2-way valves are pretty simple and straight-forward. A 2-way valve is any type of valve with two ports: an inlet and an outlet port, typically labeled “A” and “AB” respectively. 2-way valves are used in many applications, from basic on/off to more complex variable flow applications with pumps and VFDs. The type of valve you need for an application depends on the amount of flow, the degree of control, shut-off, and pressure drops over the valve.
3-way valves have, yes, three ports, labeled “A”, “B”, and “AB”. Port “AB” is common to the “A” or “B” port. 3-way valves are commonly found in constant flow/volume pumping systems and can be either mixing or diverting valves. 3-way valves can be piped in the supply or return. If in the supply, then a diverting valve is used. If piped in the return, a mixing valve is used. Ball valves can be piped to be mixing or diverting, but globe valves require different bodies for mixing or diverting.
Mixing applications have the 3-way valve configured with two inputs from the supply piping and one output to the return piping, thus mixing together two inputs before sending it out. Mixing valves are most commonly used with modulating control but can be on/off.
Diverting applications have the 3-way valve configured with one input from the supply side and two outputs to the return piping. In general, diverting valves are more expensive than mixing valves.
Make sure to watch this short easy to understand video on control signals .
Every valve has some sort of control actuator and control signal. It could be on/off, floating, or a proportional signal. Click here and watch this easy to follow, short, HVAC Tech School video and learn the easy way about HVAC control signals.
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13 Responses
Superior internet site. Thank you!,
Thank you !
where and why do we neeed to use 2 and 3 way valves in chilled water circulation. please send a rough sketch with explaination.
Very nice write-up. I definitely love this site. Continue the good work!
Hello.This post was extremely interesting, especially since I was browsing for thoughts on this matter last
couple of days.
kljo Delta
Can you use a 3way valve as a two way if you cap the a port or will this cause damage over time
A no nonsense; straight to the point explanation on differences between a 2 -way valve and a 3-way valve. Credits to having this important nugget of information avail on site!
There are a lot of options available in the market, so why would one choose ZFA valves over everyone else? Because ZFA valves are top-tier industrial valve manufacturers. Not only that, there are a few more points to that. One is that the engineers who build these valves are precise and efficient. The second is the heck load of customizable options. The third and probably the most important one is that strict quality control and regulation over the staff.