[Equest-users] No Heating from PVVT Heat Pump

[Bishop, Bill]

Eddie,
You can see with your attached model that at least you are getting
heating and the system is operating. To get rid of your unmet hours, you
will have to refine the model. First put the accurate loads and envelope
in (including getting rid of the exterior floor I mentioned previously)
and make sure your schedules (lighting, equipment, occupancy etc.) are
reasonable. Then change some interior walls to air walls as applicable
(interior walls that aren't actually there, such as corridors that open
into a space without a door) to more evenly distribute loads within each
floor. Finally, add system capacities and zonal air flows. Perimeter
baseboard heating may be needed in the design if the windows and walls
are as poor as your previous attached model suggests. You might also
create a custom capacity curve (HEAT-CAP-FT) for the Mitsubishi heat
pump.
Regards,
Bill
 
William Bishop, PE, BEMP, LEED(r) AP | Pathfinder Engineers & Architects
LLP
Mechanical Engineer
 
134 South Fitzhugh Street
Rochester, NY 14608
T: (585) 325-6004 Ext. 114
F: (585) 325-6005
wbishop at pathfinder-ea.com
www.pathfinder-ea.com
P   Sustainability - the forest AND the trees. P
 
________________________________

From: equest-users-bounces at lists.onebuilding.org
[mailto:equest-users-bounces at lists.onebuilding.org] On Behalf Of Eddie
Corwin
Sent: Wednesday, September 29, 2010 2:15 PM
To: equest-users at lists.onebuilding.org
Subject: Re: [Equest-users] No Heating from PVVT Heat Pump
 
Bill and Kelly, thank you for your input.
 
Bill:
I have tried using the wizard to create the PVVT heat pump.  I even used
"system per zone" so that each zone is controlled independently.  Even
coming strait out of the wizard, there are plenty of heating hours not
met.  I understand that a stand air-to-air heat pump will be unable to
operate in very cold weather, but that is where the supplemental heat
should take over to get rid of any unmet hours.  I have attached this
model.
 
The actual system I am trying to model is the Mitsubishi Hyper Heating
Inverter Y-Series Heat Pump.    This system (in heating mode) uses
electric resistance heat to warm the outdoor air before it reaches the
outdoor coils.  This ensures that heat transfer will occur between the
OA and the outdoor coil, and allows for operation at temperatures as low
as -13*F.  At first I thought that eQuest can not exactly model a system
like this, so maybe eQuest is not allowing any heat transfer between the
cold coil and the cold air.  But then I tried again using the RESVVT,
and it seems to work well, even in the middle of winter.  My only
objection to using the RESVVT is that I would like to have control over
the OA.
 
Kelly:
 
You say that I can not use PVVT with an air cooled compressor, but it
says that it is possible in the DOE2 help file, also, the wizard will
set it up that way.  Normally I would just use the PSZ or even PTAC to
model an air-to-air heat pump, but I would like to use the variable
speed compressor, so I need to use a VVT system.
 
 
Has anyone modeled an air-to-air HP system that operates at such low
temperatures before?
 
Thanks,
 
-Eddie
 
 
 
________________________________

From: Dakota Kelley <dakotak at teliospc.com>
To: Eddie Corwin <ecorwin at altanova-energy.com>;
equest-users at lists.onebuilding.org
Sent: Wed, September 29, 2010 12:56:13 PM
Subject: RE: [Equest-users] No Heating from PVVT Heat Pump
Water-cooled heat pumps, ground loop or not, are considered system type
PVVT.  Air-cooled heat pumps are considered type PSZ.  Try changing your
system type to PSZ and your heating source to "heat pump".    
 
You can also create a temporary project and set up an air-source heat
pump in the wizard, then go inspect the system type/settings in the
detailed interface to see how eQUEST interprets your inputs.
 
Thanks,
 
                                 
DAKOTA KELLEY 
Project Designer | Energy Analyst
                          
                              Office: 214.744.6199                 
                              Cell: 214.280.3825
                              Fax: 214.744.0770    
 
http://www.teliospc.com <http://www.teliospc.com/>          3535 Travis
St. Suite 115
dakotak at teliospc.com            Dallas, TX 75204

                                
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From: Eddie Corwin [mailto:ecorwin at altanova-energy.com] 
Sent: Wednesday, September 29, 2010 8:43 AM
To: equest-users at lists.onebuilding.org
Subject: Re: [Equest-users] No Heating from PVVT Heat Pump
 
So I determined why I was not getting any heating, and the resolutions
perplexes me.
 
 I am modeling an Air-to-Air heat pump, so in the air-side system -->
Basics tab I selected "NO" for the field "WL/GS Ht Pump".  In doing so,
I get no heating out of the system.  When I change the field to "YES"  I
now get heating.  Attached are two images showing the field i am
referring to, and showing that I have an air-cooled condenser.  Does
anyone know why this might be happening.  I am worried that eQuest is
treating my HP like a ground or water source HP instead of an air-to-air
system.  Any thoughts on the matter would be appreciated.  By the way, I
am using eQuest 3.64
 
-Eddie
 
 
________________________________

From: Eddie Corwin <ecorwin at altanova-energy.com>
To: equest-users at lists.onebuilding.org
Sent: Tue, September 28, 2010 5:17:21 PM
Subject: [Equest-users] No Heating from PVVT Heat Pump
I am trying to model a PVVT system, that uses an air-cooled heat pump
for heating and cooling.  For some reason, the system refuses to supply
any heating.  When I change the condenser type from air-cooled to
water-cooled, the system WILL provide heat.  Has anyone experienced
problems like this, or has someone successful modeled a PVVT air-cooled
heat pump?  I have attached my IDF and PD2 file for review.  
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