[BLDG-SIM] Trouble with Heat Pumps (eQuest)
Xiaobing Liu
XLiu at climatemaster.com
Wed Aug 15 14:54:52 PDT 2007
Brandon:
As promised, I post following instruction for obtaining the heat pump library.
The heat pump library and other associated files for eQUEST to access the library are packaged in a self-extracted zip file, which can be downloaded at <http://www.climatemaster.com/index/equest> http://www.climatemaster.com/index/equest after proper registration. In addition to the heat pump library, the standard release of eQUEST 3.6 and an eQUEST training handout focused on the enhanced GSHP simulation and the heat pump library can also to downloaded. In order to access the heat pump library directly from eQUEST wizard, the self-extracted zip file has to be unzipped over the installation of eQUEST. The instruction for unzipping the file is shown in the above web page. The procedure for selecting a heat pump from the library is described in slides 77-84 of the training handout.
As an add-on feature, the heat pump library can be accessed by eQUEST starting from version 3.6.
When you register, please make sure mentioning "RE: [BLDG-SIM] Trouble with Heat Pumps (eQuest)" in the text box for comment. Since the downloading request is still handled manually, it may take a few days for us to verify your registration and send you a link for downloading.
Hope it could be a small help for your simulation.
Xiaobing
-----Original Message-----
From: BLDG-SIM at gard.com [mailto:BLDG-SIM at gard.com]On Behalf Of Brandon Nichols
Sent: Tuesday, August 07, 2007 5:51 PM
To: BLDG-SIM at gard.com
Subject: [BLDG-SIM] Trouble with Heat Pumps (eQuest)
Xiaobing,
Many of us I think would be interested in the heat pump library. How can it be accessed?
Thanks
Brandon Nichols, PE
Mechanical
HARGIS ENGINEERS
600 Stewart Street
Suite 1000
Seattle, WA 98101
www.hargis.biz
d | 206.436.0400 c | 206.228.8707
o | 206.448.3376 f | 206.448.4450
_____
From: BLDG-SIM at gard.com [mailto:BLDG-SIM at gard.com] On Behalf Of Xiaobing Liu
Sent: Monday, August 06, 2007 2:40 PM
To: BLDG-SIM at gard.com
Subject: [BLDG-SIM] Trouble with Heat Pumps (eQuest)
Karen:
If you create a heat pump system using eQUEST wizard, in the first screen of the wizard system (after you specifying both cooling and heating equipment as "DX Coil"), an additional input entry will appear and ask you specify the source of the heat pump. The available options include "Air", "Water Loop", and "Ground Loop". When "Water Loop" is selected, the HVAC system will be defined a water loop heat pump (WLHP) system (with boiler and cooling tower); When "Ground Loop" is selected, the HVAC system will be defined as a ground source heat pump (GSHP) system that uses water-to-air heat pumps connected to a common (water) loop and a vertical borehole field as heat sink and source.
I'm not clear why you have to deal with HIR for WLHP and GSHP systems since these heat pumps are electric-driven. I guess you were talking about the EIR instead of HIR.
The PVVT is used to simulate the air side of a water-to-air heat pump so that it can account for the recent developments of water-to-air heat pump, such as the usage of staged compressor, variable speed fan, etc. If the WLHP/GSHP is created with the eQUEST wizard, parameters associated with the PVVT system will be automatically set for constant air flow, and default WLHP/GSHP heat pump performance curves will be used. The default curves are normalized at the ARI rating conditions for "ground loop" application (77F EFT for cooling and 32F EFT for heating). If the WSHP/GSHP is created in detailed mode, at this version of eQUEST, the user has to adjust the parameters of PVVT to fit for the specific heat pumps being simulated. I've listed some necessary adjustments for the parameters of PVVT in my earlier post to the topic "Gshp in detailed edit mode".
FYI, a performance data/curve library for all the water-to-air heat pumps of a major water-source heat pump manufacturer has been built and, as an add-on feature of eQUEST, it can be accessed directly from the wizard of "Packaged Equipment" if either WLHP or GSHP is specified. Please let me know if you are interested in the library and this add-on feature.
Hope it helps in your simulation.
Xiaobing
-----Original Message-----
From: BLDG-SIM at gard.com [mailto:BLDG-SIM at gard.com]On Behalf Of Karen Walkerman
Sent: Monday, August 06, 2007 2:57 PM
To: BLDG-SIM at gard.com
Cc: BLDG-SIM at gard.com
Subject: [BLDG-SIM] Trouble with Heat Pumps (eQuest)
Thanks for all the responses. I think I figured it out:
When you choose "WLHP" in the eQuest Wizard, it creates a PVVT system with a GSHP. The curve used to adjust HIR is based on a few data points, and did not perform very well at the temperatures I was using. A straight HP system selected in detailed edit mode did much better. I now realize that this is because the HIR curve was better for my purposes. I have now created curves based on the heat pumps spec'd for this job and the numbers are making more sense.
Thanks again for all the repsonses, thought I'd let everyone know, especially because PVVT is what is selected when you create a WLHP system with the wizard, and may need some detailed data edit tweaking.
~Karen~
On 8/6/07, Brandon Nichols < BrandonN at hargis.biz> wrote:
Hello Karen,
"When so many things can go wrong, almost certainly more than one of them will go wrong at the same time" ... or something like that, according to Murphy. Recently I have been wrestling with a large heat pump system, and may be able to help a little.
Have you adjusted your heat pomp efficiencies? Ground and water source heat pumps will have different efficiencies, if for no other reason than they are operating with different condenser water temperatures.
Check this post...
http://elcca-exchange.blogspot.com/2007/03/ground-water-source-heat-pumps.html
Next suspect, schedules... don't have a post for that yet, let me know the effect of efficiency adjustments and we'll go from there.
Regards
Brandon Nichols, PE
Mechanical
HARGIS ENGINEERS
600 Stewart Street
Suite 1000
Seattle, WA 98101
www.hargis.biz <http://www.hargis.biz/>
d | 206.436.0400 c | 206.228.8707
o | 206.448.3376 f | 206.448.4450
_____
From: BLDG-SIM at gard.com [mailto: <mailto:BLDG-SIM at gard.com> BLDG-SIM at gard.com] On Behalf Of Karen Walkerman
Sent: Friday, August 03, 2007 5:20 PM
To: BLDG-SIM at gard.com
Subject: [BLDG-SIM] Trouble with Heat Pumps (eQuest)
I apologize for all the emails I've sent out as of late. Thanks for all the input.
I have another:
I'm comparing a ground source heat pump to a heat pump loop with chiller and boiler. Trouble is, when I switch systems, the energy used by the heat pump to heat the space goes down only slightly as compared to the energy input by the boiler. My loop temperatures change between the systems (from heating temp of 40 F to 70 F), and COP rises accordingly. Right now the energy use of the two systems is off by about 85%!!
Energy use for straight electric resistance heat is about the same as the electric use for a heat pump system. This is for a baseline model with 18% evenly distributed windows, R-19 batt insulation, R-38 ceilings, etc.
I used the wizard to set up the equipment for all runs (I'm also having trouble in detailed edit mode). The water loop and the heat pump don't seem to be talking to one another. Can anyone help?
Thanks,
--
Karen Walkerman
Second Law Consulting
802-238-0980
kwalkerman at gmail.com <mailto:kwalkerman at gmail.com>
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Karen Walkerman
Second Law Consulting
802-238-0980
kwalkerman at gmail.com
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