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Heat Pump in AHU with Geothermal

asked 2017-05-24 17:35:29 -0500

BL's avatar

updated 2017-05-25 18:03:36 -0500

I need to model a HP in AHU with water source geothermal as a heat sink. However, in OS the WSHP is only available in zone terminal units, not in central AHU. Any suggestions how to model that ?

Update:b I am thinking about a work around that set up two separate chilled water and hot water loop with vertical bore field or plant load profile. Any comments ? image description

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@Julien Marrec do you have any idea ? thanks

BL's avatar BL  ( 2017-05-25 08:03:46 -0500 )edit

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answered 2017-05-25 18:03:04 -0500

You're on the right track, but you should use a single ground source loop where the ground source heat exchanger is on the supply side, and then both the AHU cooling and heating coils are on the demand side (see below).

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You will just need to be sure to apply the proper setpoint manager objects to achieve the desired outlet temperature (read more here). I'll point out here that using the ground source heat exchanger objects requires lots of inputs for the bore holes and other data that is best obtained from a ground source system design tool like GLHEPro. Unless you already have this info, you can create a preliminary system using district heating and cooling objects on the supply side (see below) to generate ground source condenser loop capacities, then use that info to size the ground source heat exchangers. For more info, check out this tutorial and this question.

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@Aaron Boranian Aaron, thank you so much !!!!!

BL's avatar BL  ( 2017-05-26 11:08:42 -0500 )edit

@Aaron Boranian Hi Aaron, I found an issue that if I set the design loop exit temperature to 90 or higher, the sizing of cooling coil fails. I hard size the cfm and water flow of CC, it seems like providing no cooling. Any suggestions ?

BL's avatar BL  ( 2017-05-30 09:57:05 -0500 )edit

@Bo_Lin Step #4 in the referenced tutorial at the end of my answer post discusses the sizing options to use. Set "Loop Type" to "Condenser" instead of "Heating" or "Cooling", set "Design Loop Exit Temperature" to desired max GSHX water temp, etc.

Aaron Boranian's avatar Aaron Boranian  ( 2017-05-30 11:41:04 -0500 )edit

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Asked: 2017-05-24 17:35:29 -0500

Seen: 645 times

Last updated: May 25 '17