emoncms.org• Apr 16, 2024• 1 min read
Efficient gas boiler with real-time dataI would like to share with you the real time performance of my condensing gas boiler, managed by SAT and OpenTherm.Many gas boilers are oversized which means it's more difficult to run them efficiently. Also, many gas boilers have capability to run more efficiently but are not configured to.This particular boiler does not seem to respect the MM=0 command (despite OpenTherm's such specification requirement) which is not uncommon. SAT sends the MM=0 command for the boiler to work at its minimum capacity. CS= minimum_setpoint and then PWM controls the ON/OFF times of the boiler. However, I have a workaround which ensures that most of the time, the boiler is indeed working at its minimum modulation, unless the target flow (heating curve + PID) demand is high [higher than current flow temperature] during warm up.The boiler supplies heat to the central heating and domestic hot water tank, but not at the same time. The hot water tank capacity is 255 litres. When DHW call is made, boiler ignor