From dyoung@pobox.com Tue Jan 7 01:03:45 2014 Date: Tue, 7 Jan 2014 01:03:45 -0600 From: David Young To: wuna-list@googlegroups.com Subject: if your Nest Learning Thermostat is freezing you Neighbors, We have been using the Nest Learning Thermostat (nest.com) at our house since this summer. It's worked pretty well until just the last few days, when it developed a bad habit of running down its battery. This basically ruined my day, and if your Nest thermostat has the same bad habits as ours, then it will ruin your day, too. Skip to the end for my solution. The Nest thermostat runs on a battery that charges from current on the wires that control your furnace, fan, and air conditioner. Depending which wires are present in your house, the Nest thermostat may have ample current, or a trickle. Ours had a trickle, but it was enough to keep the battery topped-off. When the Nest thermostat runs down its battery, it turns itself off to charge. While it charges, it is not calling for heat from your furnace. So your house cools until the thermostat has charged up enough to start up again. Our thermostat was in a cycle where the battery would charge up to the minimum, then turn back on. Meanwhile the house had cooled. When the thermostat turned back on, the furnace would run continuously, but not long enough to make up for the heat losses before the thermostat ran down its battery and turned off again. This cycle repeated all night, and we woke up to a cold house this morning. (The cycle had begun yesterday or the day before, but the weather was not so bad when the cycle began, so the cycle was fast enough to keep us warm.) THE FIX To make a long story short, the way that I fixed this was to run out to buy a USB cable that had at one end a micro-USB connector, and on the other, a USB connector that plugged into my laptop. (There's full-size, mini, and micro USB. Your Android phone might use a micro-USB connection.) I pulled the thermostat off the wall, and charged it on my laptop. I let it charge for several minutes. I put it back on the wall. Finally, I *turned off the Wi-Fi networking*. Wi-Fi can drain the thermostat's battery quickly, and the latest software for the Nest thermostat seems to break the built-in battery-conserving measures. Now that the Wi-Fi is off, the thermostat has stopped running down its battery, and the house is warming to a comfortable temperature. The long story is too long, but there were a couple of conversations with Nest technical support in there, helpful suggestions were offered but no *solutions*, things got worse before they got better, et cetera. Dave -- David Young dyoung@pobox.com Urbana, IL (217) 721-9981 From dyoung@pobox.com Tue Jan 7 13:55:52 2014 Date: Tue, 7 Jan 2014 13:55:52 -0600 From: David Young To: Subject: Re: Fwd: [wuna-list] if your Nest Learning Thermostat is freezing you > > I tried that, and that's when things took a turn for the worse! :-) I found a disconnected blue wire, and a disconnected black wire. Neither had been connected to my old thermostat, so I had not connected them to the Nest. I read that the common wire was commonly a blue wire, and there was 24 VAC between the blue wire and some of the other thermostat wires, so it looked promising. I connected it to the "C" terminal. When I put the thermostat back on the wall, the red LED started to blink like it was charging, so I left it for a while in the hopes that it would charge more rapidly and completely than before with the help of the common wire. Meanwhile I shoveled the driveway and scoured the web for more information. It got really, really cold inside, but I had hope. The thermostat kept charging, but it never woke back up. After I gave up and charged the thermostat through its micro-USB port, and put it back on the wall, I got an "e23" error. The solution was to disconnected the blue wire from the "C" terminal. Maybe my blue wire isn't a common wire, after all. I think that the root cause of our troubles is the 4.0 software update. The Nest support site hints at a serious power-draining bug involving the Wi-Fi. It seems that they have known about the problem since Dec 8. They're downgrading affected thermostats, including ours, to version 3.5.3. We noted the reboot loop by accident a couple of days before the temperatures went haywire, so I wonder if many more people are not affected by the bug than anyone realizes. Dave -- David Young dyoung@pobox.com Urbana, IL (217) 721-9981