I am not an expert the wiring used on old boilers with zoning. The circuits are simple so it just a matter of understanding the configuration. It sounds like you have three thermostats each connected to a relay. One relay is different than the other two. The three relays control three independent zone valves. The relays are needed since the values use 120V for operation. How are the relays wired to the boiler and circulator pump? Are there 24V outputs wired in parallel? Now back to your original problem. Are you planning to install a WiFi thermostat on one zone? If so, then I think you are better buying a relay that has a C (ground) wire output rather than switching relays. Another method is to wire a second 24V transformer to the thermostat. There are some YouTube videos showing how it is done. The problem with this method is the the relay and the second transformer must be wired to the same phase of the 120V line voltage. If the are are out of phase then a lot of current will flow through the transformers. They neglect to mention this in the videos.

Vladimir, here are the promised pics. Sorry they are so bad, but it is dark and rainy today. Thank God for cozy greenhouses! I pushed the dracaena out of the way for its close up. The box has a seal along the inside to make it "weatherproof" but the signal comes through just as strong, it seems. I will have to unscrew it to get inside there if the router needs to be reset or anything. This is a view of the back side. I see why my husband peeled off that price tag now lol. I think he mounted it there because it was easiest, not sure if there were any other other reasons. Hope this helps!

I have LG front loads which I love - bought them for the features but not the wifi connectivity, though it offers that. Not long ago I installed the app just to see what it might do (planned to uninstall because of security issues). The app was useless, no real features that I'd ever find remotely useful... and when I walked 2 ft away it dropped out. I did (for fun) attempt to access the app while standing in front of them, and it was too buggy to work. Personally, I'd buy for other features and read reviews, never wifi connectivity. I uninstalled the app as I'd planned. Karen, consider what you might use it for... if you're not home, would you be comfortable adding to the drying time - or concerned about overheating your clothes or dryer? Why start a washer if you aren't home - no one is there to load it and mine is very quiet. Do you just want to know when the cycle finishes? I thought that might be handy but honestly, mine makes a tune when done, and I hear it anywhere pretty much unless I'm working in the yard - and I don't carry my phone there. If I'm not at home, I can't pull the clothes out anyway and put them in the dryer. My dryer also makes a tune, but sometimes I need to remove and untangle clothes. Some offer diagnostics if experiencing an issue, but these same diagnostics are on my front panels. I don't wish to start or stop drying or washing via wifi, so basically, I don't see a good use for such a thing, even without the possible security issues.

I'll try to keep it short, not something I do well. The term for pattern learning, which is also affected by system performance too, is called adaptive recovery from setback. It's also something I also have no need or use for. I do use scheduled daily daytime and overnight setbacks but I got thermostats on which adaptive recovery is an option that can be turned off. I put in two new internet accessible thermostats when I did a two system equipment replacement a few years ago and I got Honeywells (on the recommendation of my HVAC contractor). I'm very happy with them. I need to do a system replacement on a second home in the next few months and I plan to get Honeywells installed there too, so that I can use one app to control both locations. I've heard that some HVAC contractors don't like the likes of Nest and Ecobee. Maybe because some of them are knuckle dragger/Luddite types and feel more comfortable sticking with brands known in the industry, I don't know. I have to say that even with my new Honeywells (the best known name in the HVAC industry and a company that manufactures many OEM branded models - for instance things like Carrier thermostats, Trane, etc) , I had to help a tech program them. The contractor's team did the wiring and of course the equipment install but, frankly, I understood the setup issues better than they did. No problem, we worked together, and the outcome was fine. If your upstairs system is vanilla - single stage gas furnace and single stage air conditioner, a system that doesn't need a communicating thermostat, not a heat pump with backup secondary or emergency heating, maybe an Ecobee or Nest might be fine. If it's other than vanilla, maybe not. And if it's installed or set up wrong, you'll have problems. I'm a person who tries to do things well, which is not always the cheapest way. I like being able to rely on the expertise of others. If you know and can afford to pay an HVAC contractor maybe a few hundred dollars (not counting the cost of the thermostat) for something a DIY person might try but screw up, have one come out to assess your situation and recommend what to use (and what they can install). Most modern thermostats do offer Wifi access and with Apple and Android apps. It shouldn't be too hard. You might even wind up having them install two if you can afford it. Do it at the same time. Your sprinkler controler sounds awesome! Good for you, you old dinosaur! You're an inspiration and excellent example for others, including younger others, of being adaptable to new things and using technology as a tool to overcome a disability. In your case, a visual disability, something everyone of Social Security age has to deal with.