Model 800X

Coliter ® Differential Pressure Bypass Balance Valve – PN16, ≤120°C, Hydraulic Self-Control for Constant ΔP in Water Systems

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800X
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800X Differential Pressure Bypass Balance Valve – Pilot-Operated Automatic Bypass Valve to Stabilize Pressure Difference in HVAC & Municipal Networks

The Coliter® 800X Differential Pressure Bypass Balance Valve is a self-operated hydraulic control valve that automatically maintains a preset pressure difference (ΔP) between the supply and return lines of closed-loop water systems. It is widely deployed in high-rise buildings, residential complexes, district heating/cooling networks, and urban water supply projects to ensure stable operation under variable flow conditions, prevent coil overflow, reduce pump energy consumption, and eliminate noise caused by pressure surges. The valve integrates a main valve, a differential pressure pilot valve, needle valve, ball valve, micro filter, and pressure gauges into a single hydraulic control system. When the actual ΔP exceeds the setpoint, the pilot valve opens to drain the control chamber of the main valve, causing it to open and divert excess flow—thereby reducing the differential pressure back to the target value. This negative feedback mechanism operates entirely on system hydraulics, requiring no external power, electricity, or instrumentation. Constructed from ductile iron or cast steel, rated at PN16 (1.6 MPa), and suitable for media temperatures up to 120°C, the 800X complies with relevant Chinese standards and is available in sizes from DN50 to DN400 with flanged end connections per GB/T 17241.6. By dynamically balancing system pressure, the 800X enhances comfort, improves energy efficiency, and simplifies commissioning in modern hydronic infrastructure.

Installation diagram

Product Description

DNLHH1DD1Z-Φd
1.0MPa1.6MPa2.5MPa1.0MPa1.6MPa2.5MPa1.0MPa1.6MPa2.5MPa
20150212179---------
25160212179---------
321802121791401401401001001004-184-184-18
402002652101501501501501101104-184-184-18
50203/2302652101651651651651251254-184-184-18
65216/2903102151851851851451451454-184-188-18
80241/3103502452002002001601601608-188-188-18
100292/3504603052202202351801801908-188-1888-23
125330/4005203652502502702102102208-188-188-25
150356/4805704152852853002402402508-188-188-25
200495/6006955103403403602952953108-2312-2312-25
250622/73078056039540542535035537012-2312-2512-30
300698/85090565844546048540041043012-2312-2516-30
350787/980102569650552055046047049016-2316-3016-34
400914/1100108073556558062051552555016-2316-3020-36
450978/1200103061061564067056558560020-2520-3020-36
5001075/1250113566567071573062065066020-2520-34-
6001100/1450127072578084084572577077020-3020-41-
7001448146086589591096084084087524-3024-41-
8001956164097010151025108595095099024-3424-41-

The 800X differential pressure bypass balance valve is composed of a main valve, a differential pressure control pilot valve, a needle valve, a ball valve, a micro filter and a pressure gauge to form a hydraulic control takeover system. Through the specially designed pilot valve control room, the pressure change signal is compared, the main valve opening signal is output, and the main valve opening is controlled to control the inlet and outlet pressure difference of the main valve at the set value. The working principle is that when the pressure difference between the inlet and outlet of the main valve changes, the pressure difference between the takeover A and the takeover B changes, and the opening degree of the variable pilot valve. When the pressure difference is large, the pilot valve opening is large, the discharge volume of the control room through the C pipe increases, the pressure in the main valve control room decreases, the opening degree of the main valve increases, and the pressure difference between the inlet and outlet of the main valve becomes smaller. Conversely, if the pressure difference between the inlet and outlet of the main valve becomes smaller, then the pilot valve opening becomes smaller, the pressure in the control chamber of the main valve rises, pushing the opening of the main valve to decrease and increasing the pressure difference of the main valve. This negative feedback effect makes the pressure difference between the inlet and outlet of the main valve stable at the set value. The needle valve opening and pilot valve spring pressure can be set to set the pressure difference between the main valve inlet and outlet. This product uses hydraulic self-control, does not require other devices and energy, and is easy to maintain. It is widely used in high-rise buildings, living areas and other water supply network systems and urban water supply projects.

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Faq - Frequent questions

Coliter®’s differential control valves automatically maintain stable pressure differentials in heating, cooling, and variable-flow HVAC systems to ensure balanced operation and protect equipment. The series includes the ZYC self-operated differential pressure control valve, which uses system pressure feedback to modulate flow without external power, and the 800X differential pressure bypass balance valve, which diverts excess flow between supply and return lines when ΔP exceeds setpoint. Constructed from high-quality brass or cast iron, these valves are rated at PN16 (1.6 MPa) and suitable for temperatures up to 120°C. They enable energy-efficient pump operation, prevent coil overflow, and eliminate noise—ideal for chiller plants, underfloor heating manifolds, and district energy networks.