Monitoring Boiler Flow Temperature
Overview
I have a basic gas boiler in a conventional setup. After watching Heat Geek channel and their videos on heat pumps, I too wanted to look at how efficient my boiler was running.
I did not want to make permanent changes to my boiler or plumbing because I do not have the skill set to do so. This means it may not be the most accurate way of monitoring but hopefully it will be better than nothing. The boiler is less than 3 years old at this stage so replacing the boiler does not make financial sense.
Hardware
Optionally, clamps for 22mm pipe. Due to the heat, I’d recommend non PLA such as PETG or ABS to withstand the temperature and structural rigidity.
Wiring
The DS18B20 thermometer uses 1 wire protocol. As long as each thermometer has a different address then they can all communicate using one data wire connected in a series. The live and neutral are fairly self explanatory and can use either 3.3 or 5v from the Wemo d1 Mini.
I also created an extra sensor to calculate the delta (difference in temperature) between the outgoing and incoming water (flow and return).
ESPHome
ESPHome supports the sensor so follow the instructions here. The “hardest” part was getting the ID’s of the probe.
Example configuration can be found here.
Once configured and adopted, the sensors will be presented as device and entities for use in Home Assistant.
Example configuration can be found here.
Data & Insights
The goal is to get the greatest temperature difference (Delta T) between the outgoing heated water (flow) and the water coming back (return). The higher the difference, the more heat loss and therefore more heat has gone from the water into the house.
At 70% it the temperature difference was about 4 degrees Celsius.
Changing this to approximately at 40% gave the same results ignoring the initial warming cycle yields similar results so in theory, setting it to a lower power will be more efficient because it’s not running at higher power and use less gas. This will be very hard to validate without a temperature controlled room / house.
Summary
A fairly easy to follow video by Tom McGuinness describes some of the shortfalls in this setup.
Retrofit options will never be as accurate as built in so my next step is to try and get an EMS gateway to access the boiler data direct.
