Construction Inspection
Collect the pump curve submittal and note the impeller size. This establishes the curve that the pump should be operating on. It is not uncommon to find that a pump shipped with a different impeller even though the correct impeller is indicated on the plate of the pump.
•Ensure all valve and piping arrangements were installed per the design drawings in order to achieve the desired control. This refers to each heat exchanger or coil having its own two-way control valve, flow measuring devices, if applicable, are located adequately to achieve accurate measurements (i.e. sufficient straight-line piping before and after the meter), and the piping arrangements are correct (for example there may be three-way valves located at one or more of the coils to ensure system minimum flow rates can be achieved).
Functional Testing
Step 1: Deadhead One Pump.
The intent of this test is to establish a baseline pump pressure for use in checking the ability of all valves to close across the system. Use manual isolation or balance valves at the inlet or bypass of all three way valves and close it off. If a balance valve is used mark its current position so that it can be reset after the test.
Verify and Document: Isolate one circulation pump and make sure that all chillers or boilers are off. Close off the isolation valve at the pumps discharge and turn the pump on for not more than 5 minutes. Measure and note the pressure across the pump at this “deadhead” condition. If the system is piped primary/secondary make sure this is a secondary pump. At the end of the measurement turn off the pump and open the discharge valve at the pump.
Step 2: Close control valves.
The intent of this test is to ensure that all two-way valves can modulate fully closed and have actuators that can fully close across an operating pump. With the chillers or boiler still off, start the same pump that was used in Step 1 and drive all HX or coil control valves closed. Closing the control valves can be achieved in a variety of ways, examples of which include: resetting control setpoints so that valves respond accordingly; commanding the valves directly using the DDC control system (i.e., building automation system); or applying a fixed amount of air pressure to an actuator or valve in the case of a pneumatic control system. Make sure that the pump operates for no more than 5 minutes in this “deadhead” condition.
Verify and Document:
Ensure each control valve closes completely under normal operating pressure. The intent is to make sure that the actuator-valve torque requirements are adequate to shut the valve under normal operating system pressure. Verifying complete closure shall be done by measuring the pressure across the operating pump. If the pressure is more than 5% less than that previously measured the test fails as one or more valves have not fully closed. Diagnose and fix the problem then retest.
Step 3: Return system back to normal operating condition.
Ensure all schedules, setpoints, isolation and balance valves, operating conditions, and control parameters are placed back at their initial conditions.