When is too much water no good?

            We deal in water every day when we deal with hydronic heating, but can there be too much water moving through the piping? Well, sometimes, and when that happens, the velocity noise can be unbearable. This becomes even more prevalent if zone valves are present.

I know many installation companies use zone valves, mainly due to cost, and if installed correctly they do a fine job. However, if they are not installed correctly, you and I are the ones who have to resolve the problem or the customer has to learn to live with the noise of water rushing through the piping.

            Now, all zone valves are not created equal, as you can imagine.  Taco and Honeywell are the ones I most found in the field, but there are other manufacturers coming out with their own versions. All of them have one thing in common’they all rate the valves in Cv ratings. 

Did you ever take this rating into consideration when installing or replacing a zone valve?  Are you asking yourself what is a Cv rating?  O.K. well I just happened to pull this description from Wikipedia: 

            The flow coefficient of a device is a relative measure of its efficiency at allowing fluid flow. It describes the relationship between the pressure drop across an orifice, valve or other assembly and the corresponding flow rate.”  Mathematically the flow coefficient can be expressed as:  Cv = F ‘ SG/’P where:
            Cv = Flow coefficient or flow capacity rating of valve.
            F = Rate of flow (US gallons per minute).
            SG = Specific gravity of fluid (Water = 1).