Predheat weather comp (#1752)

* Add weather_compensation

* Remove weather_comp_max

* [pre-commit.ci lite] apply automatic fixes

* Remove testing constant and tidyup

* [pre-commit.ci lite] apply automatic fixes

* Add weather comp documentation

* Correct weather comp doc

---------

Co-authored-by: pre-commit-ci-lite[bot] <117423508+pre-commit-ci-lite[bot]@users.noreply.github.com>

apps/predbat/predheat.py

@@ -115,6 +115,8 @@ def __init__(self, base):
         self.heat_pump_efficiency = HEAT_PUMP_EFFICIENCY.copy()
         self.gas_efficiency = GAS_EFFICIENCY.copy()
         self.delta_correction = DELTA_CORRECTION.copy()
+        self.weather_compensation = {}
+        self.weather_compensation_enabled = False
 
         # Collect predheat settings
         heat_pump_efficiency = self.get_arg("heat_pump_efficiency", {}, domain="predheat")
@@ -129,17 +131,27 @@ def __init__(self, base):
         for key, value in delta_correction.items():
             self.delta_correction[key] = value
 
+        weather_compensation = self.get_arg("weather_compensation", {}, domain="predheat")
+        if weather_compensation:
+            for key, value in weather_compensation.items():
+                self.weather_compensation[key] = value
+            self.weather_compensation_enabled = True
+
         # Fill gaps in tables
         self.delta_correction = self.fill_table_gaps(self.delta_correction)
         self.gas_efficiency = self.fill_table_gaps(self.gas_efficiency)
         self.heat_pump_efficiency = self.fill_table_gaps(self.heat_pump_efficiency)
+        self.weather_compensation = self.fill_table_gaps(self.weather_compensation)
 
         self.heat_pump_efficiency_max = max(self.heat_pump_efficiency.values())
         self.log("Predheat: Delta correction {}".format(self.delta_correction))
         self.log("Predheat: Gas boiler efficiency {}".format(self.gas_efficiency))
         self.log("Predheat: Heat pump efficiency {}".format(self.heat_pump_efficiency))
         self.log("Predheat: Heat pump efficiency max {}".format(self.heat_pump_efficiency_max))
 
+        if self.weather_compensation_enabled:
+            self.log("Predheat: Weather compensation {}".format(self.weather_compensation))
+
     def minutes_to_time(self, updated, now):
         """
         Compute the number of minutes between a time (now) and the updated time
@@ -352,8 +364,15 @@ def run_simulation(self, volume_temp, heating_active, save="best", last_predict_
             heat_power_in = 0
             heat_power_out = 0
             if heating_on:
+                out_temp = int(external_temp + 0.5)
+                out_temp = min(max(out_temp, -20), 20)
                 heat_to = target_temp
-                flow_temp = self.flow_temp
+
+                if self.weather_compensation_enabled:
+                    flow_temp = self.weather_compensation.get(out_temp)
+                else:
+                    flow_temp = self.flow_temp
+
                 if volume_temp < flow_temp:
                     flow_temp_diff = min(flow_temp - volume_temp, self.flow_difference_target)
                     power_percent = flow_temp_diff / self.flow_difference_target
@@ -371,8 +390,7 @@ def run_simulation(self, volume_temp, heating_active, save="best", last_predict_
                     heat_power_in = heat_power_out / (condensing * self.heat_cop)
                 else:
                     # Heat pump efficiency based on outdoor temp
-                    out_temp = int(external_temp + 0.5)
-                    out_temp = min(max(out_temp, -20), 20)
+
                     cop_adjust = self.heat_pump_efficiency.get(out_temp, self.heat_pump_efficiency_max) / self.heat_pump_efficiency_max
                     heat_power_in = heat_power_out / (self.heat_cop * cop_adjust)
 

docs/predheat.md

@@ -121,3 +121,16 @@ The final figure should be the number of watts your house loses per 1 degree of
 
 Then you can set **heat_gain_static** to be the static heat output of other things in your house eg. computers and people. You can figure this out by looking at how many degrees of
 temperature difference your house can maintain without any heating and multiply up your heat loss watts figure by this.
+
+### Weather Compensation
+
+If your heat source makes use of weather compensation then add the following to the configuration to map out your heat curve. The example has a flow temp of 45C at -3C outside and 25C at 15C outside:
+
+```yaml   weather_compensation:
+      -20: 45.0
+      -3: 45.0
+      15: 25.0
+      20: 25.0
+```
+
+Predheat will fill in the gaps between the points provided.