FHT 80B-2 not working with IP-Symcon


I’ve run into the issue with FHT-80B-2.
I’ve configured it in IP-Symcon and I’ve implemented the heating logic (for electrical heating using SU actuator) based on actual temperature and desired temperature readings coming from FHT-80b.
Initially it all worked but after some time FHT-80B stopped sending actual temperature to IP-Symcon. Later, the readings started to come but now I have the problem again. There’s no actual temperature reading coming from FHT for several hours. Some other values (e.g. valve position) are coming.
This renders FHT-80b useless for me :frowning:

Did anybody else encounter this problem and/or is there a solution (apart from throwing FHT80b away)?


The data transmission from FHT via FHZ to the IPSymcon programm is a subject here over and over again.
New announcing uninstall to the Zentale or one and again instal in IPSymcon could help.
However, nevertheless, basically a transference of the FHT functions to the valve, or?
Therefore, one is well-advised if one gives the basic parametres in the FHT.

Greeting Helmut

I try to use it to control electrical device, so the transfer of parameters is not enough. I have my own heating algorithm in place, using FHT for temperature measurement and for setting a desired temperature.

But with its (un)reliability, I will probably switch to thermometer and no display in the room.

Unfortunately, the communication with the FHT80b is not always reliable. When you have several of them, and/or send too many commands to fast after each other, the device can block itself for several hours or even a day.

What I do when the FHT doesn’t seem to respond anymore is sending a GetStatus message to it. Many times it will then update itself properly.

By the way, why are you using your own heating algorithm. The thermostat of the FHT80b seems to work quite well in my experience. I only control the target temperature from IPS and let the FHT regulate the temperature by itself.

So caution is necessary in communicating with the FHT80b. Send as few commands from IPS to the FHT as possible.

The reason for my own control is that I control electrical device, not a valve.
So (in my understanding) I could either:

  • Buy (expensive) 8W which would then turn electricity on/off based on position of the valve set by 80b
  • Live with unreliable temperature measuring by 80b and turn the electricity on/off with SU actor via PC (my current setup). In return, I get a display and a button to set temperature also directly in a room.
  • Give up display and a knob, return 80b (I still can) and buy HMS 100 sensor.

I own a 8W to control my city heating valve and this works quite well. My system works completely independent of my server/IPS.

But what you also could do is, since you mention that the positions keep coming through, is to use the position value to switch on/off your electrical device instead of using the current temperature of the FHT. This is what the 8W also does, only you have to program it yourself in IPS. When you do this, the FHT can still operate as a thermostat using its own algorithm.

I use 7 FHT in my house now and if you ‚leave them alone‘ and only occasionaly send commands to them they operate quite well. What I said earlier, try to use the GetStatus command to order the FHT80 to send its status to IPS. After that quite often the FHT80 communicates again. And as a last resort, decouple the FHT from the FHZ sending device (in IPS) and link it again. But I have had to do that only once in a several months now.

I do not need to decouple this heating from a PC.
My home server has a downtime of 1-2 days/year (broken HW replacement) which is not an issue for this heating as it is not main house heating.
Therefore I’ll give up display in a bathroom and take a „via PC“ route with HMS sensor and SU actor.
This way I will be able to play with the heating algorithm (which I like:)

IMO FHTs would be a way to go if primarily I have valves with few additional electrical heaters which is not the case for me.