In heating and air conditioning systems, uneven temperature distribution is a common issue. Some users experience temperatures that deviate from the standard due to hydraulic imbalance—essentially, an unreasonable flow distribution of hot water across different zones. To address this, balancing valves are typically used. Traditional heating systems operate on a uniform heating model, which involves constant flow adjustments based on qualitative assessments. The Jincheng heat network follows this approach, with self-regulating flow balance valves installed at all user entrances. However, this method has encountered several challenges in practice.
For example, valves produced by Linfen Huasong Valve Co., Ltd.—such as self-flow balance valves and self-pressure control valves—have specific working principles and applications. A self-operated flow balance valve functions by adjusting the flow rate based on pressure differences. When the pressure difference (P2 - P3) exceeds a set value, the valve automatically closes to maintain the desired flow. Conversely, if the pressure difference drops below the threshold, the valve opens again. This ensures consistent flow despite fluctuations in system conditions.
However, these valves have limitations. They require a minimum operating pressure of 20 kPa, and when installed in the most unfavorable parts of the system, they may demand higher circulation pump lift, which increases energy consumption. In the Jincheng system, improper installation locations have led to inefficiencies. For instance, installing flow balance valves near the return pipe can cause underpressure in certain areas, while placing them too far from the heat source may reduce their effectiveness. Proper placement should consider building height and distance from the heat source: low-rise buildings benefit from installation on the supply line, while high-rise buildings should use the return line to prevent air locking.
Additionally, in large heating networks with significant pressure differences between supply and return, it’s important to install flow balance valves strategically. Manual balancing valves can be used alongside them to fine-tune pressure levels, ensuring a stable flow throughout the system. Recent trends show that Jincheng's heating system uses frequency converters to adjust pump speed based on outdoor temperature, leading to variable flow operation. However, this can cause imbalance, as self-regulating flow valves may not adapt well to changing flows. In such cases, manual valves are more effective for achieving proper hydraulic balance.
Another key component is the self-acting pressure control valve, which differs from flow balance valves in its function. While flow valves regulate flow, pressure control valves manage the pressure differential across the user system. They respond to changes in network pressure or internal resistance, maintaining a constant pressure difference. This makes them ideal for systems where user demand fluctuates, supporting active variable flow operations.
The installation of pressure control valves can vary depending on the system layout. They can be placed on either the supply or return line, with different structures for each. Installation methods include at the main entrance of buildings, individual units, or even per floor. Each method has its own cost and efficiency considerations, with the first option being the most economical.
Overall, the use of self-acting pressure control valves offers better flexibility and stability compared to traditional flow balance valves, especially in modern heating systems that prioritize user-driven variable flow. As metering reforms continue, integrating pressure controllers into user systems helps avoid complications during future upgrades, ensuring smoother and more efficient heating performance.
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