OK, so I have been testing with the stove the last week. It’s getting how I want it to work
Before the I installed the stove I was using something that is called “city heating”. Most of the houses in the Netherlands just have a gasline coming in, and heating with a boiler / central heating. Unfortunately when a city pans new areas with city heating they don’t install gas. So I’m bound to the city heating monopoly
The only advantage of city heating : turning it on or off is as easy as ON and OFF , no modulating boiler to work with.
Pimatic was controlling a relay that could open or close the main valve for the warm radiator water. To col? Open the relay. Warm enough? Close the relay.
The goal was to heat the living area with the pellet stove and simply don’t use the city heating anymore. To do is, I needed to take full control of the pellet stove.
Before the stove I used a dummy thermostat device where the Setpoint was controlled by a bunch of rules. The rules where following a program dictated by our weekly schedule. When someone stayed at home on a day the programming wasn’t expecting anyone I turned a dummy device called “today as Sunday” on it the rules would control the setpoint as if it was a Sunday (= i’m home the entire day).
I have abandoned all these rules now. The 3 major cellphones in our family are pinged every minute. If at least 1 reports present a dummy presence device called “Anybody home” is set to present. If all 3 phones report absent it is set to absent.
The dummy thermostat is still used, but other rules now change the setpoint. When at least 1 person is at home, the setpoint is set to 20. During the night it is set to 16.5
When nobody is home during the day, it is set to 17. So when we leave the house (going to work / school) the last cell phone leaving the house automatically sets the setpoint back to 17. When someone arrives later in the day it is set to 20 automatically.
When the room temperature drops below the setpoint (minus a margin) and the stove has been OFF for at least 1 hour the stove gets the ON signal. Pimatic is allowed to send a OFF signal only when: temperature (plus) margin is above setpoint for at least 10 minutes and the stove is ON for at least 1 hour.
A rule changes the setpoint from 16.5 to 20 at 05:00 in the morning (IF somebody is at home), thus the stove kicks in a 05:10 every morning. Within the hour the room is warm enough to be comfortable, even when the room temperature had dropped back to 16 degrees.
I have written a program on a ESP8266 to control the stove. Pimatic connects to the HTTP API to tell what to do, the ESP sends the IR signals to the stove.
The stove reports back the state to Pimatic, based on temperature of the exhaust. When the temperature of the exhaust rises with a certain pattern, it reports ‘flame detected’ and tells the stove is on.
So when I manually turn the stove on Pimatic still knows it is already burning.
Anyways … for now everything seems to operate as I intended at the beginning of the project and works without any major problems. Along the way I needed to tweak some stuff but it’s getting better and better.
The margin used to turn of the stove was set to 0.4 degrees. My roomtemperature is measured in steps of 0.25 degrees. So when the setpoint is set to 20, the stove is turned of when room temperature is at least 20.5
It turned out that especially in the morning this was a bit to soon to turn of the stove. The room temperature would drop to rapid below 20 degrees (but the rules prohibit to turn on the stove for the coming hour). I have edited the rules to change the margin to 0.6 when it is between 05:00 and 22:00 when there are is someone at home (so Pimatic will turn of the stove when it is at least 20.75). During the night (or when no one is at home) the margin is set to 0.4
When the dummy thermostat is set to boost the following happens : setpoint stays at current setting, rules do not change the setpoint. When it is to cold, the stove is turned on. As long as the thermostat is set to boost, the stove is not turned off. This allows the stove to control itself based on the room temperature and the setting on the stove itself. I can keep it on boost for the entire day and the stove will automatically shutdown or kick in. With a single button I set the thermostat from boost to auto and everything is back to normal based on presence of family in the house.
I hope somebody finds this information useful on how to monitor and control heating with pimatic with several approaches.
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