Want to install a Nest at your apartment but aren't allowed to drill into your walls? A few alligator test leads, solid wire, and velcro strips make the install damage-free and very quick and easy to disassemble if needed!
NOTE: In the second photo, I had to install an extra relay because it turned out our thermostat system was a millivolt system and Nest only works with 24VAC systems! If you have a 24VAC system, you won't need the extra relay.
- one Nest smart thermostat
- a bundle of alligator test leads - I used two, but you may need up to ten, depending on your system
- 2 1/2 strips of 3M Command Damage-free Picture Hanging Strips, Medium size
- electrical tape
- home thermostat that is compatible with Nest (check your home system here: https://nest.com/widget/compatibility/)
NOTE: if your thermostat is a 120VAC or millivolt system, it WILL NOT WORK with Nest without a separate relay, AND
SAFETY NOTE: You most definitely should shut off your HVAC/thermostat circuit breaker BEFORE WORKING WITH HIGH VOLTAGES.
Step 1: Prep Your Nest Base Mount
The Nest comes with two separate mounting options: a pretty rectangular plate with a circular indention, and a square metal mounting plate.
Because I needed a gap to run wires through, and because it was less weight, I chose to use the square metal mounting plate. I used the provided screws to attach the Nest quick-connect board to this plate.
With that done, stick the two and a half 3M Command strips to the back of your metal mounting plate. These can support several pounds, so as long as the temperature and humidity in your house don't fluctuate too much, and your wall is fairly clean and dry, these should support the weight of the Nest and then some.
Step 2: Prep Your Wall Cabling
My thermostat snaps off the wall to reveal three wires, going into screw terminals. There was a decent amount of exposed metal on each wire, so I took advantage of that and clipped my alligator cables in.
(1) Use the stickers that come with the Nest to label your alligator leads.
(2) Color-code - use the same color alligator lead as the one that comes out of the wall.
(3) Avoid short circuits! If there are two wires that MIGHT touch accidentally, cover one or both with electrical tape.
(4) Mechanical support - I used the plastic frame to support the weight of the alligator leads. I don't want them to accidentally pull the wall wires out or cause damage to these wires in any way.
Step 3: Connect Nest Base to Wall Cabling
The alligator leads are great for easy removal, but they can't attach to the Nest quick-connects. That's alright, we'll strip the insulation off the ends of some solid-core wire (color-coded to be the same color as their respective alligator leads if possible!), clip them in to each alligator lead, and cover in electrical tape to protect against short circuits.
Now that you know how long your cables are, go ahead and stick the Nest mounting plate in place within reach of the wires. Then follow the instructions in the user manual that comes with the Nest to figure out which pins to connect to which quick-connect pin.
Pro tip: Slide the wires between the metal base and the quick-connect board, and then through the center of the quick-connect base - it takes a little maneuvering to do, but you need to snap the actual Nest on top in the next, final step!
Step 4: Attach Nest. Done!
Wait up -- double-check your wiring first!
Done? Ok -- now go turn your HVAC/thermostat circuit breaker back on.
And we're ready for the final step! Attach the Nest thermostat itself, as per the instructions in the user manual, and it should light up!
If it doesn't -- go turn your circuit breaker back off, carefully detach the Nest thermostat and check your wiring!
Unless your system is like mine, and is actually a millivolt system, incompatible. I'll cover that workaround in another Instructable soon. :)
Useful tip: for extra precaution against the Nest falling off the wall, I used a ribbon to loosely tie the Nest mount to the old thermostat frame.
P.S. If you ever need to remove the Nest, just disconnect the alligator clips from the wall wires, peel the Nest mount off the wall, and reattach your old thermostat!