This leaking preheat valve case is unique. It is a rare issue due to the site location and the conditions under which it occurred, and it took time and collaboration to solve. It required both data analysis and field investigation to identify the fault and determine the root cause. 

Analytika uncovered an AHU preheat valve that leaked only when the humidifier was running. What would cause those two pieces of equipment to interact? The usual suspects were BAS point configuration or sequence of operations errors. However, a thorough review of the BAS found the configuration was fool-proof. The next step was to go into the field and recreate the conditions in which the leakage occurs. Sure enough, the heating valve was observed opening when the humidifier was running. Further field investigation revealed the missing link between the preheat and the humidifier – they shared a pneumatic line.

Have you solved the mystery?

Due to a leak in the pneumatic air system, there was not enough pressure in the loop to keep both the normally open heating valve closed and the normally closed humidifier valve open. The humidifier valve was upstream of the heating valve in the pneumatic line. When the humidifier was required, there was not enough pressure to keep the normally-open heating valve closed.

Before and after Leaking Preheat Valve

The leaking preheat valve was not detected on site by building operators because the AHU met setpoint. In addition, due to the infrequent occurrence of preheating and humidification given the warm-weather location of the site, it was not detected by traditional commissioning methods.

Cimetrics directed facilities personnel to the symptoms and conditions that result in the leaking preheat valve, worked with facilities to identify the root cause, and confirmed the fix after the repair of the pneumatic system. Data confirms that the preheat valve no longer leaks when the humidifier is required.

Annual energy savings achieved: $3,500

The annual savings for this issue are relatively small because the specific set of conditions that caused the fault are infrequent, but these savings are persistent year after year now that the root cause was fixed.

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