Nest Thermostat High Voltage Hack | Installation [High Voltage Conversion]

I am a licensed electrician that specializes in commercial building automation, lighting controls, fire alarm and security systems. I enjoy my work and these type of gadgets intrigue me.

My Home:

I live in a townhouse style of condo which has 3 thermostats that controls a local 240v unit heater. It's about 1,100 sqft and was built in the 80's.

My Problem:

Programmable line voltage thermostats are expensive and "smart" thermostats do not exist.

WARNING: THE FOLLOWING CONTENT IS FOR INFORMATIONAL PURPOSES ONLY

My Solution:

Parts:

Aube 240v Relay (RC840T-240) - integrated 24v transformer (C, W, R)

Wiremold 2G Box (BW32)

2G Blank Cover

Nest Thermostat

18” 18awg wire

Tools:

Screwdriver

Tweaker Screwdriver
Wire Strippers

Volt Meter

Step 1a-

Pulled the old thermostat and confirmed voltage

Most wall heaters should be 208v or 240v. I took notes on which wires I measure voltage (line side).

Step 1b-

Disconnect the power.

Step 2a-

I put holes in the 2G cover plate to match the wall plate adapter.

I don’t know if I needed the “horizontal” holes cut but it could't hurt… (Although I can see the edges if you know what to look for)

Step 2b-

Mount the Nest backplate to the drilled out cover plate

Step 3-

Install the wiremold backplate

The box has several knock outs on the back, specifically mounting it onto a 1G box. This adapts the 1G into something larger to hold the relay AND something to put the thermostat onto.

Step 4-

Install the relay

Line (Incoming power)

Load (Heater)

Step 5-

Mount the wiremold box

Step 6a-

Wire the backplate/ cover plate

R/W/C are on a terminal block on the relay, use your tweaker

Step 6b-

Mount the backplate/ cover plate

Step 7-

Turn power back on

Step 8-

Plug-in the thermostat

Step 9-

Configure!

I'm sorry about missing a few photos... my phone wasn't cooperating and I didn't realize it until I was putting this together.

My Thoughts:
It's kinda nice. Unit heaters aren't efficient at all but the remote control and the early start is kinda nice. I doubt i'm saving energy (or money).