Hydronic distribution for HVAC-systems are too often settled with an outdated technological approach, making the overall system inefficient and distributing more water than is necessary. Big savings can be made in terms of energy consumption by changing the distribution system.
Over the years, the solutions to generate heat and cold in HVAC systems have been fine-tuned and optimized, making the most out of technical advancements in the field.
Particularly in Europe, the Ecodesign regulatory framework has introduced a specific focus on the seasonal efficiencies of the unit, thus considering that in a real building the machines work for most of their time in partial load conditions.
This has led to a paradigm shift in the units design with the optimization of the efficiency of the units in partial load operation compared to full load. This optimization was achieved with the introduction of variable speed components (primarily fans and compressors).
Over the next few years, heat and cold generation will become more efficient than ever, consuming less electricity and making a smaller impact on the climate.
An outdated technological approach
However, the hydronic distribution systems are still often settled with an outdated technological approach, making the overall system less than optimized. Water pumps used to transfer heat and cold within a plant, are often over-dimensioned as well as designed to only run at full capacity, with a fixed water flow no matter the real demand of the plant. It is like running a train with always the maximum number of cars, no matter the real number of passengers. No reason to keep moving such a big amount of water. In particular, primary and secondary hydronic systems are often designed for peak conditions only, but the reality is that they will run at part load most of the time, wasting both energy and money. To properly optimize the system as a whole, the hydronic system needs to be rethought.
Energy savings can be made
The simplest way to make it more efficient reducing energy consumption is to add an inverter to the primary water pump that will match the exact water flow required by the nominal design of the plant without the use of an inefficient balancing valve.
To optimize the system even further, you need a smart integrated system that can sense the actual demand and adjust both generation and distribution. Adding temperature and pressure sensors makes it possible to analyze the real-time capacity demand of the system and adjust the water flow accordingly, for an even more efficient operation.
The biggest savings will be achieved if you remove the secondary system altogether and use only a primary system for distribution of heat and cold. A variable flow primary pumping system is most easily planned for and installed in new buildings, and it results in a highly efficient distribution system that is up to par with the rest of the plant. This can save up to 55 percent of pump electricity consumption, reducing the overall system energy needs by 15 percent.
It makes no sense to install the most efficient up-to-date heat pump unit and pair it with an old fashioned water distribution system. Modernizing the distribution system with a variable flow system should be a given. It makes no sense not to do it.