Emanuel, can you confirm, that your temperature falls 2-3 degrees during 1 day? (from 21 to 18). Because that is not normal in most cases.
When i started to monitor my room temperature i have noticed that 20-21 degree is comfortable for us. And next to the window/balcony inside temperature was 1 degree lower.
There are only two types of controlers: the ones which “does pretend to know” valve position and can learn some routine (uses duty cycles and pwm), they cost 80 eur from danfoss. These can keep temperature realy steady even less than 0.5 degree. And the one which I will buy for 29 eur, in that one there will be 1 degree difference (overheating) I will see how it works for real next winter.
How much do you pay for heating per month? In how many sqare meters are you living?
I thought that for my 40 sq meters at best system can save up to 2-3 euros per month, but gives you comfort. Thats why I told its not primarely for savings, but rather for comfort.
My temperature is within 1 degree (+/-0.5) of the set point during steady state. I turn the heat down to 18C when not in the room or at home. This way you save on the heating bill. When I’m home and in the room it’s at 20C.
I currently have the cheap programmable ones from lidl. They work ok and help me save on the bill. But I either have to set them every day for my schedule or choose a safe point to make sure I have heat when I get home. Right now they turn off at 8 in the morning and start at 16:30 in the living room and bathroom. But sometimes I come home from work at 19:00 (40%) or at 15:30 (10%).
So I wanted to built myself a system which I can control from my smartphone in order to change it from work to make it even more efficient.
For me this seems to be the perfect temperatures. If I let the house cool to 17C, I would have to heat it up to 21C when I’m at home in order to compensate for the colder furniture. It’s a trial and error process to find the sweet spots.
While for the temperature control, that is not hard. I’m a power electronics engineer and I sometimes do control. Any 3rd year student in control engineer can build a decent adaptive pid control for the heaters. It’s not difficult.
The danfoss units are overpriced from this point of view. I used to work for them before my master, what they are really good at and what justifies their higher price is their product support and quality. They invest a lot of money into R&D and they are among the best on the market. Their device may be 10% more efficient, but that is not sufficient for me. They do offer good quality products and awesome support and that’s what they pride themselves with. For me that’s not needed as I am a handy guy and don’t mind getting my hands dirty.
To have the boiler switch on when needed.
have a openhab controlled relay, there are several ways to do it depending on how ‘out of the box’ you want. I would say the cheapest solution is probably something with arduino and relay which would fix this for less than 10€ but requires small programming. In that case you could have a rule that looks if the valve position of the is e.g. more than 80% and in that case switch on your boiler.
For the stability part, the OH1.x has quite a poor design for the networking. major rewrite has been done to make that more stable for the OH2 version. Hope that you will see better stability with that once you migrate.
Indeed the actual refreshing is rather poor. I did attempt to automate this in the OH2 version, but it is still rather experimental. It will change the valve every x minutes, wait a bit than switch back, so the temp is refreshed.
