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The Nest Thermostat Rant Page

"I'm surprised at the things that the Nest does not do that a 50 dollar thermostat will do."
-JDB on the Nest Community web site.



It's not too often that I run across a piece of technology that is total and complete garbage. The Nest thermostat is one of those things. If I owned the house in which I live, I would have discarded it a long time ago. The Nest thermostat isn't something that can be fixed with software improvements or updates. The entire design needs to be thrown in the trash and done again by someone who A) understands what thermostats do, B) how HVAC systems actually work, C) who listens to what their customers want and (most recently) D) is not owned by a company who respect for people's privacy is nonexistent at best.

It would probably also help if the galumphing green greenies were kept away from a thermostat's design process as well. That's a rant for another day.


This page aims to go through the various defects present in the Nest thermostat.

"Power Sharing"

Soon as you've taken it out of the box, you'll want to hook the Nest thermostat up. To their credit, Nest tries to make this task easy, by offering a comprehensive pre-purchase "wizard" that asks you a few questions about your existing thermostat and its wiring. What they don't say much about is how the thermostat powers itself. Although there is at least one source of power coming to a thermostat, its only purpose is to allow some sort of switching mechanism to turn on heating or cooling when the thermostat completes the circuit. This power isn't intended to be used by the thermostat itself, which is why any electronic thermostat needs batteries in order to function.

The Nest thermostat, being based on a fairly powerful microcontroller, and having such features as built in Wi-Fi networking, draws a lot of power and could not run for an acceptable period of time with conventional alkaline or carbon-zinc batteries. It has a built in lithium ion battery from which the thermostat is powered, and like similar devices, that battery must have some degree of charge in order for the thermostat to work. This battery has to be charged somehow, and Nest's engineers came up with a "clever" way to do exactly that. Whenever the furnace or air conditioner is not operating, the Nest thermostat "steals" a small amount of electrical power by letting a tiny bit of current flow through the power wires coming to it.

Nest had the audacity to patent this technique. If there ever was proof that the US patent system was seriously broken, this might be it.

Power stealing, in case you've never happened to own an electric doorbell, is not a new technique. Any doorbell system with a lighted button allows a slight amount of power to pass through the bulb in the button, but not enough to trigger the chimes. This approach is needed because there is typically no neutral wire going to a doorbell's pushbutton.

Another use for power stealing is that of illuminated in wall light switches, or electronically operated switches that are capable of sending multiple commands to an attached device. It's very common for there to be no neutral wire in a wall switch box, especially in older construction. Just enough current is allowed to flow to illuminate the neon tube in the switch, or to allow the transmitter and receiving electronics to operate, without causing the load to operate until the switch is actually turned on.

Even garage door openers frequently make use of power stealing to illuminate the door operation pushbutton inside your garage, so that you can find it in the dark.

In the examples above, power "sharing" or stealing actually works. It doesn't work nearly so well for the Nest. Nest Labs made the assumption that most heating and cooling systems would ignore a small amount of power "leaking" through their gas control valves, contactors or solid state control systems. There is some suggestion that perhaps the current draw is "pulsed" in an effort to try and avoid triggering systems where even a small amount of current flow would start them running, with the idea being that no HVAC system can respond quickly enough to the pulses to actually turn on. Many people have seen exactly that happen. Ironically enough, newer HVAC systems with fully electronic controls are more likely to suffer from this problem than older systems where the thermostat is operating a gas valve or contactor directly.

I've actually heard the Nest kick in my furnace for a short period of time, only to shut it down soon afterward. A few times it has done this in rapid succession, which I'm sure isn't really good for the furnace itself. Once I caught the Nest displaying a notice stating that it would wait about two minutes before turning the system on again.

Still others have reported that a long idle Nest, on a rarely used HVAC system, will also run its battery down.

At least this problem can be solved if you're willing to run a "common" (more correctly, a "neutral") wire to the thermostat so it can pull all the current it wants to without accidentally triggering some part of your HVAC system or giving it fits. The bad news is that you'll almost certainly have to run this wire, or pick up a "wire sharing" kit if you do not want to or cannot run a new wire.

Wi-Fi

The Nest thermostat contains a built in Wi-Fi radio. It's supposed to be able to use an Internet connection delivered via Wi-Fi to faciliate remote control and to gather data concerning the weather in your part of the world (if you live in a place where the Nest thermostat is actually intended for sale).

There are several problems with the Wi-Fi hardware that I've noticed.

First, and most crippling, is the abysmal reception. I live in a fairly large house, and my wireless router isn't all that exciting, but it works well in all but the furthest reaches. There's usually even enough signal that I can work in the driveway and still have a connection using any of the computers or other Wi-Fi enabled devices that are floating around here. The Nest thermostat is one floor and a few rooms removed from the access point (a distance of not even 50 feet by walking or as the radio waves fly) and most times it cannot even see my wireless network. There is no other reason for this than truly craptacular design. I don't live in a place where lots of Wi-Fi signals compound the issue. There might be two or three other access points in range, and the Nest has never seen any of them.

Assuming you do get the Nest to connect to your Wi-Fi network, you're in for more fun. If you use any sort of security on your wireless network, along with a strong passphrase, you'll soon find that the Nest only offers one input method. You rotate the dial to each digit or letter of your wireless security key. If you need to change from letters to numbers, or to choose uppercase letters or symbols, you have to move the dial to that point, make the switch, enter what you need and then switch back. This is mind numbingly tedious and extremely error prone. I tried it four or five times before finally giving up on it. It was my dad and brother who persevered and made it work. In the age of easy, well established methods of Wi-Fi network setup and security configuration, this is inexcusable. What year is it at Nest Labs?

There's no web server built into the Nest, no WPS support, or even a way to feed the Nest a configuration file to make this process any easier. The Nest thermostat could even create a wireless network to which a computer could be connected, thus allowing you to access an easy configuration page where Wi-Fi configuration could be performed quickly.

So let's say that you do get your Nest thermostat connected to your network. Maybe it even seems to be working. Well, if you are like the majority of people, and didn't have or run a "common" wire to the thermostat, you might just get to find about another fun "feature" offered by the Nest. The Wi-Fi hardware is understandably power hungry, and therefore has to run from the battery. The software design of the Nest is so poor that if your wireless access point doesn't comply with whatever perverted ideas their "designers" had about Wi-FI and power saving, that it will run down its internal battery trying to stay connected to your network. At that point the thermostat whines and complains about how its battery is dead, the world is ending and so on and so forth...instead of just shutting up, dropping the Wi-Fi link and working to recharge the battery. My dad had to recharge the battery manually from a USB port on his computer to get the Nest to work again after this happened on one occasion.

Nest, in their infinite desire to shift the blame anywhere other than where it actually belongs, says "some wireless routers are not supported". Running on the stock firmware delivered on many wireless routers, I'd believe that. Many wireless routers running on stock firmware are hilariously broken and a lot of it never gets fixed. However, DD-WRT is on their list of "unsupported" firmware. Excuse me? On devices where it is well supported (pretty much anything with a Broadcom CPU and wireless hardware) DD-WRT is the very example of properly functional firmware for wireless routers. It gets most everything right, including a lot of things that don't work reliably or at all on stock router firmware. If your product isn't working with DD-WRT, your product is probably defective.

As of this writing, Nest has released three or four major revisions to its firmware. Despite claimed improvements in Wi-Fi related functionality, not a thing has changed here. Nor have there been any improvements to the entry process for a pre-shared wireless security key.

Ever since Nest Labs jumped into bed with Google, it's probably best to leave the Wi-Fi functionality permanently disabled.

Reliability

There's a lot to say about this. If you take any time to read any of the commentary and reviews on the Internet, you'll notice that a lot of people have experienced sudden failures of their Nest thermostat. I'm not personally aware of any major damages (such as frozen pipes or loss of life) caused by such failures, but it's probably only a matter of time. Some people's HVAC systems have become stuck on or off due to failures in the Nest hardware.

Instead of a relay, bimetallic strip or even a mercury filled bulb, the Nest Thermostat uses a transistor to turn a heating or cooling system on or off. There's nothing really wrong with this approach. I've got a 20+ year old Honeywell Magic Stat that works in the exact same way. Switching through a transistor has the advantage of totally silent operation, without the drawbacks of pollution from a mercury bulb or the slower response time of a bimetallic strip. If the transistor should fail open, however, your heating or cooling system won't run at all. Some Nest owners have reported failure of this transistor in a shorted state, meaning that the system won't shut off. At best, this would lead to a seriously uncomfortable home, at worst it could cause a lot of expensive damage to an HVAC system.

I talked some about the battery operated aspects of the Nest thermostat above. The requirement for the Nest's onboard battery to be functional in order for it to operate is a serious safety and reliability weak point. If the battery goes dead, there's no way for the thermostat to run your heating and cooling equipment--leading to dangerously hot conditions or disastrous ones as a result of frozen and burst pipes. Although regular electronic programmable thermostats also typically use batteries for power, their power demands are miniscule. They can run for years (if not nearly a decade in some cases) from a set of inexpesive alkaline batteries. Every conventional electronic thermostat I've seen will still function even with severely depleted batteries and all of them have given months worth of warnings that the batteries needed to be replaced. Failing all of that, most electronic thermostats have a fallback in the form of bimetallic thermal switches that can trigger emergency heat even when the thermostat has no power.

 Not so for the Nest. Its internal battery only lasts for a few hours, and when it runs out, all control of the heating or cooling system stops. Paired with the fact that many installations will not have a "common" wire present to allow for accelerated charging and Nest's continued insistence that this isn't a "requirement", the potential consequences are again, disastrous. There's no fallback for emergency operation with more basic sensors built into the thermostat's baseplate or something similar. How did this ever leave the testing phase with such a major and obvious defect?


As previously mentioned, the Nest thermostat has updatable software. I'm generally of the impression that when programmers know that software can be updated later, the goal of getting it right the first time takes a back seat to getting the software out the door. With the version 4.0 release of the Nest software, many of their thermostats both new and old ran their batteries down and refused to allow for reliable operation of the HVAC system to which they were attached. Seriously concerned users did everything from trying to downgrade the firmware to simply replacing the thermostat with a simple, far less advanced and much more reliable thermostat of another type. This made the news in a pretty big way and--surprisingly, especially in today's "rapid release" software development world--it took Nest Labs a spectacularly long time to develop a fix. That is inexcusable.

January 2016 Update: Astonishingly enough, Nest Labs did it again, shipping out a defective firmware update that disabled people's heating systems right in the dead of winter. (If you're in the southern hemisphere, make that the heat of summer.) If by some chance you are still using a Nest thermostat, especially after reading this article, throw that junk in the trash and get something better. You'll be a lot happier. I really wonder how long it'll be before someone is killed as a result of Nest Labs' careless design and lack of quality control.


Quality Control

There are some people in this world who haven't learned their lesson the first time around, and so it was that I got talked into installing a newly purchased Nest thermostat for the same person who got one of the poxy things installed in this house. After hooking everything up and turning power back on, I began to notice that the heat pump to which the Nest had been attached was making a very unusual noise. This continued for a while before I figured something had to be wrong.

It turned out that the heat pump's compressor was running without the rest of the system operating. This is a really good way to "slug" a compressor, as in the absence of a fan circulating air over both sets of coils, the refrigerant won't behave as in intended and may remain in a liquid state. Liquids can't be compressed and that's a really good way to seriously damage a refrigeration or heat pump compressor.

I figured the thermostat's infamous system switching transistor was likely to be bad, and a call to Nest Labs confirmed that yes, this was the case. The thermostat's baseplate was also growing quite hot.

I realize that in all fairness, any product will have a few examples that are defective right out of the box through no fault of the end user. Given that a lot of people have reported eventual or immediate failures of the system switching transistor, it seems like Nest Labs should re-evaluate their choice of part, or consider another vendor. Again, this could lead to a lot of expensive and far reaching damage to a structure or HVAC system.

Programming

The Nest thermostat is programmable. It tries to do this automatically, based on the claim that "nobody ever programs their thermostat because it's too hard".

Who knows, maybe it has worked for someone.

I'm not aware of any programmable thermostat that is a joy to program. I've programmed a lot of them, usually without the virtue of an instruction manual. While some were easier than others, it's my carefully considered belief that if you can place a telephone call or send a text message, you can program a thermostat.

Despite the fact that it's installed in a busy hallway in my house, the Nest's "automatic learning" did a hilariously poor job of figuring out what we were doing, and what the temperature should be set to at various times of the day. Somehow--and I can assure you that no one has ever done this because it would be impossible and likely to ruin the air conditioner--it got the brilliant idea wedged in its craw to turn the air conditioning down to seventy degrees on Saturday afternoons. I was resting in my bed during the heating season and was awakened by the temperature dropping after the Nest had decided it couldn't see anyone in the house and should therefore lower the temperature to save energy. I began to think that a learning thermostat was not necessary or desirable.


I finally resorted to signing into their web site, deleting its ridiculous program and replacing it with one that seemed halfway sane. There's just one problem with this. You can't revise the program or even delete it entirely directly from the thermostat. You've got to have a computer, a mobile device with the Nest app or something equally able to access the Internet and communicate appropriately with the thermostat to change or delete the program.

In the time that has passed, I've come to realize that the program I created (for heating only) could stand some fine tuning. It's never going to happen because it is impossible to edit the program from the thermostat and were I willing to endure the sheer taste of pain yet again in an effort to try and get it connected to my wireless network, it'd probably manage to download firmware from Nest released after its acquisition by Google (of which more below). That is not permissible.

Tony Fadell has gone on record to say that Nest would continue to operate as its own company, and not share information with Google. What Mr. Fadell doesn't realize is that Nest isn't his company any more, and he's no longer fully in charge.

Feature Sets

Nest Labs has publicly stated that it is their goal to produce the "best" thermostat, and only a thermostat. Okay, fine. Whatever.

Why, then, does their product not do many things that regular thermostats have done for many years?

Two cases in point: a clock, and operation of the blower fan without having the heat or air conditioning turned on.

The Nest thermostat knows what time it is. It has an internal clock, which seems to be set using Network Time Protocol. Yet unlike pretty much every programmable thermostat ever made, you can't readily see this clock. Nor can you choose to have it displayed alongside the temperature readout. It can be argued that this isn't hugely important, that many thousands of programmable thermostats never have their clocks set to the proper time, and that a thermostat isn't primarly a clock anyway. The convenience of seeing the time displayed at a glance alongside the temperature cannot be disputed, even if there is a clock elsewhere in the room.

In all fairness, it should be said that later releases of the Nest firmware make a halfhearted concession to those who want to see the time displayed. You can push the thermostat's face to retrieve this and outdoor temperature information (delivered from an online weather service).

Some people I know like to run their furnace's blower fan when neither heating or cooling is called for. It can help to circulate air from rooms in a house where windows are open and fresh air is coming in to those where windows are not or cannot be opened.

You can't do this with the Nest thermostat. Well, technically you can, but it requires that you leave the system turned on in either its heating or cooling mode. Thus, even if you have your windows open and are trying to circulate fresh air throughout your house, if the temperature rises or falls to the point where air conditioning or heating would be activated, that's exactly what will happen. Murphy's Law being what it is, you'll likely have this happen when you're not at home and won't be for a while.

Later releases of Nest's firmware offer a change to the thermostat's fan control functionality. Your heating or cooling system still has to be set to either heating or cooling mode in order to run the fan only. All that's been added is a mode to enable the fan constantly or for a certain period of time.

Truth be told, I've held off long enough. I'm going to tell you how I really feel about this. Which means that yes, bad words are coming right up. If bad words offend or upset you, you will want to stop reading at this point.

Just about every goddamned thermostat in the history of ever, has had a feature to let you turn on the fan even when the heating or cooling systems are off. This feature has, as far as I'm aware, been explicitly provided for in the wiring of every low voltage heating or cooling system ever installed. It is as near to a
standard as anything in the HVAC market ever could be, and yet Nest Labs has not in four releases of firmware managed to adopt the standard.

It doesn't matter to me if they ever do so now. I'm not a "tinfoil hat" type, but I trust Google (especially in our post-Snowden world) about as far as I could throw their corporate headquarters. Even if it would happen to connect to my wireless network, it will never communicate with them, or upgrade its firmware ever again. I don't care what they say about running Nest Labs as a separate entitity. (Nest Labs has a little credibility problem of its own, as indicated by their blocking out search engines from spidering their user to user forums. I guess they'd rather you didn't know how much crap people using their thermostat have had to put up with, how many unfulfilled feature requests or even bug fixes there are out there.)

Ultimately, this is what happens when you let idiots design something, or touch an industry that has gotten along perfectly for many years without their "help".

Thankfully, you do have some Other Options if you want a smart, connected or learning capable thermostat. Honeywell offers several models, and another offering from a company known as ecobee all exist on the market. While I've not tried all of these other options, it is my belief that they would HAVE to be better than the Nest thermostat. The Honeywell offerings handle Wi-Fi configuration much more readily by having a built in web server and Wi-Fi network that can be joined for setup purposes, while ecobee offers remote sensors to provide for better input to help the thermostat learn what it should be doing. Reviews of these products suggest a much better overall experience than the Nest offers, for the most part. At least in the case of Honeywell's product, it is also made clear that a "common" connection in your thermostat wiring is required. While not the best news for a person wanting to install a fancy new thermostat right this instant, this does save a lot of hassle and annoyance when the power stealing methodology isn't a suitable approach.

Since this article was written, a basic Honeywell programmable thermostat offering Wi-Fi capability has displaced the Nest. This Honeywell thermostat sits on the wall and does just what it ought to do in every way. It stays connected to my Wi-Fi without incident. None of Honeywell's firmware updates have so far caused an issue. It doesn't short cycle the furnace at any time. (In truth, there's really only one bad thing I could say about the Honeywell: it has no power backup device onboard, meaning that it blanks out if the power fails. While it does remember what it was doing and how it was set before the power failed, it's an especially good idea to turn off a heat pump or air conditioning system prior to the power coming back on, as it may not do so cleanly.)


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Copyright 2014-2016 William R. Walsh. Some rights reserved. Last updated 05/01/2016.