Belimo Energy Valve™ Branch Flow and Delta T Control

Larger buildings have complex distribution systems and are occupied, meaning that the retrofit of an Energy Valve on each terminal is impractical. However, lack of capacity at peak times or fines from district plant providers often drive building owners to look for a solution. The figure below shows a pressure dependent system with a single balancing valve. This is a typical contract installation of multiple low flow heating units, for example, used for underfloor heating.

Our need to operate more efficient buildings, drives the demand to check water flow rates not just once but multiple times during each season. Experience tells us tenant fit outs or changes to hydronic system adversely effect non-PI installations. However, even with PI valves installed, checking the identifying passing valves and open bypasses should remain a priority to keep delta T to an acceptable range.

By using an EV in the branch line, we are able to measure the total flow to the floor and also to each individual unit, if opened sequentially

Ghost energy/passing/leakage is typically used to describe the process where water is unintentionally passing from the flow side to the return. A bypass is left open after maintenance or at axial valve leakage rates. These small rates quickly add up when a large number of them are applied. The rate at which these valves pass or leak is made worse over time by the accumulation of dirt on the seats of the valves.

By using an EV in the branch line, we are able to measure the total flow to the floor and to each individual unit. You can ensure bypasses are closed and valves are not leaking. Should a number of terminal valves suffer from leakage, the characterised ball valve technology in the EV can be closed, hence providing a stop to the wastage when the branch is not in use.

Often, terminal units are statically balanced, which leads them to overflow and deliver low delta T when in part load. Valves may be allowing water past them when they should be closed. Sometimes, even a bypass left open can stay undetected, reducing the pressure and dragging the delta T down.

The Delta T Manager, integrated in the Belimo Energy Valve™, is a function that continuously measures the temperature spread. This information can either be used to raise an alarm while you are troubleshooting the branch, looking for passing/leaking valves or bypasses left open. Once the branch is performing as well as it can, you can enable Delta T Manager to limit overflows to the branch.