hvac system with a nest thermostat .

 

[phonedave]

My new home came with the Nest. I quickly replaced it with an Ecobee 3. Nest really wanted to control my climate without intervention from me and seemed to just ignore my settings to some degree or another. I've seen some reviews to support that. I think they are decent units if you want it to just do it for you.

I will admit I had experience with Ecobee in the past, so I was comfortable with it and happened to have one hanging around unused, so I wasn't real interested in a learning curve, but Google is famous for deciding that the end user doesn't need to have control because, well, Google. Their support either via person, chat, or support pages are atrocious.

Also, check your agreement because most energy companies that provide those thermostats with a discount do so with terms and conditions that allow them to control your thermostat when conversation is needed via special firmware. If you are okay with that, then fine. My problem is they aren't really good about communicating those events. YMMV.

Yeah, I opted out of all the remote electric company control stuff.

First off, my electric company has nothing to do with my heat. My natural gas supplier and my electric supplier are two completely different entities.

Second, if the elco decided to turn my AC to a higher temp, even for a small monthly savings, my wife would kill me.

 

[phonedave]

Nest thermostats are marginal at best with forced hot air, lousy with hydronic heat, and simply do not work with steam.

We will not service an hvac system with a nest thermostat .

What do they do wrong with Hydronic? Mine seems to work fine (aside from the Heat and AC at the same time incident)

 

[phonedave]

Update. So it did it again. This time at a more reasonable hour, and also when it was not below freezing outside.

Sunday afternoon I again had the AC turn on while the heat was on. This time I had the time to play around with the app. There is a "run fan" setting in the app, with selection for 15, 30, 45, and 60 minutes. I set run fan for 15 min, and then canceled it. That turned the fan off. I am guessing there is some sort of logic in there that decides it needs to run the fan for a while because it needs circulation.

When the temps get higher (like high 50's / low 60's) I'll put power back to the outside AC unit, and if I catch it doing the same thing again (running the fan) I'll check to see if it is also cycling the compressor.

 

[JoyfulNoise]

Good thing your heating and cooling systems are separate. In my home, the gas burner and heat exchanger sits right below the AC evaporator in the air handler. If the heating and cooling were activated at the same time and no one was around to catch it, the heat generated from the gas burner would increase the temperature of the refrigerant in the A-frame and the compressor would likely overheat and blow out in short order. That would be some serious equipment damage ... $4k-$6k easy to just replace the damaged compressor plus the labor and cost to drain and recharge the entire system.

I'd toss the NEST and go to the hardware store and install a simple, not-"smart" digital thermostat.

 

[phonedave]

Good thing your heating and cooling systems are separate. In my home, the gas burner and heat exchanger sits right below the AC evaporator in the air handler. If the heating and cooling were activated at the same time and no one was around to catch it, the heat generated from the gas burner would increase the temperature of the refrigerant in the A-frame and the compressor would likely overheat and blow out in short order. That would be some serious equipment damage ... $4k-$6k easy to just replace the damaged compressor plus the labor and cost to drain and recharge the entire system.

I'd toss the NEST and go to the hardware store and install a simple, not-"smart" digital thermostat.

That is why I have the breakers for the compressor off right now. Running a compressor in freezing temperatures is no bueno for the refrigerant lines either.

I do have a separate C wire, which means the nest can turn on just the AC fan (without cooling) if I set it to (or apparently if it feels the need to). My old thermostat had that setting as well Heat/Cool/Fan/Off