Over the years, I’ve had a lot of questions asking if I prefer to operate zoned hydronic systems based on a set temperature drop between supply and return water temperature (e.g., ∆T control), or a set pressure drop across the distribution system (e.g., ∆P control).
Both methods of speed control attempt to better match the flow rate in the system with the current heating requirements of the building. The ultimate goal is to reduce electrical energy use without compromising comfort.