I have an Altherma 3 EDLA11 and I’ve noticed that the eco schedule for dhw isn’t working. I can see the setpoint drops on the home assistant sensor but if the tank temperature is below the setpoint of 39c before or during the eco window of 4 hours, nothing happens. Even if the tank drops right down to 14c as it did today, the heat pump doesn’t fire up. It heats fine in comfort mode but seems to ignore the eco schedule.
It’s set for schedule only. Did I miss a setting somewhere?
I can’t remember if you are LWT only, or perhaps it was you who advised me to go that way when my ECO DHW wouldn’t run?
If you are using Madoka control, there seems to be/ was an incompatibility with ECO DHW scheduling.
It appears to be yet another quirk of how the wonderful Daikin engineers decided to program the system. According to ChatGPT (after having given it the installer reference guide to look at):
You’re expecting:
“During the eco window, if tank < 39°C → heat”
But the system actually behaves like:
“At the start of the eco time block → perform a heat-up cycle to eco setpoint”
If that trigger moment is missed (or conditions aren’t met), it won’t retry during the window.
So if that’s true, the eco schedule I currently have from 12pm to 4pm should be much shorter. Today, the tank dropped below the eco setpoint at 12:40pm which was after the eco schedule block started. If I had set the block to start at 3pm, then the eco action should have fired.
Another realisation is I’d been using two of the four slots for ‘off’. I’d mistakenly thought that in scheduled mode, it would try to reheat during a window but it won’t. So instead of:
1am - comfort
4am - off
12pm - eco
4pm - off
I could do:
1am - comfort
12pm - eco
2pm - eco
4pm - eco
The schedule is a trigger. So, it looks like with reheat disabled, the length of the schedule slot is irrelevant (beyond the time it takes to heat the tank). Once the setpoint is reached, there will be no further attempt to heat the tank until the next scheduled time slot.
So ‘off’ slots are redundant. The three eco slots would effectively be checks on the tank at those times and if the tank is below the eco setpoint, heat up otherwise ignore and do nothing.