Looks like you have a 'jumper cable' (the one at the bottom, left in the photo, under the red wire (and the white and brown ones); It's blue and shaped in a loop). In that case you have three options: 1) the Nest Thermostat, 2) the Nest Learning Thermostat, and 3) the Nest Thermostat E. All are compatible with your existing system. UNLESS! The only other thing to look for in your existing thermostat is whether or not the existing thermostat has either 110 Volt or 120 Volt printed on it somewhere. Nest Thermostats appear to only work with 240 Volt systems. You can find out and compare each here: https://store.google.com/us/category/nest_thermostats?hl=en-US. That site even has the compatibilit...
If your home has electric heat, it's already wired for 240 Volts. I've never seen nor heard of an electric home with 110 wiring throughout. You DO have some, just not in the heating system. Those electric radiators use a ton of juice. In that case, if you have or know a regular, trusted handyman or friend (or yourself?) who knows how to wire a 240 Volt dedicated line to your breaker panel, you would provbably be looking at about 100 to $150 dollars (US). If you have to hire a Pro, it's about the same--but that's only for walking in the door (front or back). The rest is all extra on top of that--and never call one on a Sunday!--though it only takes a pro about twenty minutes or less. I rewired a 110 Volt outlet to 220 Volt once for my mother's new AC, but it kept blowing the breaker. That's when the electrician was called and explained about"dedicated circuits" to me. Although he DID say I did everything right, but I left wires exposed a bit at the ends. He added that there's two things you shouldn't fool around with unless you're sure. Those, as per him were/are electricity and gas (as in natural gas, not gasoline; I'll add a third--brakes on a car. If a car doesn't start, it's inconvenient. If a car doesn't stop, it's deadly!).
Understand, I am NOT an electrician. I'm just handy and a sort of jerk of all trades. So, unless you are sure of yourself, do NOT do anything that could harm you on my words alone! Good luck with whatever you decide and have a great day!
There's even a YouTube site from Google (https://www.youtube.com/watch?v=xlx2Um6D1Z8) that shows you how to install the Nest (lots of others have videos on YouTube aslo). As long as everything is turned off and you're kind of handy, you should be able to do it yourself. It's not tricky or dangerous. Though it IS a good idea to not be alone during the installation...just in case. Besides, you may need a professional 'go-fer'! (LOL)
Anyway, there is one other thingto look into. Google Nest has a thing called a C Wire. It's $25 (cheaper than any electrician). Although Nest thermostats are made to work without one, and most of today's homes have them already, some systems may need a C wire for consistent power. There's no wiring or putting holes in the wll. It's a pretty straight forward plug n' play kind of thing. You can find out more here: https://store.google.com/us/product/nest_power_connector?hl=en-US
Good Luck and please DO NOT do anything that could harm you on my words alone. I am NOT an electrician. Just trying to help a fellow DIY-er. Have a great day!
