Hi,
While tinkering with my UFH and trying to develop a control algorithm for my “virtual” thermostats, I ended up here and on other forums and realized I am doing everything WRONG. Shame on me 
I have already read up on as much as I good on related topics, watched all the related heatgeek videos I could find. I get it now, low and slow is the game, and right now the weather is perfect to commission the system and dial in by weather compensation curve .
I seem to have got the right temperature down for the current(2-3c) weather and will try it out during the night when it hits 0c today.
I am currently also at 4c(it does move between 3-5) of TD between in and return flow.
So what I now learned (if its wrong please correct me):
- Low and Slow
- Weather Comp.
- Limit 3rd party intervention
- Low setback
- Use thermostats (or in my case smart relays with temp. sensors that shut the valves)
- Try to at least have one zone running to reduce cycling (if applicable)
Now I think I am nearing completion to a degree, but more questions now arose that I hope ya’ll here could help or at least explain:
- Hypothetically, you discover a perfect curve, that always matches your target temperature @ all outside temps (till heating is no longer needed), does the heat pump then never shut off, assuming that you keep your rooms at a fixed temperature (no setback). COP will be amazing, but what about the actual electrical usage through the month?
- I have discovered that at the moment, 34 degrees is perfect to maintain my house at 22c and with all stats open thats exactly where my house is at. What happens when I want to up the temperature in the guest bedroom to 24c, the system wont have enough power for that, wont it?
- What if my temperature demands change, do I need to go back and up my curve. As far as I saw, the ecodan does not have the best control ux so bumping it all would be a pain, is there a better way to do this? Maybe some thermostat suggestions? Is there an option to even do this via cloud (its a smart home so thats expected)
So from what I learned and if understood correctly my plan is this:
- Make the living room my main, “always”(till the stats close lets say when the sun heats it up) open circuit. Its the largest area in the house, has floor to ceiling windows and has more windows that wall. Is South facing so during the day gets plenty of solar heat (even in winter times if its not cloudy)
- Then use the stats in the living quarters to modulate the temperature as needed. So if a guest comes that likes it cool, he can crank it down to 18, but unsure how this would work if someone wanted it much hotter (hope the question above answer this)
My current setup:
ERST20C-VM2D
No buffer
UFH in all rooms - all set as 1 zone
New Construction
Located in North Italy
Current COP (why I even entered this rabbit hole to begin with):
None for October (first cold is Nov)
2.64375 for November
2.40 for 2022 so far
My previous way of running it:
Temperature sensors in every room report to smart relays that open/close the valves. Since I have direct access to the programming, I dialed in the open/close thresholds for every room, usually about 1-1.2c below is when it opens and closes 0.3-0.4c before reaching target (I came up with these numbers analyzing the data). On sunny days, I only need heating at about 3-6 in the morning (thats now), dependent on how cool the outside is, as soon as the sun goes up, the living room(main area) needs 0 heating and can last about 30-35hours before dropping again to the ON temp for the stat. The bedrooms are behind it, so get way less sun and hence they only capitalize from the solar heat passively.
Maybe theres no reason to go low and slow in my use case at all assuming how low my heat demands are?
Thank you and I cherish every tip
