Why crh nrv drains not work perfectly in line?

CRH NRV (Non-Return Valve) drains may not work perfectly in line due to several factors, including improper installation, which can lead to misalignment and ineffective sealing. Additionally, sediment or debris accumulation can obstruct the valve's operation, preventing it from closing properly. Variations in pressure or flow rates can also impact the valve's ability to function as intended. Regular maintenance and proper installation are essential to ensure optimal performance.