Chiller water information

[ronsin1]

Hi all,
can anyone help
We have an air cooler chiller with a closed looped system wtih chill water pumps and 4- 40 ton air handler units.

I have having some heat exchange problems That I cannot seem to solve.

I have water leaving at 45 degrees and returning at 48 to 50 degrees.

I have sox ducts on the AHU which tend to drop I have done a full coil cleaning and can say the coil is clear and air passes through. I cannot remmeber the CFM of the unit at the momnet but last it was checked it was with in range.

[Gary]

Why do you think its a heat exchange problem?

For that matter, what makes you think there is a problem?

[Tesla]

We need more info to help on this one like - air on, air off, supply outlet temp, chwv position and chwbypass position. Is it a VAV or FAV?

[nike123]

I have water leaving at 45 degrees and returning at 48 to 50 degrees.

I have sox ducts on the AHU which tend to drop

Did I correctly understood that you have flexible (textile) ducts from air handling units which "tend to drop"? What this "tend to drop" mean?
Check fans rotation direction and proper air flow!

[ronsin1]

Did I correctly understood that you have flexible (textile) ducts from air handling units which "tend to drop"? What this "tend to drop" mean?
Check fans rotation direction and proper air flow!

all the system I deal with are fabric duct systems. The unit that is in question use to have the ducts firm. now they are not firm as they use to be.

The fan rotation is correct I have check that already it moves in a clock wise direction as how it always is

Gary it has to be a heat exchange problem on the evaporator coil. I have a good water supply temp.

with this temp I should have an ambient temp inside the building of 71F but I o not have that I have more like 79 which is to high.

I have another building with the same system an do not have these issues

[Gary]

What controls the temps?

Is the AHU multizone or single zone?

Face/bypass air dampers?

Chill water bypass?

What are the water pressures?

What is the system elevation?

We need to know more about the AHU.

[nike123]

all the system I deal with are fabric duct systems. The unit that is in question use to have the ducts firm. now they are not firm as they use to be.



To me that indicate that air flow across unit is less than before. Less air flow mean less heat gain at AHU and therefore delta T of water at evaporator is smaller and capacity of unit is lowered.
Measure your airflow. Check with manufacturer data for proper airflow.
If fan motors are mono-phase, check capacitors for correct capacity.