Aube Technologies RC840T-120 Electromechanical Relay with Built In Relay

EDIT: this RC840T-120 works well, no overheating. Have tested with 15A 120V heater with 1400W showing at the kill-a-watt. Using a multimeter, there is 5.6VAC at red LOAD wire, even when thermostat is OFF. Apparently this might be normal OFF voltage, as the other model RC850 manual indicates that the OFF voltage should be <5VAC. So if 5.6V is above the breakdown resistance of the resistor (I think yes for most heaters as it's just a very simple wire?), you will consume 3.6W all the time, even when heater off. Which is 31kWh per year about 50c. I can't tell with the kill-a-watt as the kill-a-watt does not turn on. I use a switch in line, so I can turn off the whole system during the summer. Use gray for that switch and the outlet so it's clear that it's not a normal outlet. It DOES work very easily. Just add black (C common) white (W) & red (R) small wires (I used 14Ga stranded) and join the white and red for the heater to be on. My opinion: DON'T buy a return. Get a NEW one. The "very good" return I was sent did NOT work. The NEW one works great. NO excess heat when running a 15A 120V heater. I have seen more excess heat from a GE extension cord when running 15A than from this. A+++ on the excess heat issue, which is an important issue for me. The other kind of in-line thermostats seem to suffer a lot from excess heat issues (unless people are just wiring the 240V versions wrong, which might be the case. I saw one video where a guy was referring to one of the wires as "neutral") I use another 4 square metal box for it. I don't just hang it off the side of a 4 square box. So I have a 2 gang box with a light switch on the left and a blank on the right and then I have another 2 gang box above that with a blank plate over it, just for this thing and a couple of connections. Although I partly did that because I was anticipating excess heat because you can't even buy an extension cord these days that is rated for 15A that doesn't have excess heat. But there was no excess heat so maybe the hanging it off the side of 4 square box method is OK. Power is proportional to V squared at constant R, so if I was running a pure resistive load, it would consume 0.24% of full power all the time. So 1.5kW resistive heater would consume 3.6W all the time. "if my calculations are correct" For scale, you lose 0.76W in a 2A resistive fuse. So this power loss is like the power loss in 5 fuses. 22A rating is good

Worked great.

This has been working very well for me and was easy to install with the instructions. You should have electrical building experience to install it though. It is installed to a 1900 junction box in my attic and the thermostat wire is ran from the relay down to the Nest thermostat in the bathroom. The Nest thermostat gets the right low voltage to operate and will request the 120 volt circuit to complete through the relay when it calls for heat. The heater is 700 watts. You can schedule the Nest when to call for heat, along with all the Nest options. I'm very happy to have found this relay it was the perfect match and cost for my project. P.S. This is a real review from a real home owner... I will check this review for any questions..

This product enable you to update older, high voltage, cooling system, and heating system to modern low voltage controllers

Controlled by the new generation (white with color display) Nest thermostat. The relay controls a wall outlet where an electric oil-filled radiator is plugged in. We tried several different variations on the settings and the combination kept a 120 sq. ft. office heated perfectly all the time for several weeks now. Nice too that the Nest, via the relay, can learn how long it takes the radiator (relies on convection only, no fan) to heat the room and then, if desired, start the heating process earlier so the room is at the target temperature at the desired time. The relay switch has performed flawlessly every time. The Nest stays completely charged by the Aube's built-in 24v transformer via the common wire. I would point out that only heating can be controlled, but I would think if you also had cooling (i.e.... a plug in window unit) that the same process could be used for it as well (or, for that matter, two relays and wire one for heat and one for cooling). I'm thinking to try a second unit on a room evaporative cooler. If I do I'll update with those results.

The instructions weren’t that great or maybe it’s because I’m not an electrician (though I’m very proficient in electrical work). It took me a while of trial and error to figure it out. But when I finally did, it did exactly what it was supposed to do. Installed my 120v steam baseboard heat thermostat to the relay and from there to a NEST. Works perfect

Exactly what I needed for the following scenario: Indoor pool exhaust fan that runs on 120VAC wired to a manual humidistat. Humidistat runs on 24V which this transformer provides. When the humidity level hits the set level on the humidistat, it triggers this relay close the 120VAC circuit to the pool exhaust fan turning it on. Worked like a charm. I even paid $100 for an HVAC company to come troubleshoot my non-working fan and even they couldn't come up with a solution. It's built solid and looks industrial grade. My only complaint was the manual was really only designed for showing the wiring for a heater, so I had to experiment and carefully examine the wiring diagram to figure out how to wire it for my scenario. I would have appreciated a more detailed wiring diagram that could be applied more universally.

I used this to convert switch off power to a dehumidifier if the condensate pump I have attached triggers the water overflow switch. Works great, easy to install, fully encapsulated until with an indicator LED so you can tell when power is enabled. Nice gadget.

The Honeywell RC840T-120 Electromechanical Relay is a high-quality solution for controlling electric baseboard heaters, convectors, and fan-forced heaters. Featuring a built-in transformer, it seamlessly connects low-voltage thermostats to high-voltage heating systems, ensuring efficient and consistent operation. Designed for 120V applications, this relay provides quiet switching and reliable performance, reducing electrical noise and wear. Its compact and durable construction makes installation easy in residential and commercial settings. Users appreciate its efficiency, ease of wiring, and compatibility with various heating systems, making it a trusted choice for temperature control solutions.

I used this device to connect a Google thermostat to an electric resistance heater.

Commandé 4 unité pour un projet spécifique relié aux thermostat intelligent . Exellent produits je le recommande

I purchased this relay to operate an electric fireplace using an old programmable thermostat I had laying around. Works like a charm. The selenoid in the relay is audible but not intrusive.

Used this to replace a line voltage thermostat with a Nest for radiant in floor heating. It's only been a few weeks, but it's working as it's supposed to.