Balancing valve in heat exchanger arrangement

[mfqd]

Hi,

Following my previous posts, i would like to ask for another question:

In the image that i attached, there is a balancing valve, that is commonly used. I don't know well why this is used.
For what i undestand, this is used to obtain in this circuit the same pressure drop as the heating device circuit. But, my question is: isn't the 3-way control valve already making that control and compensation?....

thanks

 

[quark]

This is discussed extensively in thread403-239619 I ran systems with and without(inherited) balancing valves but I alwasy prefer them.

 

[mfqd]

Hi,

Sorry, but i didn't attached the image. Here it goes.

Quark,
For what i've seen in that post that you mentioned, the problem is discussed only in relation to 2-way valves.

Whats your opinion in cases like this with 3-way valves?

Thanks

 

[JimCasey]

One function of the balancing valve is that it makes the bypass have the same resistance as the heat transfer coil set.

OR, If the two streams are very different temparatures and the setpoint is near the temp of one of the streams, then an unbalanced loop would be running near one of its extremes of travel. the balancing valve biases the loop so that the control valve operates more toward mid-stroke, in its "sweet spot"

Applies to 2-way valves as well as 3-way valves.

 

[mfqd]

Dear JimCasey,

I understand, but using those same arguments, shouldn't we use also a balancing valve at the HX exit? Because if the flowrate thats passes in the heat exchanger also oscilates, the equipment has different pressure drops, and this should be corrected also, or am i wrong in this thought??....

I didn't understand quite well your 2 santence. Can you please explain it again? Thanks

THANKS