Thoughts for multi-zone heating with a condensing boiler

Configuration
1

Hi,

I have a system that will tell me from 4 zones, which ones have a heating demand and I can choose to turn the boiler on.

However I imagine that the more zones I have, the more likely it is for any one of those zones to demand some heat, especially if they don’t take heat from a previous request earlier in the day.
So that could lead to the boiler being on more often, perhaps nearly continuously.

I then took an unexpected direction, and averaged the demand across all zones. Which would effectively turn frequent and short demands into less frequent but longer demands. This Reduces the response, and the ability drive up the temp in particular room.

My implementation is relatively simple.
I’m using OZW 1.6 which supports Eurotronic Spirtz thermostats.
I have events and timers that configure the set points as you would expect (15 at night, 19 in the day, 16 when away at not night)

The thermostats have their own logic, and their valves are opened accordingly.

I then use a boolean entity to model if the value is open enough to qualify as a demand for heat. I use an input_number so that I can adjust this value, typically I find that 20% valve open isn’t far off a usable trigger state. (to reduce hysteresis).

These entities (one per thermostat) are represented in a group.
if any entity in the group is demanding heat, then the group is in demand heat mode, and an automation will turn the boiler on.
When the group is out of demand heat mode, then an automation will turn the boiler off.

The average demand mode is effectively the same,
I create a new sensor that averages the value opening % of each thermostat (add them together, and divide by the number of thermostats (no surprises there))
and then the automation to turn the boiler on triggers if the averaged demand exceeds the input_number high value (10% seems to work ok)
and the automation to turn off the boiler when the averaged demand is less than or equal to the the input_number low value (5% seems to work).

I’m not sure I have problem necessarily that I need solving. Although I am concerned I could be running the system much more efficiently, and that was after-all the main goal in automating it.

Please send me your thoughts,

2

Hello
I realise the original post was quite some time ago but I was wondering how you have found your setup and whether there is any changes you have made since you have been running it.

I have been running a multi zone heating system for a few year (using ZigBee TRV and temperature sensors) a right mess of a node red flow (but it works) but you where right on some days my boiler doesn’t switch off because as one zone stops calling for heat the next starts. Was looking to see if any one had a setup inplace that worked better then mine when I came across you post.

3

There is a very nice solution on zone heating/ heatdemand avaiable for ioBroker.
heatdemand-control
perhaps it helps to program somesthing similar for HA …

as I understand the solution is to weight the demand and only start the boiler if the weight reaches a border. so normally one demand is not enough.

i would be very interested in this.

4

found some corresponding for HA: heatdemand