Question-and-Answer Resource for the Building Energy Modeling Community
Get s tarted with the Help page
Ask Your Question
5

What is the best layout for supply equipment setpoints: after equipment or after mixer?

asked 2016-06-14 15:02:48 -0500

DW gravatar image

I have a condenser loop that has both a boiler and a cooling tower on it. This condenser plant loop serves both zonal water-to-air heat pumps and water-to-water heat pumps that are connected to radiant loops. I have seen some on this site suggesting that the proper equipment layout should be in series and that setpoints should be placed after each piece of equipment.

Initially, I modeled my loop this way, but the simulation resulted in an enormous EUI of 530 kBtu/ft2!!

image description

I then removed the setpoints after each individual piece of equipment and kept only the dual-setpoint manager after the mixer.

image description

This new arrangement with only the dual-setpoint manager resulted in the much more reasonable EUI of 64 kBtu/ft2.

My question is which setpoint layout is correct? I was using only scheduled setpoint managers and a dual setpoint manager - is there a more appropriate selection for the condenser loop or is there some other control that I'm not implementing correctly in OS?

For reference, my scheduled setpoint after the boiler is 150 F, my scheduled setpoint after the cooling tower is 45F, and my loop dual setpoint is set to a range of 60F - 100F.

Any advice would be appreciated.

edit retag flag offensive close merge delete

1 Answer

Sort by ยป oldest newest most voted
1

answered 2016-06-15 04:11:40 -0500

Chandan Sharma gravatar image

EnergyPlus example file 5ZoneWLHPPlantLoopTower.idf models similar configuration with boiler and tower in parallel configuration. SetpointManager:Scheduled:DualSetpoint can be used at plant supply outlet node (i.e. after mixer) to specify high/low temperature setpoints. Plant Loop Demand Calculation Scheme should be set to DualSetpointDeadband. Engineering reference has more information on working of DualSetpointDeadBand scheme.

edit flag offensive delete link more

Your Answer

Please start posting anonymously - your entry will be published after you log in or create a new account.

Add Answer

 

Question Tools

2 followers

Stats

Asked: 2016-06-14 15:02:48 -0500

Seen: 167 times

Last updated: Jun 15 '16