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How to add a preheat coil before heat exchanger?

asked 2023-05-10 05:39:44 -0500

updated 2023-05-10 10:32:09 -0500

I am trying to set up an air loop with two coils between the outdoor air node and the inlet to the heat exchanger, as shown in the image below.

image description

Can I add coils before the OAM or does it need outdoor air?

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answered 2023-05-10 10:28:16 -0500

Keigo's avatar

You can add coils before OAM (OutdoorAir:Mixer). You can refer to the ExampleFile: TermRhGenericOAHeatRecPreheat.idf in your PC.

The order of componets in the ExampleFile is

(Outdoor air) -> Preheat coil -> HEX -> OAM -> Fan -> Cooling coil

The preheat coil and the HEX are listed in AirLoopHVAC:OutdoorAirSystem:EquipmentList.

    OA Sys 1 Equipment,      !- Name
    Coil:Heating:Electric,   !- Component 1 Object Type
    Outdoor Air Preheat Coil,!- Component 1 Name
    HeatExchanger:AirToAir:SensibleAndLatent,  !- Component 2 Object Type
    OA Heat Recovery 1,      !- Component 2 Name
    OutdoorAir:Mixer,        !- Component 3 Object Type
    OA Mixing Box 1;         !- Component 3 Name

The fan and the cooling coil are listed in Branch.

    Air Loop Main Branch,    !- Name
    ,                        !- Pressure Drop Curve Name
    AirLoopHVAC:OutdoorAirSystem,  !- Component 1 Object Type
    OA Sys 1,                !- Component 1 Name
    Air Loop Inlet Node,     !- Component 1 Inlet Node Name
    Mixed Air Node,          !- Component 1 Outlet Node Name
    Fan:ConstantVolume,      !- Component 2 Object Type
    Supply Fan 1,            !- Component 2 Name
    Mixed Air Node,          !- Component 2 Inlet Node Name
    Cooling Coil Air Inlet Node,  !- Component 2 Outlet Node Name
    Coil:Cooling:Water:DetailedGeometry,  !- Component 3 Object Type
    Detailed Cooling Coil,   !- Component 3 Name
    Cooling Coil Air Inlet Node,  !- Component 3 Inlet Node Name
    Air Loop Outlet Node;    !- Component 3 Outlet Node Name
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Thank you, I didn't realise I could include the coil in the OutdoorAirSystem object.

FinMilliner's avatar FinMilliner  ( 2023-05-11 09:58:13 -0500 )edit

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Asked: 2023-05-10 05:39:44 -0500

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Last updated: May 11