Balancing Valve vs. Ball Valve

Peter_26

<span style="font-size:12pt">I've noticed that in a lot of manufacturer installation instructions they refer to a ball valve as a way to throttle the flow. From all the research I've been doing it has been stated that a ball valve will wear with time and you will lose the ability to control the flow properly and that is why balancing valves are preferable. Is it ok to use a ball valve in some situations to control flow or is it a must to use a balancing valve? </span>

djthx

Flow control valves.

Globe valves are used for flow control; Ball valves are meant for isolation (shutoffs).

Peter_26

Not disputing with that fact...

Thanks for the reply, but I understand that heating systems need shut off valves, but I am strictly referring to ball valves being used for controlling flow.

EricAune

A guess at best

True throttling is done with measurement.  That being said, just using a ball valve without any way to gauge the difference from one side to another would be a guess at best. 



Globe valves, venturi's and circuit setters are the best bet for altering flow without introducing less desirable conditions like turbulence and noise. 

Peter_26

Sounds very logical

I have even read about gauges being used to compare supply and return temperatures, but again using ball valves to control flow. The other factors you mentioned are something to worry about too. I'm guessing that it's an economical alternative to a balancing valve, but at the cost of reliability in the long run. Is that correct?

Jean-David Beyer

Valves in manifolds...

Note that I am not a contractor.



The supply manifold for my hydronic heating system has ball valves in it. I have one zone upstairs (2 rooms in series with finned-tube baseboard emitters) with no manifold, and one zone downstairs (5 rooms with the supply to each room going through a ball valve). The boiler has outdoor reset.



 It seems to me that whatever the merits of one valve type over another, this is a problematic way to adjust the relative heat delivered to the different rooms on one zone, even though that is what I have.



One trouble, at least in theory, is that ball valves do not have a nice control over the flow. Most of the range affects the flow relatively little, and when the valve is almost closed, it is difficult to make fine adjustments. Furthermore, if you run flow through such a valve in the almost closed position, the ball can wear out prematurely. That would never have occurred to me (as a non-professional), but I read it in John Siegenthaler's book, and assume he is right.



The second trouble, it seems to me, is that lowering the flow in the slab for a particular room does not make exciting changes in the delivery of heat to a room unless the flow is greatly reduced. It seems it would cool off the room only if you could get the delta-T high enough, and in my case, the delta-T is pretty low, like 4F or so (depends a lot on outside temperature). I know that for the Slant/Fin baseboard I have upstairs, the BTU/hr/ft number goes up only a little as the flow rate goes from 1 gpm up to 4 gpm.



So what I did was to turn all the valves full on, and then lower them a bit at a time to the rooms that were too hot. Now one thing I did not want to do is turn one all the way off, because it would be likely to freeze. It currently runs with 3 valves full on, one partly on, and one closed so much you can hear (if you listen carefully) the water going through the almost-closed ball valve. I do not know the flow rates, and I guess I do not care.





If I really cared, I suppose I might have installed zone valves down there and a thermostat in each room. However, it seems to work well enough now, except for the possible early failure of the almost-closed ball valve.

Big Ed_4

Valves

Globe valves and ball valves are both listed and throttle valves ...