HVAC equipment and BMS role

[saeedplc]

Dear Experts

I have great experience of working on the plc. systems and different machines but not on HVAC system too much
As far as I know HVAC equipments such as chillers ,Air handling units and boilers have their own controller
that control function of them but I am curious to know how is BMS related to these functions so I
would be appreciated to guide me regarding the below questions:

What parameters should be monitored on the BMS system?(set points? status? or etc.)
How much authorization should BMS system have on the equipment in aspect of control?
Does boilers or chiller should be staged according to temperature or flow demanded from the load side?

If you have a sample or worked project I would be appreciated to let me have it for further information or any
good books that you have found useful according to your experience

Regards,

 

[EnergyProfessional]

it depends a lot on what the manufacturer provides...


Modern boilers have their own control for staging etc. the BAS just gives a temperature setpoint, and the boiler control decides how many boilers to turn on and how to modulate etc. Boilers also often control their own isolation valve. We often read out data via points or BACnet. So for example, I can read the firing rate, but I don't control it directly.
it also depends a lot on how comfortable you are with the manufacturer and how sophisticated they are. You also need to separately control minimum flow, for example. So it all depends...... In the old days we had BAS do the boiler staging, now we let the boiler controller do that.

 

[saeedplc]

Thanks a lot for your reply,

Is there any good book regarding this subject or any project documents to get familiar with control methods and etc.?

 

[EnergyProfessional]

You really have to know what the device offers. They also have options to get more data out of them, but they cost extra. So it depends on what the owner wants to pay for and also what the designer knows or feels comfortable with.