Nest Thermostat troubleshooting

qeldoq — Sat, 04 Mar 2017 02:44:26 +0000

We got Nest thermostats for our house over a year ago. Easy installation (about 15 minutes) and setup. So I figured I would get one for my mother, so she didn’t have to keep walking up and down the long hall to the thermostat to change it when she was hot or cold (or even worse, walk downstairs to change it after going to bed). I put it in… and it kept saying “Delay 3:00” and the house was cold. Now what?

The thermostat will delay heating or cooling if the furnace or A/C has just cycled off, for 3 or 5 minutes (depending on the type of equipment you have), to prevent damage to the system as a whole. See here for more details. Makes sense. But the thermostat would show the Delay, count down to 0, turn on the furnace for 5 seconds, and then Delay again. Repeatedly. I couldn’t figure out what the problem was, and my mother wasn’t willing to give me the time to troubleshoot. So the old thermostat went back on.

After mom’s fall, I wanted to try this again (along with adding security cameras, etc). I put it back in, and it again did the whole Delay thing — but perhaps more importantly, it wasn’t holding a charge.

Now, it was hard to figure out what was *supposed* to be happening. The Nest.com website wasn’t that helpful. The thermostat has an internal battery (as opposed to the AAs in the old White & Rodgers thermostat), and it’s supposed to trickle (re)charge from the existing wiring. But it wasn’t holding a charge, and that also meant it wasn’t staying on-line. The house dropped to 50F.

I spent quite a bit of time with their technical support chat (btw, chat is far better than a phone, because you are running back and forth to the circuit breakers, the furnace and A/C units to see if they are running, etc). After going to second-tier support, we figured out that there wasn’t enough power coming through the wires, and I needed to have a “common” wire attached. Which would require someone to come out and add one.

I called my mom’s HVAC company, got an appointment, and one of their technicians came out. He said that we would need to have an installation team come out to run new wires, but he would see if he could troubleshoot for us, and get us a bid for new wiring if necessary. We did find two unused wires, one of which might be good as a common. He had never seen a Nest thermostat before. I showed him what I could do with mine from my mom’s house. He went to the furnace room, popped off the covers, and the power wire basically fell off of the mounting screw. He fixed that, wasn’t sure what else to do, and I told him thanks and I would deal with replacing the Nest thermostat. I installed it, adding that extra wire — and it said that it had no power on the Rc wire (which it had had before). I took off the “C” wire, and viola, it worked. And it kept the power up! For 4 days. And then the power dropped below the level necessary for the wifi to work. And the house was cold.

I did some more searching, this time for the definitions of the terms Voc Vin and Lin. And found this wonderful article:

What your Nest could have told you but didn’t

You would think that the tech support folks would have asked me what the numbers were for the Voc and Vin, right?
Mine were Voc 35.7V and Vin 14.0V and Lin 20mA. So I have a power drain. It actually gets worse if I try to hook up that blue wire as a common (it may not actually be connected to anything useful).

So… back to the White & Rodgers thermostat. At least for now.

Nest Cam – exterior mounting tricks

qeldoq — Mon, 26 Dec 2016 23:21:43 +0000

We had been intending to add security cameras when we rebuilt the house. But the options available at the time, even with our professional company, were more limited than we wanted. We add a pair of DropCams before our trip to Europe a few years ago, and we now use them to keep an eye on the dogs. At the time, there was no exterior-rated option for the cameras. Earlier this year an exterior version was released by Nest (who bought out DropCam). We put one up in the backyard, also so that we could keep an eye on the dogs. It took about 15 minutes to install, because I had exterior power right under where I wanted it installed.

I wanted to put one at the front door, but I didn’t want to run the power line around the front of the door and windows of the house to the one exterior plug we had available. Nest doesn’t expect you to do anything else, so doesn’t give instructions for how you might put the wires into your walls. I did a quick internet search, and folks have done this, but few details were included. Our neighborhood had a rash of burglaries and package thefts in the lead-up to Christmas, so this moved up on the ToDo list.

I quickly made a 3/4″ and 7/8″ hole in a piece of cardboard, and the plug went through the 3/4 hole easily — so I got a 3/4″ masonry drill bit. It was actually a bit small, and I had to both shimmy the bit and use a file to make the hole wide enough. Given that, and the fact that I had a wall full of insulation, I opted to go directly across (as opposed to trying to run the wire down towards the floor). I got a single-gang box and was easily able to pull the wire across the wall and then replace the insulation around the wire. I found an insert designed for running A/V cables through, where the plug end can be quite big compared to the actual wire, and it worked perfectly.

See photos below.

Key points:

you need a 7/8″ hole or larger to be able to pass the protected USB connector into/out of the wall
it’s easiest to put a single-gang box on the interior side and then use a flexible insert for one of the square switch plates
you need something to fill up the rest of the hole after you run the wire through

Supplies:

7/8″ masonry drill bit
single-gang box (one intended for use in existing walls, as opposed to new construction)
Decora-type single-gang plate
flexible Decora insert (usually found in the Audio/Video section, not the Electrical section)