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Member Post to Member Post
👉@Member Post kuhn Asked
“First time diving inside this type of issue and looking for some advice.
I have an AHU with water coils that is having issues holding supply temp setpoint. It’s all over the map. Supply setpoint is @ 55 degrees but it’s modulate the chilled water and hot water actuators trying to hold it. It’ll get as high as 65 and low as 50. Constant roller coaster.
I started leaning towards issues at the AHU and not with the chiller. (Chiller has 12 AHUs and only one is havin this issue, the others are good). Gone through and verified controls are not the issue, actuators are not sticking, and CHW setpoint is being met.
I am starting to lean towards a partially plugged coil. At the coil, I have the following:
-Supply water pressure: Bouncing 62-68 psig
-Return water pressure: Steady at 50 psi.
I attached a gauge to the vent line to measure pressure at the top of the coil and it’s holding steady at 62 psig. Opened the vent but theres no air. Cleaned coil and verified airflow is good (VFD driven)
I’m leaning towards a partial restriction inside the coil. Are there other ways to verify this? I found the as build specs and it calls for a pressure drop that equates to just shy of 2 psig. Am I missing something? Going down the wrong path? And insight would be appreciated.
Edit: Customer does water treatment. Coils have never been rodded or cleaned.”
