PICV 2

[Manu68]

Hi Experts,

PICV as the brochure is a combination of flow control that works to deliver the required chill water flow irrespective of upstream pressure pressure in the pipe line. When that is the case I believe there is no need to have double regulating valve or other control valves. As the AHU load decreases PICV closes irrespective of the upstream pressure in the chilled water pipe line. Similarly when pressure is high in the up stream pipe but AHU load is low PICV closes. Could you please throw light from your experience.

 

[EnergyProfessional]

timothy: it is a control valve as well... the actuator modulates it. Obviously this needs to be controlled by BAS via AHU DAT. Follow the Honeywell link above and see an example.

 

[Timothi]

Hi HerrKaLeun,

Thank you very much for the reply. Pl correct me if I'm wrong.

When the load in the AHU is less, the return water temp is also less than designed CHWR temperature which is sensed by the temp sensor located in the AHU return pipe. What does this sensor do? Send signal to BAS or directly communicating with the PICV?

Thanks in advance

 

[EnergyProfessional]

under normal (partial) load the temps always will be different than at design conditions. The return water sensor isn't used for control, it isn't really necessary since the DAT tells you if you have water flow or not (no flow, no change in DAT).

Discharge Air Temperature is compared to the set value. If DAT is too high, the cooling coil valve opens up. If it is too low, the valve closes. There also is a PID loop to control that etc... that is what the controller does.