Chilled Water Coil

[elmusasc]

1st part
Has any one ever had a chilled water coil that has differant temps througout the coil,, It seems like it has tubes stopped up in it.
2nd part
If my coil is stopped up does anyone have any ideas on how to unstop it

[Argus]

What sort of coil is it?

If it is a shell and tube evaporator where the refrigerant is in the tube and the water surrounds it in the shell, partial freezing up will deform the shape of the tube, sometimes even crushing it in places. This arrangement does not split the tube if it freezes; (the ice tends to crush the tube). This may have happened progressively in the past especially if the water flow rate is low and there is a regular lack of load. I know it shouldn?t happen, but in the real world it often does. If you are really unlucky it may crush the tube where it enters the tube sheet and flood the chiller.


If you can detach the end covers, a visual check can usually determine if the tubes are crushed and how many. If it is too small for this you may have to make a decision to replace the lot.

Depending on the size and make of the evaporator, you may get away with up to 10% of the tubes out of action before there is a lack of performance that cannot be compensated for with water flow adjustments. The manufacturer will advise you about this. In my experience, if it was only a few tubes that were affected, you could plug them off at the tube sheet, with out affecting the performance.
Alternatively, some large evaporators can be re-tubed ? it?s an expensive and a skilled job.
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[slingblade]

If on the other hand if it is chilled water to air hx and partially blocked then try backflushing it or running an acidic cleaner or descaler through. it may possibly just need bleeding.

[jamcool]

Can I also add:o ,If Its a chill water coil as in a AHU unit u can also do a water pressure check (inlet reading,outlet reading) If a big pressure drop at outlet and flow rate drops then as u said coil might be blocked.
How to clear,counterflow or backwash the coil(use the inlet as the outlet and use the outlet as the inlet).:confused: If that works then u might want to think about strainers on your inlet to catch any stuff in the future and also look into your chill water treatment system if rust inhibitor is being used(if the blockage is rust).

[jamcool]

Slingblade got here before me so,DITTO:) :D