Control Valves on the Supply or Return Chill Water System? 1

[thien2002]

My drawing indicates the Honeywell 3-way modulating Control Valves on the Supply side (modulating the return side), shouldn't the Valve be on the Return Side for Chiller Water and Hot Water System? I thought it was a drawing error. Would that effect the flow efficiency if it's located on the wrong side?

Thank you in advance.

 

[jmw]

My usual concern with coolant water flow is if the medium being cooled is or can be above 100degC. In which case i don't want a fully closed valve on the discharge side trying to contain a build up of steam. It may depend if there are any safety valves in the design.
Let's see what the experts say.

 

[pardal]

Plaese check what kind of valeve it is ,
Diverting valve on the supply side.

Mixturing vale an the return side .




Pardal

 

[pardal]

Plaese check what kind of valeve it is ,
Diverting valve on the supply side.

Mixturing valve an the return side .




Pardal

 

[quark]

Pardal is right. A mixing valve is always installed on the return line and a diverting valve on the supply line. Though both installations are technically correct, it is better to use mixing valves(on return line). The advantages are that, you can always ensure your coil is totally filled and also as the return temperature is higher you will have less problems with valve body sweating.

Regards,


Eng-Tips.com : Solving your problems before you get them.

 

[thien2002]

Please explain:
"A mixing valve is always installed on the return line and a diverting valve on the supply line. Though both installations are technically correct, it is better to use mixing valves(on return line)."
** Please define mixing or diverting.
"The advantages are that, you can always ensure your coil is totally filled and also as the return temperature is higher you will have less problems with valve body sweating."
** What happen if valve body sweating, what consequences?

THANK YOU

 

[pardal]

Talking about fluid, it is hard to divert or divede than to mix.
And the diverting valve is more expensive than mixing.

I dissagree about sweating , the return water will be always under the dewpoint of air , so it will allways sweat.

When instaling you shall locate the actuator preferible on top or by the sides , never on the bottom , because sweat water will damage the actuator.







Pardal

 

[quark]

Mixing Valve - Which mixes two streams into one stream.
Diverting Valve - Which diverts one stream flow into two stream flow.

The links below will give you good understanding and selection procedures.

http://www.spartan-pd.com/PDFfiles/Piping.pdf

http://www.belimo.com/IMS_DOCS/56/56189BE43C17984A862A4EC1B1999C9D.pdf

http://www.belimo.com/IMS_DOCS/21/21BD69054E68674C8BA60E4D1417EAB8.pdf

Disadvantages with sweating.

1. Energy Loss (latent heat from condensing moisture is transferred to chilled water) - Superfluous
2. May corrode your system slowly - Most Likely
3. May cost your job - If you are in a Pharma Company
4. You may have to arrange for floor cleaning frequently - Obvious

Pardal!

I agree with your disagreement (huh... so kind of me). I said that the sweating problems will be less and not that they will be eliminated.

Regards,


Eng-Tips.com : Solving your problems before you get them.

 

[pardal]

Quark. If two do not want , one do not can.



Pardal

 

[ercanbaser]

I think , statement "A mixing valve is always installed on the return line and a diverting valve on the supply line" is not 'always' correct because there are applications which mixing valves used in supply line and diverting valve used in return line as can be seen at links quark's post.

first,proportional control valves should not be mixed with 2-position "3-way valve" , secondly the control logic must be considered (constant flow or cnst.temperature)and pressure drop for both sides of 3-way valve should be calculated to ensure the valve work properly. (if it is not equally ballanced valve may be %50 open but fluid flows ,lets say, %40 because it 'always' prefers the easiest way).Pump location should also be considered.

I hope , I dont 'mix' too much

Ercan