Confused about Boiler Control

[gn1000]

I have Domoticz running on Windows connected to a HGI80. The boiler is controlled by the relay BDR91.
I am interested in Boiler demand and saw that Dompticz has two devices "Boiler" and "Relay", one ( or both) of which I assumed controlled the Boiler relay.
I had expected to see a binary on/off signal but instead, but the only time I see that is when the system is off overnight (Zero) or first start up in the morning(100%). For the rest of the day the signal shows a number of values between these two. Since there cannot be any proprotional control, I don't understand what I am seeing.
Can anyone help?

[DanD]

Hi,

All the Evohome switch devices in Domoticz are read only and simply show their heat demand values (0-100%). The heat demand values do represent TPI (proportional control) and rather than the BDR showing a binary on/off value it reports these TPI values.

[gn1000]

Thank you for the reply. Do you know if there is a threshold for the proportional control which switches the boiler relay?

[DanD]

Hi,

I think any value > 0 will trigger the boiler to fire for at least a few mins during each cycle. I think the BDR converts the demand into the appropriate on/off frequency of its relay.

Dan