[Equest-users] Air-source and ground-source heat pump modelling

[Nicholas Caton]

eQuest can explicitly model VRF with heat recovery, ground source well fields (with either water to water or water to air heatpumps), hydronic heating via natural gas boilers and the state of no cooling... so all of your bases are covered with respect to the platform.  DOE2.3 notably offers a great deal more detail and confidence with respect to modeling VRF systems using a component-based model, with the provided library curves being relatively manufacturer agnostic and applicable to various VRF system configurations.

As for "any ideas..." well you'll need to compose some more specific questions to get specific answers.  I'd encourage you to first explore the wizard-level and detailed mode input options available for the listed systems, review the associated reference manual help entries wherever something is unintuitive (generally, right click an input field and use the context menu to help you navigate to the related entry / section of the help files), and then let us know if you are struggling to understand or implement something specific.

Something you haven't defined here but will become pertinent to understand before you finish an accurate projection is how specifically you intend to retain/ sequence the existing hydronic heating boilers/coils/fans as a "backup" or supplementary heating source.  Of what you posed so far this sounds like the potentially 'trickiest' piece of the simulation puzzle.

Also, you haven't revealed your climate but if there is no mechanical cooling to start, I anticipate you'll also want to define for yourself early on exactly how you intend to utilize the VRF and existing hydronic heating in relation to the mechanical ventilation, economizer functionality, and the heat recovery bits.  You might for example decide to lock out the VRF system below a certain exterior temperature setpoint and switch over to only hydronic heating, which may in kind preclude the option to recover heat off the makeup airstream depending on how you're physically providing for that function.

~Nick

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Nick Caton, P.E., BEMP
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From: Equest-users <equest-users-bounces at lists.onebuilding.org> On Behalf Of Inga Goebel via Equest-users
Sent: Monday, November 4, 2019 2:18 PM
To: 'equest-users at lists.onebuilding.org' <equest-users at lists.onebuilding.org>
Subject: [Equest-users] Air-source and ground-source heat pump modelling


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Hello,

I am trying to model an air-source heat pump in eQuest in order to redesign the HVAC system in a 1980s commercial building. Currently there are three natural gas fired boilers who provide the heat throughout the building and no air conditioning present. Air conditioning is to be added and the system to be made more energy efficient. I am looking at an air source heat pump from Mitsubishi (City Multi model) and would like to model it in eQuest to see how this changes the energy consumption of the building. I am struggling with how to model it in eQuest though.  It is an outdoor VRF heat pump with a heat recovery system.  As a backup heating system I would like to keep the boilers. Any suggestions on how I could implement that the best?

Also, as an alternative I would like to compare it to a ground source heat pump. No specific model chosen yet, just curious to see how it performs compared to the air source heat pump. Any ideas on how to model this as well?

Thanks,

Inga


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