The install went pretty well. The only real issue was that the builder had put in the thermostat used a 4 wire cable. The 24V, heat, AC, and fan. We have a humidifier which is wired local to the furnace and only takes in to account the passing air humidity.
As some of you who have this sort of hot air system you need to change the humidity setting depending on outside temperatures. This meant that I had to do the settings manually based on the forecast. If you leave the humidity at say 35% and it gets -10 or so you get frost on the windows.......
Anyway the problem was I needed another lead to connect to the Nest. I decided I would just run a two wire cable rather then rewire with a 5 wire cable. The problem was getting the cable run up to the thermostat.
One of my first thoughts was to pull the cable back down with a cord attached then add the new cable and pull back up. Problem was that the wire was run before the sheet rock was on and the installer made sure the cable didn't fall back down in by wrapping it around a nail somewhere up inside the wall. With out making a large hole in the wall there was no way I was going to get that cable loose.
OK tired several other sure fire ways to snag a cord loop draped in the wall... Tried to run a wire snake up, dowel with camera on it to find things...... and well about a half dozen other methods. The final solution was to make a loop that went around the cable with cord attached and attach that to a dowel so it followed the cable up to the hole.
Now I have the cable added and left a cord attached so if this happens to need to be done again it will be a snap.
The humidifier has it's own transformer so I didn't want to chance getting the furnace and it connected together so I put a relay in for isolation. The coil of the relay is attached to the "C" terminal in the furnace and the other side goes to the * on the Nest.
The relay contact is in the circuit of the humidifier solenoid. Got an electrical box to mount the relay in and then patched the duct where the old system mounted and put the box there.
While I was inside the furnace I give it a good cleaning, hadn't done that for a while so it needed it.
All put back together now and programed so when ever we need heat or cool it should be working, didn't actually test it but might do that tomorrow. Today was long enough as it was.
Two of my adult children have the Nest, both like them so I'm going to see how it goes. The old thermostat was programmable which was fine back when I use to work but after retirement we are almost always home and have no set schedule of when we go off places, so it hasn't been "programmed" in years. This new on I can set using my phone so if we turn it up/down when we leave I can always let it know when we will be home and have the temperature just like we want it. That might help save some energy.