[Equest-users] No Heating from PVVT Heat Pump

[Eddie Corwin]

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          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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