### Asset Description:
AHU: Air Handling Unit: A device used to condition and circulate air as part of a heating, ventilating, and air-conditioning (HVAC) system.

### Conditions:
- AHU Running
- Heating AND Preheat AND Reheat Valve % < 5%
- Cooling Valve % < 2%
- (Mixed Air Temperature - Supply Air Temperature) > 7 °F
- 10 °F < OAT < Setpoint Temperature

### How long the conditions were met:
Met for 2 Hours

Given the above detected conditions, what should the operator look for?
A. Flow through valve should be zero
B. Verify pump is not needed and turn off
C. Unit bypassing or blowing off too much air
D. Too much equipment in the local area


# Answer

Answer: A. Flow through valve should be zero

Guidance Rationale: 
 The Air Handling Unit (AHU) is currently running, but all heating, preheat, and
reheat valve positions are below 5%, and the cooling valve is nearly closed
(less than 2%). Despite this, there is a significant temperature drop between
the mixed air and the supply air, with a difference greater than 7 °F,
suggesting unintended cooling or thermal loss. The outdoor air temperature (OAT)
is between 10 °F and the setpoint, meaning outdoor conditions are cool, but not
cold enough to justify aggressive heating. Given that all major valves are
nearly shut and the system is operating in a steady state for 2 hours, the
presence of such a temperature differential raises the possibility of leakage or
unintended flow through one or more valves. 

Therefore, the operator should verify that the flow through the valve is actually zero, to ensure proper
control and avoid unnecessary energy loss. This is the most likely issue
compared to other options: verifying the pump (Option B) is not directly related
to the temperature differential and valve positions; unit bypassing or blowing
off too much air (Option C) would typically result in a temperature rise rather
than a drop; and too much equipment in the local area (Option D) does not
explain the specific valve and temperature conditions observed.