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Is it possible to model a two-speed fan in energyplus? I can see only on-off and VAV fan objects. I am modelling a residential two-stage unitary-system where at low loads the compressor and fan is at 70% and cycling and at high loads, the fan and compressor is at 100%. I think I need a 2-speed fan for this, but if there is some other way to model the system, would appreciate it if some one can point it out. Thanks, -Rohini

Is it possible to model a two-speed fan in energyplus? I can see only on-off and VAV fan objects. I am modelling a residential two-stage unitary-system where at low loads the compressor and fan is at 70% and cycling and at high loads, the fan and compressor is at 100%. I think I need a 2-speed fan for this, but if there is some other way to model the system, would appreciate it if some one can point it out. Thanks, -Rohini-Rohini Update: I finally got back to this. Based on the comments (I tried all, other than EMS), it looks like the fan does not cycle. Here are the results - The RTF is varying between 1-0.56. The supply temp is varying between 14-20C. The supply flow/RTF comes to the 100% value. The st1 speed is 64% of st2. The unitary system control Is based on Load, the fan type is OnOff. So looks like the flow is not varying at all and only temp is varying. If I look at the times when the RTF is 1 – the supply temp is still varying between 14-20C – in reality the supply temp should be near 14C, and the RTF would be less than 1.The same coil (curve for 100%) used as single speed works as expected – the temp varies slightly between 12C-13C, the flow/RTF is constant at the max value. Is there anyway to vary the flow to the st1 cfm or st2 cfm using a two-speed coil? Thanks.

Is it possible to model a two-speed fan in energyplus? EnergyPlus? I can see only on-off and VAV fan objects. I am modelling a residential two-stage unitary-system where at low loads the compressor and fan is at 70% and cycling and at high loads, the fan and compressor is at 100%. I think I need a 2-speed fan for this, but if there is some other way to model the system, would appreciate it if some one someone can point it out. Thanks, -Rohini Update: out.

Update: I finally got back to this. Based on the comments (I tried all, other than EMS), it looks like the fan does not cycle. Here are the results - results:

• The RTF is varying between 1-0.56. The supply temp is varying between 14-20C. 1-0.56.
• The supply temp is varying between 14-20C.
• The supply flow/RTF comes to the 100% value. value.
• The st1 speed is 64% of st2. st2.
• The unitary system control Is based on Load, the fan type is OnOff. OnOff.

So looks like the flow is not varying at all and only temp is varying. If I look at the times when the RTF is 1 – the supply temp is still varying between 14-20C – in reality the supply temp should be near 14C, and the RTF would be less than 1.The same coil (curve for 100%) used as single speed works as expected – the temp varies slightly between 12C-13C, the flow/RTF is constant at the max value. value.

Is there anyway to vary the flow to the st1 cfm or st2 cfm using a two-speed coil? Thanks.coil?