Treading lightly with your involvement in troubleshooting in new construction commissioning is necessary to avoid busting your budget or having others shift their responsibility onto you.
Ideally, recommendations for addressing complex issues will prompt healthy collaboration between team members who all keep an open mind and remain committed to doing the right thing for the building.
I've found if your recommendation includes challenging the Big Mistake often seen with a demand-controlled ventilation (DCV) sequence for air-handing units (AHUs), you better be prepared for some unexpected arguments.
Demand Controlled Ventilation (DCV) is a control strategy which aims to vary the amount of ventilation air a system provides a space based on the real-time ventilation requirements (i.e. the ventilation demand) of the space.
Bypass pipes, accompanied by a three-way control valve, are often seen in hydronic systems at both served loads (e.g., reheat coils) as well as at primary equipment (e.g., cooling towers).
These six case studies, covering just the last three years, illustrate how bad second-order effects can get when there are problems with the bypass pipe’s balancing valve.