The relevance of traditional Commissioning Set Valves in Building Services
9 April
HVAC installations have to be balanced to ensure the correct flow to all parts of the system, ultimately resulting in occupant comfort and energy/cost efficiency.
While in modern heating and cooling systems Pressure Independent Control Valves and Pressure Dependent ΔT Valves have largely replaced traditional Commissioning Set Valves, Differential Pressure Control Valves and Actuated Control Valves, there are still many applications for Commissioning Set Valves in HVAC.
Applications
Balancing valves are required when water needs to be proportionally balanced.
- Within a traditional constant flow system or building extension. A typical terminal unit arrangement.
- Within PICV-controlled zones. A PICV-controlled zone commissioning set valve installation.
The conventional Commissioning Set Valve market in the UK is highly competitive with no clear market leader or product differentiation. However, there are trends and some product variations worth considering.
Venturi versus Fixed Orifice Double Regulating Valve (FODRV)
A venturi is a device for measuring flow either integrated into the commissioning valve or used independently. The benefits of the venturi include:
- A significant proportion of the pressure loss is recovered after flow has passed through it.
- High pressure and energy recovery make the venturi suitable in systems where only low differential pressures are available.
- Flow can be measured to within ±3% across the entire range, compared to the normal ±5%.
- The venturi measuring orifice accelerates water flow, increasing the measured signal, ensuring the significant pressure loss common in other valve systems is recovered as it passes through. Energy is therefore not needlessly expended in pressure recovery, which makes these valves highly efficient.
- Returns a higher and cleaner signal (typically 10 to 30 kPa, depending on flow rate) without the pressure loss, making for simpler and easier commissioning.
- No straight lengths of pipe are required either upstream or downstream of the measuring orifice (except immediately after a pump, which cause water turbulence). This can be a considerable advantage in a tight plant room and offers a more elegant method of commissioning for modern buildings. Source: MBS Magazine
Globe-Style versus Butterfly & Orifice Plate Commissioning Sets
- The Butterfly & Orifice Plate Commissioning Set is suitable for small spaces, when weight is a concern, when budget restrictions apply or for DN300 + line sizes when the Globe-Style is not available. It can be delivered pre-set to site.
- The Butterfly & Orifice Plate Commissioning Set is typically available up to DN800, and some suppliers can supply up to DN1400 on request. The weight of the Butterfly & Orifice Plate Commissioning Set is approximately 1/3 of the weight of a traditional Globe-Style valve.
- The Butterfly & Orifice Plate Commissioning Set is not only lighter and smaller and therefore easier to handle and install, it is also available in large sizes and provides an opportunity for significant cost savings.
FAQS
What is a commissioning set in HVAC?
A commissioning set in HVAC refers to a combination of valves and measuring devices used to balance and test water flow throughout the system. It ensures that all components receive the correct flow rate for efficient operation and occupant comfort.
What does a commissioning valve do?
A commissioning valve is designed to control, measure, and regulate water flow within a hydronic system. These commissioning valves are key during flow commissioning, ensuring that each section of the system is balanced according to design specifications.
How does a commissioning valve work?
Wondering how a commissioning valve works? It allows engineers to measure differential pressure and calculate the actual flow rate using built-in test points. This makes pressure commissioning more accurate and simplifies the system’s balancing process.
When should you use a commissioning set valve?
A commissioning set valve is used when setting up or retrofitting constant flow systems or PICV-controlled zones. These commissioning valve sets help stabilise flow across all terminal units, preventing overflows or under-delivery in complex building layouts.
What’s the difference between commissioning valves and control valves?
While commissioning valves help measure and balance flow, control valves adjust flow dynamically based on demand. Together, they ensure efficient water distribution and are often used in tandem during flow commissioning and system fine-tuning.
Is flow commissioning necessary in all HVAC installations?
Yes, flow commissioning is vital in both traditional and modern HVAC systems. It ensures consistent water delivery and helps maintain system pressure. Skipping pressure commissioning can lead to performance issues and energy wastage.
Can a PICV symbol be found in every schematic?
The PICV symbol represents a Pressure Independent Control Valve. It’s frequently used in modern HVAC schematics where commissioning valves are used alongside PICVs for accurate balancing in variable flow systems.
What are the advantages of commissioning valve sets with a venturi?
A commissioning valve set with a venturi provides higher accuracy, minimal pressure loss, and doesn’t require straight pipe lengths. This makes it a top choice for tight plant rooms and ideal for pressure commissioning in compact installations.
How is pressure commissioning conducted?
Pressure commissioning is performed by setting up commissioning valves at specific locations and measuring the pressure drop across them. This data helps determine if water is flowing at the desired rate, ensuring system balance.
What’s the role of commissioning sets in modern vs. legacy HVAC systems?
In legacy systems, commissioning sets play a critical role in manual balancing. While modern systems use PICVs more frequently, commissioning set valves are still essential in certain applications like retrofits or where flow commissioning precision is required.
