[SOLVED] Hacking simple heater control to simple WIFI switch

Greeting everyone,

I am in a rental property with a simple on-off heater controller. Due to the extreme climate, the house can cool down to 10 degrees when I get home from work. I have been considering hacking the switch to attach a simple relay (WIFI) so I can put it on a timer.

My electronics experience is very limited to quadcopter building. I can solder without issues.
I have tested if I short the top and bottom pins of the switch on the left, the heater turns on.


Can I use this device to use wifi to switch my heater on off?

https://www.ebay.com.au/itm/Self-lo...557405?hash=item2cc2ba689d:g:4H0AAOSwhilZZcXh

Due to being a rental, I can't really change my heating system/drill holes in the wall etc and want to keep the budget to the minimum.

Any hints, tips or links to reading material for my education is much appreciated.

Thanks for reading!

It should work. Be careful with the AC switching side of things and ensure the relay and your wiring can carry the current needed by your heater. The relay is marked 10A which means the maximum load if you have 110V mains is 1.1KW and if you have 230V mains it is about 2.3KW. I would allow at least 10% reserve in the rating for safety reasons.

Note also that it only has a single pole switch so it can only break one of the AC lines, if possible, break the 'live' side and leave neutral connected all the time but in any case be aware that the heater is not fully isolated when switched off.

Brian.

betwixt said:

It should work. Be careful with the AC switching side of things and ensure the relay and your wiring can carry the current needed by your heater. The relay is marked 10A which means the maximum load if you have 110V mains is 1.1KW and if you have 230V mains it is about 2.3KW. I would allow at least 10% reserve in the rating for safety reasons.

Note also that it only has a single pole switch so it can only break one of the AC lines, if possible, break the 'live' side and leave neutral connected all the time but in any case be aware that the heater is not fully isolated when switched off.

Brian.

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Many thanks Brian. I will start the project and report back with results.

I have much to learn about what you said so it will take me a little time to understand everything first, before I do anything.

Rebelrebel said:

Many thanks Brian. I will start the project and report back with results.

I have much to learn about what you said so it will take me a little time to understand everything first, before I do anything.

Click to expand...

I believe Brian is thinking you want to use your wifi controlled relay to make/break the high voltage supply to heater. But maybe your temp control switch is low voltage and you plan on bypassing the switch with the relay. If you don't mind maybe you can post a little more information so he and others can give you better information.
Do you plan on turning on/off high voltage to heater. If so can you give the wattage/voltage/amperage of the heater.
Is it a plug in type space heater or a central heating system with low voltage control wiring. If it's a plug in type there are adapters with timers and even thermostats on the market.

Kajunbee said:

I believe Brian is thinking you want to use your wifi controlled relay to make/break the high voltage supply to heater. But maybe your temp control switch is low voltage and you plan on bypassing the switch with the relay. If you don't mind maybe you can post a little more information so he and others can give you better information.
Do you plan on turning on/off high voltage to heater. If so can you give the wattage/voltage/amperage of the heater.
Is it a plug in type space heater or a central heating system with low voltage control wiring. If it's a plug in type there are adapters with timers and even thermostats on the market.

Click to expand...

Hi Kajunbee,

Due to my limited electronics knowledge, I may have miscommunicated in my initial question. Your question is very much relevant.

If I were ask the question another way. I need to able to push the left sided button on the controller (my reading indicates to me that it's a momentary switch; my experiment with shorting the switch for the moment shows me that the heater turns on or off depending on the initial state).

I need to able to push that button using WIFI.

AFAIK, there is no high amperage AC current in this device. It looks like a 'low voltage' [ I think it might be 30V ] heater controller. I will not be going anywhere near my actual heater or working with AC current.

Hope this answers your question and perhaps you could help direct me in the right direction if required. I haven't ordered any parts etc until I read and understand the issues at hand.

Thanks again.

My apologies for misunderstanding. The relay on the PCB is rated for high voltage and current so I assumed you wanted to switch the entire power on or off.

The board will still work if you connect the relay directly across the switch on the controller but you will have to be aware of three potential problems:

1. Relays like the one on that board tend to suffer from contact bounce. They are really intended for switching high power rather than controlling a low voltage, low current signal. The bounce is mechanical, the flexibility of the moving relay contacts makes them spring back as they collide with the fixed ones. There might be a problem if the switch performs a different or alternating action each time it is pressed, the bounce could be seen as the switch being operated more than once. Having said that, the existing switch will also produce some contact bounce so the software in the controller may be able to reject short contact opening and closing already.

2. If the switch does have alternating action each time it is pressed, bear in mind that you have no way to remotely tell what state the controller is presently in. You might send a command to press the button and expect it to turn on when it was already on and you turn it off!

3. That board opens or closes the relay. If the existing button has a repeat action if it is held down, your remote command would have to operate and then cancel within the repeat period. In other words you might have to send an 'on' command and follow it with an 'off' command withing the space of only one or two seconds.

Brian.

Thanks @betwixt for the clarification.

1. For this issue, I think I will need to test it and see. I have no way of knowing whether this feature will be a problem for me.
2. the point is taken and I think I am happy to live with that until such time I can figure out a way to tell whether the controller is on or off.I turn off the heater when I leave home so will have to trust pressing the switch once. Alternatively I think I may set some timers to turn the heater on and off automatically. Unsure how this will work out when we manually intervene for any reason..... Maybe I can use a simple thermostat circuit of my own in conjunction with a relay of the sorts...... More thinking and research to do.
3. The button does not have a repeat action when held down.

I have been searching the interwebs and came upon "inching relay" which seems to fit the bill.

Here is the screen shot and description.


Theme: DIY Smart Home
Compatible System: Android and iOS/Computer System
Supports status tracking: device status timely provided to the EWeLink.
The product enables remote control of home appliances through the mobile application eWeLink.
Supports max 8 enabled scheduled/countdown/loop timers for each device.
Supports WiFi network.
Works with Amazon Echo, Echo Dot, Amazon Tap, Google Home/Google Nest
100% Brand New and High Quality
Voltage: DC 5V/DC 5-32V
Supports remotely turn on or off connected appliance/light.
NOTE:
This product is a wireless switch supports inching /self-locking mode. Users can add the device to the APP eWeLink in order to remotely control connected home appliances or devices. In self-locking mode, customers can remotely turn on/off connected devices immediately.
When in inching mode, customers can have two wiring ways to select:Turn on 1s and then auto-off/Turn off 1s and then auto-on.
The self-lock/inching mode wireless switch has two input voltage supply specifications: 5V and 5V/7-32V. No matter which specification is selected, the functions remain the same.


I was thinking that an inching relay would be a better choice in my use case.

Any thoughts from anyone is much appreciated.

I ended up ordering the switch in my last post just to try out. I will report back once it arrives.

Ok I have good news.

I got the above switch to work. I simply powered it with a 5W 1A mini USB cable and attached the output to my momentary switch which turns on the heater.

With the app (ewelink) I am able to virtually press the on-off button of the heater thus enabling me to time the heater or turn it on or off remotely.

Thanks for your help!