Evohome + HGI80 & Domoticz users - zones calling for heat functionality?

[Ditbenik]

I just noticed also something else involving the valves. The evohome fires my boiler every 20 minutes. I just payed attention to it. The living room teperature ask for heat, but the accomanied valve is closed. All the other valves are closed too. Now the Evohome asked my boiler at the next 20 minutes to fire up the boiler. It starts to heat. The pipes are getting hot. But.... where does alle the heat goed. It can' go anywhere (except in the bypass) cause all the valves are closed. It seems to me that this is not efficient causing me to spill gas for nothing. It seems that the two processes (asking the boiler for heat and opening the valves) are taking place totally seperated... I think that is not as it should be... It is either way: or asking heat from the boiler and also opening the valves or the valves are closed but than also there is no need for firing up the boiler.

[bruce_miranda]

This was always something that bothered me, and that's why I dragged my feet having the zone valves and boiler controller independently. In terms of your 20 mins boiler firing, check the fail safe option to see if it's enabled.

[DanD]

Hi Dan, i'm pretty new to all this but i've a question which i didn't see discuss. Maybe someone can help. First of all i'm using Domoticz (the latest stable version) on a Synology. My heating system is as follows. I have on the grond floor under floor heating in 7 rooms. They are controlled bij HCE0. In every room there is a DTS92 for temperature management. (On the first floor there are 4 radiators using the HR92). The system is all connected as follows: The Evohome receives the temperatures from the DTS92's. When there is a heat demand it controls the Intergas Boiler by modulation using the R8810A1018. Also the Evohome sends signals to the HCE80 to open the valves of a specific room. Now my question:

In Domticz I see every room temperature correctly also relay's (not always withe the right names, sometimes just called zone especilly the one with ufh). What I don't see are the signals send bij the Evohome to the HCE80. First I thouhgt that the relays for the rooms where those signals, but the device id is comming from a DTS92. I checked this by removing the batteries and then the signal is seen at last by the time I removed the battery. So the relay for example for the living room is not comming from the Evohome but from the DTS92. I'm curious what the Evohome is telling the HCE80. The reason I want to know this is that te relay now asks for a heat demand (even with percentages bigger than 50) but the valve for the UFH is not opened. It seems to be a different signal. By accident i was tryring to rebind my evohome for the living room to the HCE80 by pressing only the bind button on the Evohome and I suddenly saw I new relay (with the same id as the evotouch called living room. I thought: this is the one i'm looking for, but unfortunately in the log i could see it received only 3 times a signal and then it was'n seen anymore. I also tried to do this binding again, and again, but I never could repeat what happened the first time. I hope I made myself clear and maybe someone can help.

Thanks, Hans

Hi Hans,

Unfortunately the HCC/HCE80 isn't fully implemented in the Domoticz code as I don't have one in my set-up. I have spent a little time with another user analysing the messages that this device sends and I think that you are correct and I don't think the HCE80 sends information on each individual zone/valve demand. Instead it only sends the overall demand to the main Evohome controller. I will try and find the posts where I was discussing this topic with another user and see if any of the information helps to troubleshoot the problems that you're having with your Evohome set-up.

Dan

[Ditbenik]

Thank you Dan and Bruce_Miranda,

Bruce, what do you mean by check the fail safe option, where do I find that?

Dan, I think you are right. I saw a relay with a device number that is the same number as (I figured out) that represents the pump of the HCE80. So the relay is coming from this unit. It is always on and represents a percentage (I think indeed the overal heat demand calculated by the HCE80?). Now I see that this percentage is exactly the same as the percentage that is send every twenty minutes (the cycle of 3 times an hour) to the boiler. So it seems that the Evohome itself is not calculating the total amount of heat of the underfloor. The total amount seems to be calculated (regarding the device number) by the HCE80. Maybe the Evohome combines this with the amout of heat needed for the radiotors and sent then the total of that to the boiler. This last thing I haven't checked because the radiotor valves in my house are always closed (so they are not asking for heat at the moment). Am I thinking in the right way?

[bruce_miranda]

Installer Menu, System Parameters. Check Fail Safe is enabled or disabled?

[Ditbenik]

Thank you for your explanation. Now I have another question. Because I think I spill a lot of energy bij firing up the boiler while the valves are closed I had an idea of overriding my evohome controller. Just for an experiment. Ik was looking at the events section in Domoticz. My idea was to read the temperatures. As long as the temperatures are not more then 0.3 degree below setpoint the whole system should be shut down (by giving a command that the controller goes in economy position). Is the temperature lower than I will raise alle temperatures far above setpoint. (this way i will be sure the pump is running and the valves are open). Then when the temperature comes to the setpoint the whole system is again set in economy mode. In my case I think (because are house is very well isolated with an Rc value 8) the heating system will be off most of the day, because cooling down goes very slowly. But when I try to do that by scripting using blocky the only temperature I can read out is the outside temperature (for which I have a device). All the devices for the evo home temperatures are not seen. Is this normal?

[DanD]

Quick Domoticz update:

I've finally fixed the bug which prevented the DHW sensor's battery information appearing in the devices list. The fix has just been merged into the main Domoticz code and should appear in the next beta in a week or so.

I'm working on fully implementing the Opentherm Bridge with Bruce's help at the moment. I'll hopefully have an update ready in the next week or so and it's looking likely that the only information available is the heat demand message (0-200) which gives some indication of the flow temperature (0-min 200-max). I still have to complete some further investigations to confirm this though.

Dan

[dty]

Dan, my DHW is set to 58, but the demand in Domoticz shows as 60. Any thoughts? I can capture you a few messages if that's useful (and you can tell me the message ids).

[DanD]

@dty

Unfortunately, Domoticz doesn't yet know how to request the DHW setpoint and differential so it's just pre-set in the graphs at 60. It's on my to-do list to fix this in the code as the command is known (10A0). It's a little more involved to fix as I need to squeeze the multiple values (setpoint, differential and possibly overrun) into the Domoticz data structure without breaking something else.

Dan

[dty]

Fairy snuff! I'll shut up! Just having the right set-point without the other stuff would be an awesome start and stop me getting confused.

Out of interest, what is the "differential"? I can see the actual DHW value, and it seems like you know how to get the set-point. What else is there?