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Control 240v Electric Heater with ESP8266

lukebouch

Oct 8, 2023
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I'm attempting to build a diy thermostat for a 240v electric heater that is going to be installed in my bedroom. I'm going to be using a ESP8266 or ESP32 running ESPHome. I'm a software developer so the software/firmware side of things I've got covered pretty well but I'm trying to figure out a relay that can handle 240v at 20amps that can be controlled with an ESP. I have some that support up to like 10 amps that I bought from Amazon that have all of the proper optocouplers and stuff to prevent frying the border when the relay open our closes.

Any suggests would be greatly appreciated!
 

lukebouch

Oct 8, 2023
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It's what I do! you're most certainly welcome.
Some of the links to places to source a relay to control a 240v high current load are dead in that thread. Do you have any suggestions of where I can get electronic components for lower voltage micro-controller projects?
 

lukebouch

Oct 8, 2023
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All of the relay modules for Arduino's and ESP's I'm finding online can only handle a few amps at 240v.
 

Bluejets

Oct 5, 2014
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20amps that can be controlled with an ESP.
Use a decent contactor for the heater load and drive the coil of the contactor with a small 5v relay with at least 220v/10A contact rating.
5v relay will need to be driven (simplist way) via a mosfet off the esp output.
Reason for the high current raequirement is the contactor coil is an inductive load.

If it is to be connected to any mains wiring, get it checked out/built by a regestered electrician.
Earthing and insulation tests imperative.
 

kellys_eye

Jun 25, 2010
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Why use a standard relay? Have you not considered an SSR or opto-isolated triac? In this way you can at least offer PID control rather than the simple bang-bang of a relay contact? It would also 'stretch' your programming abilities in a good way!
 

lukebouch

Oct 8, 2023
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I only really want two states (on and off). I was not familiar with a Triac until just yesterday.

I want something that has some type of lug on it where I can just hook up the 12 gauge romex cable that is running to the heated. Everything I’ve found so far looks like it is designed to be soldered to a PCB.

I’m not opposed to using one of the relay modules I already have, and design for microcontrollers, to trigger a larger contractor.
 
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