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

You can never go wrong with this brand of product. Did the job exactly as needed. I would always recommend this brand as it the most reliable I've used so far

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..

I had a simple 120v contractor controlling my 240v heating units on the main floor. I wanted to add a smart Google thermostat to control the system. I needed a 24v thermostat interface to a 120V switch that could control the contractor. This unit was made to order for my application. Know your system or talk to someone who knows electrical wiring before you order and save the lost time returning items....j

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

Such a nice product, easy to use and very neat

This is a nice sealed unit. I like the indicator light. It was easy to install.

It's been working really well since I installed. It was exactly what I was expecting.

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

I will be using this to turn on the pump for a single zone radiant floor manifold.

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.

Used this to convert a two wire 110V Honeywell Thermostat to the Nest 24V Smart Thermostat for my hot water in floor heating. A little overpriced for what it is and where it is made. However, it is designed in Canada at least. Works well so far as it has been in use for a couple of months now seeing around a hundred or so cycles. Time will tell.