[BLDG-SIM] Trouble with Heat Pumps (eQuest)

[Brandon Nichols]

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-pump
s.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

 

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 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 


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