[Equest-users] Question about air-cooled heat pump

Nicholas Caton ncaton at catonenergy.com
Wed Dec 2 22:12:05 PST 2015

Hello Hang Cui,

>From your choice of words, I think you intended to include the eQuest-users
mailing list and so I am CC’ing in response as this may help others.  The
files you sent are fine for reviewing the question at-hand, but be aware
you may want to attach your weather file as well if you should later need
help concerning specific simulation outputs/results.

The system diagram and description below is helpful.  You may have
correctly identified a difference in common terminology between our
languages.  Rather than simply “Air-cooled heat pump,” which represents a
rather broad category of equipment/system configurations, and referencing
your illustration, I might more specifically describe your intended system
as a “2-pipe fancoil system with air-source heat pumps on heating/cooling
water loop.”  This presumes the same loop is used for heating or cooling
(but never both simultaneously).

If that description seems accurate, I would concede that I’m not aware of a
2-pipe configuration system option currently included in the wizards
(perhaps someone else in the list can chime in here?), but there is some
direct guidance for this system type in the help files.

Referencing your file I would first explore setting your chillers to be of
type ‘Heat Pump’ (HEAT-PUMP) and to change your primary CHW loop servicing
the terminal fancoils to be of type ‘2-Pipe’ (‘PIPE2’).

I would then review this article and its children in the DOE-2 help
files:  *Volume
2: Dictionary
> HVAC Components
> Air-to-Water Heat-Pump (HEAT-PUMP, AIR-COOLED)*

Also consider the DOE-2 help entries concerning 2-pipe loops and airside FC
2-pipe system operations to ensure you do not miss any of the associated
inputs required, particularly the loop operation inputs which determine on
what conditions the loop will change between heating and cooling
operation.  A conversation with your system/controls engineer(s) (if that
is not already you) may prove helpful on this point.

I would also advise 2-pipe systems by their nature have potential for
“expected unmet hours” when you have zones that require heating and cooling
at the same time served by a common loop and for a period when the loop
must “switch modes” during swing seasons.  Be mindful of that nature and
give consideration to whether it will make sense to remove certain zone
thermostats from the simulation (or else evaluate what an acceptable range
of coincident unmet hours must be with all conditioned zones reporting).

I confess that while I have related design/specification experience for
residential and small commercial cases, I haven’t performed a 2-pipe system
energy analysis in recent memory, so I’m probably missing some details –
keep your eyes and mind open as you proceed!



*Caton Energy Consulting*
  306 N Ferrel

  Olathe, KS  66061

  office:  785.410.3317


*From:* Hang Cui [mailto:bj_hangcui at sina.com]
*Sent:* Wednesday, December 02, 2015 10:35 PM
*To:* 'Nicholas Caton'
*Subject:* 答复: [Equest-users] Question about air-cooled heat pump

Thanks for Nick.

I am not sure if this is the right way to send my project to you all. I
attach my .inp and .pd2 file in this mail. Please let me know if you can
see that.

According to Nick's description, do you mean that it might have chance to
set an air-cooled heat pump by adjusting the inp file of a wizard-generated
DX system project? To my knowledge, DX system can be used to simulate a VRV
system that the refrigerant will flow between the fan-coil in the room and
the primary equipment outdoor. However, what I need is an air-cooled heat
pump that the refrigerant will flow only in the primary equipment and the
chilled or hot water will flow in the fan-coil for cooling or heating the
room. Since I am not sure if my expression is clear (sorry , my pool
language skill), I attach two figures for your convenience.

Looking forward your reply.



[image: 2013510165753581]

*Hang Cui*

*China Construction Engineering Design Grounp Co., Ltd.*

Building 15, Sanlihe Road

Beijing, 100000
e-mail: bj_hangcui at sina.com


*发件人**:* Nicholas Caton [mailto:ncaton at catonenergy.com
<ncaton at catonenergy.com>]
*发送时间:* 2015年12月3日 8:14
*收件人:* Jones, Christopher; 崔航; equest-users at lists.onebuilding.org
*主题:* RE: [Equest-users] Question about air-cooled heat pump

Agreed, it would help solve the issue to see the project at-hand.

That said, you *should* be able to generate a variety of air-cooled
heatpump system configuratinos using the DD wizards.  It might prove
helpful to quickly create a separate simple project in that manner,
befitting your actual system, to compare wizard-generated inputs against
your current project.


*Caton Energy Consulting*
  306 N Ferrel

  Olathe, KS  66061

  office:  785.410.3317


*From:* Equest-users [mailto:equest-users-bounces at lists.onebuilding.org] *On
Behalf Of *Jones, Christopher
*Sent:* Friday, November 27, 2015 7:10 AM
*To:* 崔航; equest-users at lists.onebuilding.org
*Subject:* Re: [Equest-users] Question about air-cooled heat pump

I suggest posting your .inp and .pd2 file to the egroup. Someone will look
at it to determine what might be incorrect.

[image: cid:image003.png at 01D09C46.E75BA0D0]

*Christopher Jones,* P.Eng.
Senior Engineer

*WSP Canada Inc.*

2300 Yonge Street, Suite 2300

Toronto, ON M4P 1E4
T +1 416-644-4226

F +1 416-487-9766

C +1 416-697-0056


*From:* Equest-users [mailto:equest-users-bounces at lists.onebuilding.org
<equest-users-bounces at lists.onebuilding.org>] *On Behalf Of *??
*Sent:* Friday, November 27, 2015 1:54 AM
*To:* equest-users at lists.onebuilding.org
*Subject:* [Equest-users] Question about air-cooled heat pump

Dear eQuest users

Recently, I got a problem when I try to simulate an air-cooled heat pump.
Since we cannot choose air-cooled heat pump under wizard mode, I try to set
it under detailed mode. What I have done:

1. Switch the default 'chilled water loop' to '2-pipe loop';

2. Switch the chiller type to 'heat pump';

3. Switch the HW loop to 'chilled water loop' in air-side system;

However, when I try to switch the condenser type to 'air cooled', an error
is shown like 'assigned symbol air-cooled is of an incompatible type'. Does
anyone be confused by this situation? I guess someone may have solution for


Hang Cui

e-mail: bj_hangcui at sina.com

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