Yes it is the BroadLink RM4. That’s all you need (besides something to run home assistant on - a raspberry pi would work just fine).Hey OP, I'm glad I found your post. What you've done is basically my ideal setup that I didn't even think was possible with my Castle Serenity.
I see your link or links were removed but from the comments it looks like the IR device you use is the BroadLink RM4, is that right? I think I need to pick that up. I was hoping you could tell me about any other accessories you needed, or which version you bought, or just any general wisdom you could share. Anything would be much appreciated.
The optional USB cable with the temperature sensor is useful to know of your room is warm or not.
You might also want a smart plug to know if the stove’s fan is running or not. I’m mostly using Sonoff S31 smart plugs, which provide power usage data in addition to on/off switching. However, I put an open source firmware on them called Tasmota. This isn’t hard to do, but it does require a bit of soldering… there are some YouTube videos describing the process. Without Tasmota, control of your plug requires going out to some server on the internet which seems inefficient and a little creepy.
I can provide the IR codes for controlling the Serenity if you’d like.