first topic here, and I’m not sure whether it really belongs here, but let’s find out.
My apartment’s hot water is coming from an old water heater, running on electricity. I do have a dynamic electricity contract, so I could profit from heating the water when the prices are low and lowering the “target temperature” when they’re high.
There’re also a few other things I could imagine setting up:
push the temperature over 65 every 7-10 days
keep the temperature (skip the “heat when cheap”, when I’m not in the area)
But before I can get to implementing some logic, I need a way to control it.
The power cables aren’t accessible for me, it would require permission from the landlord, and regulating the power would mean I need to measure the temperature as well - which there is no port for. Exchanging the heater is also no option.
So I’m looking for a mechanical actor, to fit onto the manual control that I can somehow integrate into Home Assistant (for now I don’t have many devices, some Zigbee plugs for measuring and switching, and the bridge to my power meter). Because of the position of the heater (right next to the shower/bathtub) there are a few additional conditions:
at least splash resistant
ideally run with batteries, I could run a power cable along the wall, but I’d feel safer not introducing 230V in the close vicinity of where I’m taking a shower
To give you a better idea, here’s a picture:
Of course, I did some investigation myself, but the best I could find was controls for pipe valves. So, I am guessing that I don’t have the proper keywords.
I’d be happy about products, hints, technologies / protocolls, alternative strategies, even the proper keywords
Check the manua of your furnace/boiler/water heater as most of this devices do that regularly to avoid excessive legionella growing even when set permanently to “eco” or lower temps.
the type of water heat you have works with the principal of a simple thermostat. You set a “minimum” temperature and when the sensor reports a lower temp it will start heating to the set one and idle again.
That sounds complicated.
An actor turning that big wheel/knob back and forth (on and off)? Not sure if something like that exists out of the shelf and even more if that would be long lasting hardware…
The usual way to go to just control the power to the water heater (=turn it off when energy is expensive) looks like not be possible as you are renting. You probably are also not allowed to add some smart relay into the main junction box (the water heater probably is attached to a own circuit)
Sadly it is too old. There’s no logic or anything inside…
Today I actually found a few useful things:
An example on how to program a servo. From there I am still missing battery power, splash resistance, and the actual mechanical connection of the servo to my “hand dial”, but this is probably where I can start off with: Home Assistant & ESPHome Servo Example (Step-by-Step guide) – Siytek
Maybe I can get some hints for fitting a servo?
About the chip, there’s Sonoff SV for Wifi (but it’s pretty big?)
I also just saw this ESP32-H2 https://www.youtube.com/watch?v=bS9Ch7k_GK0 → But it looks like they are hardly usable, although devkits are now available.
By now I’ve mostly given up on a DIY control for the wheel.
Gonna evaluate whether the old electrical system/fuse box here is compatible to one of the switches for fuse boxes - and whether they exist with high enough amperage…
Turns out - the fuse box is also super old, so no DIN rails or anything really.
But it had a board ( I think not wood but some other material, most likely not flammable) onto which I could mount a small DIN rail. And then I mounted one of these devices onto the rail: (Zigbee version for me) and wired it in after the fuse. https://www.aliexpress.com/i/1005004895813986.html
Doing that yourself (as in: anybody that is not a certified electrician) is illegal in probably most countries and if you’re renting you will also need consent from the landlord. Over here in addition everything was so old, that no electrician would really touch the fuse box because to say “ok this is good now” he’d have to replace basically all of it (+ the lines going in AND out )
But in the end, it works great, I got measurement and switching capabilities. Still need to fine tune my automation (heating the water depending on price levels, using the measurement to check when it heated last). Only downside: there’s 2 LEDs on the device, one in the button for the state can be controlled (on-off / off-on/ off) but one is just for the devices status and that is now constantly shining blue…
