2-Way VS 3-Way Valve: Which Is the Better Option?

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2-Way VS 3-Way Valve: Which Is the Better Option?

2-Way VS 3-Way Valve: Which Is the Better Option?

Characteristics of 2-Way Valves and 3-Way Valves

A 2-way valve is any type of valve with two ports: an inlet and an outlet port, typically labelled A and AB respectively. With two ports, the valve passes the water in one direction only.

3-way valves have three ports, labelled A, B, and AB. With three ports, the 3-way valve passes the water in two directions.

These are two criteria to determine if you need a 2-way valve or a 3-way valve: water flow, and the type of valve operation you require.

Water Flow

Use a 2-way valve in a system with a variable water flow that experiences changes in flow, pressure, and temperature. 2-way valves allow operators to run heating and cooling systems at variable flow rates, increasing process efficiencies, and lowering their operating costs.

The 3-way valve is used in a system with constant water flow.

Valve Operation

2-way valves only have a simple On/Off operation. They can immediately stop fluid flow to a specific location and are essential components in many process safety systems.

3-way valves have two different operations: They can be used as mixing valves or diverting valves.

When used as a mixing valve, fluids of varying temperatures and pressures from ports A and B are mixed inside the valve body. The mixed fluid is transmitted out of port AB.

​When used as a diverting valve, the fluid can either flow from AB to B and vice versa, or AB to A and vice versa. The 3-way valves have an L-shaped or T-shaped bore, which affect the circuit function (flow direction). This can be seen in Figure 3. As a result, various circuit functions can be achieved such as distributing or mixing flows.



Figure 3: Example of a 3-way ball valve and the circuit functions for a T-bore and L-bore.

Advantages and Disadvantages of 2-Way and 3-Way Valves

Each type of valve has its pros and cons. The table below highlights the key advantages and disadvantages of 2-way valves and 3-way valves.
Advantages Disadvantages
2-way valves 2-way valves
1. Cheaper to buy and install 1. Most chillers and some boilers cannot handle widely varying flow rates
2. Variable flow which reduces pumping energy and piping heat losses 2. Differential pressures increase across control valves, reducing system controllability
3. Reduced or eliminated system balancing 3. Can only be used for 1 purpose
4. Potentially lower costs for pumping and distribution systems  
3-way valves 3-way valves
1. More cost-effective for diverting and mixing applications than using multiple 2-way valves 1. If used for mixing purposes, a 3-way valve can only be used at low differential pressures
2. Can be used for 2 purposes: mixing or diverting fluids  

​ Lian Ee Hydraulics has been finding innovative answers to some of the world’s most challenging hydraulic connections for the past 30 years. We provide reliable 2-way and 3-way valves that are suited to all your needs. View them here.