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# E+, How to model a AHU double fan (supply air and return air)

In my project, I have an AHU double fan (for air supply and return air) with a heat exchanger and a cooling coil, connected to a VRF. My purpose is to know the cooling capacity inside the room, something like what follow : http://www.daikin.com.sg/product-seri...

I would like to model only the AHU and see the impact of the AHU on my cooling capacity, if is it significant or not.

How can I do this easily in Energy plus ? With "HVACTemplate:Zone:PTAC ? It seems to be quite close of what I would like.
Or with "HVAC templates : zone unitary " ? I have seen in the I/O reference, they model AHU with that one.
By chance, there is an example with AHU ?

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If I understand correctly, which I'm not sure I am, I'd say use an AirLoopHVAC to model the AHU to serve your zone(s) that will provide the fresh air.

The VRF(s) will just condition the zone(s), palce it second in your ZoneHVAC:EquipmentList after the AHU terminal unit, and hardsize the outdoor air flow rate during Cooling/heating/noLoad to zero to ensure it doesn't also bring outside air.

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Thanks for your answer. I try to explain again if is not clear. I have a ahu double fan (supply air and return air) and a cooling coil connected to a vrf. I would like to know How to simulate this in energy plus (thé AHU and thé connection between thé coil and thé vrf). I know How to model a vrf. Its thé others steps that i dont understand

( 2018-09-21 05:21:23 -0500 )edit

You mean your AHU has a VRF coil in it (at the central level)? Does the VRF outdoor unit serve another coil?

( 2018-09-21 07:04:19 -0500 )edit

Yes. The coil of thé ahu is connected to thé vrf. I have one vrf outdoor unit, on one hand connected to some fcu inside unit for AC and on thé other side my vrf is connected to one ahu for fresh air( with a vrf coil). Basically, i would like to model what follow, what they call "vrv ahu system" link text.
Any clue how to model this ?

( 2018-09-21 07:46:34 -0500 )edit

No sorry, I don't see any built in way to do this in E+ unfortunately, at least if said AHU is serving more than one zone (if serving only one, you could just model it like I said above).

( 2018-09-24 09:09:22 -0500 )edit

I am a beginner and I still learning E+. I am little bit lost with all the ventilation subjects in the software. By chance do you have an exemple that I could use ?

On the other side, I did something to simulate my systems, I have used the "HVAC templates VRF zone / system" and the "HVAC templates system : dedicated outdoor air", not sure its correct but can you give me your opinion ? It could be close of what I would like ? Or I am completely wrong ? Thank you for your help

( 2018-09-25 01:41:58 -0500 )edit