this kind of optic fiber is probably only plastic so for a full DIY , you can use also fishing wire with a big power led or an old chistmass tree optic fiber lighted.....
Nice project
manufacturers datasheets, RF appnotes etc all mention this, with results for different usecases (like gnd plane size etc). I mentioned it a few times on the forum:
nothing under or near antenna (keep out zone)
their matching circuit, and CE/FCC certif are based on their development boards+their antenna if external, often without enclosure.
there are a very few pcb antennas which are resilient to untuning. ceramic or meandered pcb are usually more compact but less resilient (like when you approach your hand and device suddently has better or worst communication)
once you change any of these parameters (board shape, gnd size, enclosure etc), it breaks FCC, and may need retuning, still you can get useable range.
"ideally" tuning should be done once enclosed for example. manufacturers can't cover all cases.
on my side, I try to follow these rules. and when interested in a design or a device, I check this. Mainly the routing+gnd, antenna choice, keepout zone, and orientation vs my usecase (long range needed or not for example)
You would use PID if you have a temperature feedback from the rooms, but in your case you are not interested so it doesn't matter much. Sure turning off pump when not needed is a good thing. I have colleague that also bought a few netatmo devices to control floor heating of some zones of his house and he is very happy.
What I didn't quite figure out was how it operates independently as a regular light switch.
What I find most interesting is that this is 8 years old. There have been some incredible advances in the IoT world in that time. I was about to do a similar thing which morphed into an ESP-12F then added a touch screen. I call it the Universal Light Switch
Imagine this: All the switches are identical. Any switch can easily be configured to control up to five devices ... and then changed, on-the-fly, to control a different set of devices.
My design is part of a system that would require a controller (eg. Home Assistant), an MQTT broker, and receiving modules in the devices being switched. It's WiFI which assumes an access point.
The DIY ULS is under $20 and the off-the-shelf receiving modules are under $10. (About the cost of a non-networked dimmer switch) If one doesn't have the controller and MQTT broker, they can run on an old (5 years?) computer (which is cheaper than an old RasberryPi).
This project is a good one!
OSD
@kimot in theory you might be right, but in practice... it just works. The propability of collisions is extremely low and this is, as far as I know, the only problem you can worry about. After all, it was not my idea to use MySensors with RS485:
https://www.mysensors.org/build/rs485
