Nest Says Shut-Off Heat Not Its Fault, But Pushes Thermostat Update | Hacker News Reader

Nest Says Shut-Off Heat Not Its Fault, But Pushes Thermostat Update

techcrunch.com

17 pointsswamp4014 comments

Interesting. The problems most people are reporting sound like the trouble I had when I installed my Nests without a common wire: Because my system is wired into an electronic zone box, there's minimal current on the on/off wires that the Nest normally leaches off of to charge the battery.

Nest's tech support helped me find and install a common wire already in the wall; probably the most impressive tech support call I've ever been on, so it sucks they're being overwhelmed at the moment.

My guess is that the new software update pushed the power requirements of the Nest beyond a significant fraction of home systems' ability to recharge it.

Regardless, sounds like a detailed post mortem is in order.

Why does it need to charge? Is there a benefit in breaking the traditional battery-as-backup-only model? If the home has power, the controller has power. If the home loses power, batteries can be put in to retain programs, etc. It seems like they created a problem unnecessarily.

As a plug-in thermostat replacement, the Nest has to rely on the power that's already present in typical home thermostat wiring. That power is more than enough for a typical "dumb" digital thermostat, and should be enough for a Nest in most circumstances (especially since the display and WiFi don't have to be on all the time). The battery is there for power outages and buffering.

A dumb digital thermostat needs no power from the house, there's usually a small replaceable battery (like a 9V alkaline) to drive the relay and switch the control wires. The even dumber mechanical/mercury ones worked totally without power.

Not every system provides the 24VAC red/common wire from the HVAC unit to the thermostat. There is a small amount of current between the hot wire and the control input, which is why you can't usually use solid state triacs/SSRs in a home thermostat. You need an old-fashioned contactor relay.

Twoodfin is referring to the Nest parasitically drawing current from those control wires to charge the battery.

There's a vast amount of experience regarding sophisticated controls for commercial HVAC systems. Systems should be tuned for individual locations. Once they are working, leave them alone until data from the actual installation indicate a need to change. It is not uncommon to lock up sophisticated control systems and only provide a key to trained personnel. If needed, untrained staff get access to placebo thermostats.

Allowing a smartphone to interface with a thermostat makes some sense. Automatic firmware updates to smartphones make sense because the networks to which they connect change.

A thermostat, however, is not a smartphone. The reasons to change the firmware are a change to the equipment to which the individual device is connected, to fix a dangerous bug, or when the new firmware is the only way to tune an individual system which has become untuned.

They are taking a beating on their facebook page over the last few days: https://www.facebook.com/nest?filter=2

Whoever decided to push an automatic (and faulty!) update to a consumer heating controller (during the worst US cold snap in years) should be fired.

Well to be fair, Nest claims their software can save people on their heating bills... and that is definitely happening.

Nest's PR response seems like it's hurting the brand reputation beyond the damage caused by the failure itself.

Software is hard, software & hardware in a closed system is harder, software & hardware with physical sensors and variable, external analog interfaces is even more difficult. The Nest responses seem like they could be "technically" true. However, Nest's overall failure seems to be the lack of robust enough self-diagnostics to identify bad installs, as well as having weak fail-over behavior.

It almost sounds like Nest needs a backup "dumb" thermostat built into the hardware in the event that the sophisticated portion of the Nest hardware is shutdown for any reason.

Youch. This will become more common I suspect as more things get 'smarter' in the wave Internet of Things. It suggests a certain core competency in testing, fault analysis, and fail "sage" techniques. One the most impressive folks I ever interviewed for a QA position was a guy who wrote satellite software that controlled the positioning motors. The guy was seriously (and reasonably so) paranoid in his approach to testing!

The Nest celebrates complexity. Now the bill is due.

It's not the Nest that's particularly complex here - it's the goal of achieving 100% compatibility with every furnace, boiler, heat pump, or HVAC system on the market or was ever sold in North America for the last 50-75 years.

Microsoft had this same problem with Windows, if you recall. You had legions of legacy systems and DOS 5.0 programs that had to work on the new version. Flawlessly.

Anyone can rig up an ARM SoC to a screen, probe, and relay and call it a system. What Nest is trying to do with the thermostat (by taking the complexity burden off the customer) is not trivial.

This problem has been solved for many years. Thermostats and HVAC equipment have what Ableson and Sussman describe as "conventional interfaces". That is why The HomeDepot does not carry model specific thermostats, and people installed Nest thermostats in the first place.

The complexity is solely introduced by Nest.

https://nest.com/thermostat/installation/#thermostat-diy-ins...

Our Nest v1 seemingly died last night. Waiting to hear from support if it's related to the firmware issue or not.

Does the clogged air filter line remind anyone else of the infamous Toyota wayward floor mats?

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