Hello there. I am stuck with a problem here: I got this
Does anyone know a) Which thermostats are compatible to replace the one shown and are b= usable with HA?
You might have better support if you post the model of your thermostat…
Also please add the brand/model of the HP. Iskra knb is the make/model of the capacitor (electronic component) not of the thermostat.
Alright, the HP is a Rotex HPSU Compact 508 H/C DB-5.
For the model of the thermostat, If I only knew… maybe it’s written on the back of the device, will check tomorrow.
From a very rapid internet search it seems your HP can be managed by a couple of dry contacts relays connected to X1M J60 connector in the internal module PCB.
One relay to enable heating another one to enable cooling, mutually exclusive.
These can be a couple of Shellys combined to a temp sensor to enable HA to implement the logic.
This approach has the great drawback of render HA mandatory to start heating/cooling, a big no in my view.
Another approach would be to search for a smart thermostat that is available in your region/country that has the logic embedded and can be manipulated by HA.
There seems to be also a CAN connection available, but this I think will be more problematic to be interfaced, there seems to be a develompemt made by some fellow Italian here:
I’ll try to look into this but I have a very different system at home so I m a little out of options at the moment.
you could go for something like this:
https://www.aliexpress.us/item/3256801946282669.html
It supports volt free contacts and it seems to support Heating and Cooling.
I’ve got the Fan Coil 2 pipes version and it exposes MODBUS/TCP so I can interface it via simple and native modbus integration
You’ll need to bring power to the thermostat location as it needs main power to function
That’s the way to go…
Quite sure you can accomplish this with common smart relay like Shelly and some HA connected thermometer. Or Esphome dev board.
Is your setup just for heating?
Ps. I’m not a fan of “smart thermostats” so I’m not going to suggest some fancy touchscreen device if that’s what you are looking for…
Touch would be cool. But I have one of those in each room, so I won’t replace them all with shiny touch controls → except it is not more expensive than “normal” smart devices.
In general, I want something that allows me to set temperature and measure temperature in the room. And to control it manually AND by HA, so I can add some rules like vacancy settings and such.
As my HP is to old to be integrated with HA, doing so with the room regulation is the way to go. Also, the current thermostats are extremely inaccurate in the end it is either 23 -25 degree or 19 and below, depending on outside temperature, as they don’t have own temperature sensors. Currently the amount of energy needed to reach a set temperature is calculated by the single outside temperature sensor and standard values from the HP, which is of course inaccurate, especially since the sensor is on north side of the building and we have some offset to average values cause of mountainous landscape here.
So, I need thermostats with own temperature sensors (plus would be moisture sensors as well) and dynamic adjustment to reach the temperature that is selected in the individual room. Btw. this is the device:
From here
It seems a little confusing. You should determine how it’s connected to your hp (which connector/type of activation)
The manual seems to imply that the device gets L and N for power but sends out on the output 220v live but in a PWM mode…never seen the like.
Edit: it seems that the PWM function can be disabled if that’s your case you’re back in game with a smart switch.
You write about individual room temperature control, mut it’s not clear to me how the heating distribution is done in your setup.
Well, each room has its RT 10 which are connected with L/N and control wire, this control wire is ( I assume) controlling the motors on the water lines in that particular room.
Or, the control line goes back to the HP and that is then controlling the motors. I don’t know, but in the end it should not matter.
It is connected with L/N and Pulse ( the black line).
Then sorry I’m not aware of any simple way to emulate the “pulse” of your thermostat (it seems the thermostat gives some kind of signal to the HP maybe a number of pulses proportional to the delta temp between actual and desired temp).
You could try to reverse engineer the protocol analyzing the functioning of the thermostat with a multimeter/scope but it seems an hard task.
Another option could be to investigate if you can interface the HP directly via another connection and see if you can use that instead of your “pulsing” device.
