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24V AC
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Intermediate (Installs < 60 minutes)
Aube Technologies
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Relay is Compatible with Low Voltage Thermostats to Improve Temperature Control and Comfort
On/Off Switching Electric Heating Relay w/24V Transformer
Aube RC840T-240 On/Off Switching Electric Heating Relay with Built-in 24 V Transformer
Aube RC840T-240 On/Off Switching Electric Heating Relay with Built-in 24 V Transformer
Item# 300612T
Price: Normally $57.03 
Hot Deal $34.31
Free shipping on orders over $175 - See Details


  • Direct replacement for any brand name relay
  • Built-in 24 V transformer for easy installation
  • Compatible with 24 V thermostats with 2-wire connections (R, W) or 3-wire connections (R, W, C)
  • Immediate relay activation provides improved temperature control and comfort
  • Epoxy-soundproofed relay ensures quiet operation
  • Low current consumption means multiple relays can be controlled by a single thermostat
  • Heating command indicator light gives at-a-glance verification of relay operation
  • Terminal board connection enables easy installation

Essential Info

The RC840T Electric Heating Relay is designed to control a line voltage resistive load from a low voltage thermostat. The RC840T relay has a built-in 24 V transformer and is compatible with 3-wire (R,C,W) thermostats as well as 2-wire mechanical and battery-operated thermostats. The RC840T operates silently and can be installed in bedrooms, living rooms, or any other occupied area without disturbing occupants. On a call for heat, the relay is immediately activated; there is no delay. This increases temperature control and comfort.


What's Included

  • 1x - On/Off Switching Electric Heating Relay
  • 1x - Built-in 24 V transformer
  • Specifications

    Manufacturer Product NoRC840T-240
    Voltage (VAC)240V
    Resistive load (A)22A
    Inductive load (HP)1.5
    Control signal24 VAC / 40 mA / 1.2 VA
    Transformer Ratings24 VAC / 1.2 VA / Class 2
    Ambient Operating Temperature -4°F to 140°F (-20°C to 60°C)
    Ambient Storage -40°F to 175°F (-40°C to 80°C)
    Humidity Limits0 to 95% non-condensing
    Net Weight11.5 oz. (326 g)
    Terminal Wire Size12 AWG


    49 Ratings
    5 star: 67%  (33)
    4 star: 18%  (9)
    3 star: 2%  (1)
    2 star: 2%  (1)
    1 star: 10%  (5)
    Average Customer Rating
    (49 customer ratings)
    Share your thoughts with other customers
    NEIL -- cotati, CA   6/30/2014
    Good - installed with a Honeywell WiFi thermostat. Basic operational test only.
    MICHAEL -- eagle creek, OR   6/9/2014
    Easy to use, self documented, works fine. Would be nice to see it's solid-state alternative offered side-by-side.
    DAVID -- duluth, MN   4/17/2014
    fit well, seems robust construction, good price.
    Rolleston Electric -- granville, NY   4/3/2014
    If you are using this for more than the 22 amps you must use a contactor and just use the nest to power the contactor and let the contactor handle the load. I have done this a few times. A 10,000 watt load will burn these units up because it's 42 amps close to twice what they can handle.
    BRENT -- clayton, IA   3/8/2014
    Very happy with my purchase. They worked as I planned.
    SCOT -- santa rosa, CA   2/21/2014
    Works great with my Nest and a baseboard heater.
    RIKARD -- san francisco, CA   2/19/2014
    Works really well - using this allowed me to instal Nest with 240 Volt baseboard heater, and my electricity consumption halved immediately
    ROBERT M. -- spencerport, NY   2/19/2014
    Shipped fast, thanks. nice product, especially liked the extra touch of a pilpt lamp to indicate "on". Pricing was on the expensive side.
    DALE -- fargo, ND   2/9/2014
    WIFI electric baseboard thermostat works well. I raise the temp an hour before I go home on my android phone. The android or PC software for Honeywell's WIFI thermostats are great for programming schedules into the thermostats. Took a little bit to figure out which wire went where and I had to put a bigger junction box in than the baseboard thermostat had.
    garry s -- winnipeg canada   1/26/2014
    i have a 4800 watt construction heater suspended from the roof of my insulated garage the thermostat worked fine but was in a awkward position to adjust we had an old mercury style thermostat laying around from when we had ac installed so finding this relay at a cost effective price is the cats ass smarthome shipped this the same day i ordered it and received it 8 business days later kudos us postal and canada post
    Gordo -- vancouver, Canada   1/4/2014
    This was exactly what I needed to control 2 electric baseboard heaters with a Nest thermostat. I got the one with the built in transformer, because the Nest works best if it has a 'C' wire, which this relay provides. You'll need a 3-conductor cable between this relay and the Nest.
    LARS -- ithaca, NY   12/31/2013
    Does the trick for converting (multiple) baseboard heaters (common in this part of Canada) into a thermostat controllable system. Note that in principle (not tested) multiple Aube could be controlled from a single thermostat.
    Norm -- Canada   12/17/2013
    Works fine. Nice to be able to hear the relay click on and off when heat is demanded and have a visible indication when the thermostat is demanding heat by viewing the red Led. Not made for 10,000 Watt loads
    JEFF -- red wing, MN   12/15/2013
    very clean installation compared to other relays. really like the indicating light that lets you know if relay is energized. would purchase this product again if needed. product great, shipping very slow...
    ELIAHU -- lexington, MA   12/9/2013
    Product works great with my Nest Thermostat. Indeed completely silent.
    Daniel -- bend, OR   12/9/2013
    This is a follow-up review. I bought two of these units to power two 10,000 watt Ouelette Electric Heaters on separate thermostats. They worked perfectly through one season and then both units failed about three months apart. They activate the heater when the thermostat calls for heat, but then will not shut off, even if the heat is turned off manually at the thermostat, until I turn off the power at the breaker panel. After a time I can turn the power back on and they will again turn on the heater when heat is called for, but won't shut back off. To be fair, I have not called Aube for help. I assume because they worked fine for a time, they were installed correctly.
    TREVOR -- bozeman, MT   11/21/2013
    Allowed me to connect a new 24-v thermostat to an old 120v baseboard heating line. (Removed old thermostat). This worked perfectly and was exactly what I was looking for that no one seemed to know that this device existed. I'm stoked I found it!
    LES -- elwood, Australia   7/7/2013
    Fantastic. Great service. Thanksg
    COSMIN -- alcala de henares, Spain   7/3/2013
    Very good service even for us the European folks. Thank you
    MERRITT B -- dallas, TX   5/2/2013
    Great service and tech support!

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