Hydronic question but chilled water

SM

If I can figure out how to attach a crude drawing I have several question. We are installing an air compressor in our factory that requires water to cool interstages, oil cooler (shell and tube) and aftercooler all requiring 85 Deg water. Question from drawing will the system as drawn be decoupled if the blue lines are close spaced tee's? There is a modulating valve in the return line to control loop temperature? Current mechanical contractor says that there needs to be a check valve between tee's, is that true? And as for sizing system circulator the pressure of the supply and return to the secondary pumps of the chilled water does not have any effect on the loop for the compressor does it? Isn't this really simular to if not what is discribed as Tertiary bridge design in Bell and Gossett article Applying Variable Volume Pumping - Part II?

EBEBRATT-Ed

IMHO it should work but there may be better ways to do it. I'm just not in favor of two way valves (but am probably out numbered on this) but a few questions. I am assuming that the CW pump (blue piping) is supplying other loads so it will not be dead headed by the two way valve??? Keep the two tees close togeather 6"-12" but don't put one tee on the corner as drawn. I don't see any need for a check valve. Get a copy of Dan's "Primary Secondary Pumping Made Easy" on this website. Money well spent. Has all the info you need and explained much better than I can.

Ed

Tony_8

I think

what you've drawn is correct. I would put the modulating valve in the supply though, with it's sensor in the compressor loop before the loads. The only thing I question is you may need a bypass in the blue loop ahead of the modulating valve so the blue circulator doesn't deadhead. A differential bypass valve probably would be in order. The flow and pressure of the blue pump won't affect the red loop. No check valve is necessary and would serve no purpose.

SM

Many other loads on the chilled water loop. Total system capacity is over 1500 ton, compressor requires about 40 ton. Why not not decouple at the tee on the corner?

Thanks

Doug Wagoner

I agree with

Ed. Do not put the tee on the corner. If your closely spaced tees are placed in the red loop identically there will be no question, the blue loop will be de-coupled.

Tom Blackwell

It deoesn't matter where the tees are; the 40 ton load will not seriously affect the main loop. Most compressors have a control on the oil cooler only, you need to check to see if an additional valve and controller are required. Also check to make sure the pressure rating of the various cooler vessels will not be exceeded by the chilled water system pressure plus the loop pump pressure.

Kal Row

close T rules

- supply rail one pipe size larger than t-offs,
- t-offs closer than 6 supply pipe diameters
- 6 smooth pipe diameters preceding the close-t's on supply for smooth flow

use spring checks on pipes where you dont want heat migration via gravity

http://www.tekmarcontrols.com/acrobat/e022.pdf