[BLDG-SIM] Water-to-Water Heat Pump Chillers and GLHE's
Jeff Staller
jstaller at ctgenergetics.com
Fri Feb 23 14:04:29 PST 2007
Mike,
Indeed it is difficult to get all zones into the t-stat throttling range with 2-pipe fan coils; especially important for LEED certification if the building is being simulated based on ASHRAE Appendix G requirements. I've tried the setting up the 2-pipe circulation loop control with a SNAP command and base it on outdoor air temp (55° F for Boston area) but the hours still exceed 3%. I will try the SCHEDULE command to see if I get less under cooled/heated hours.
Thank you,
Jeff
Jeff Staller
CTG Energetics
949-428-6293
________________________________
From: Mike Tillou [mailto:miket at etcgrp.com]
Sent: Friday, February 23, 2007 1:24 PM
To: Jeff Staller; BLDG-SIM at gard.com
Subject: RE: [BLDG-SIM] Water-to-Water Heat Pump Chillers and GLHE's
Jeff,
My experience is that it takes some effort to properly calibrate a 2-pipe system in eQuest, especially if you're trying to get all your zones into the t-stat throttling range so you don't have a lot of unmet heating and cooling hours. I've had the most success operating the 2-pipe circulation loop using the SCHEDULED command. You can define a heating and cooling schedule of type ON/OFF/TEMP where the temp value you enter is either a zone or outside air lockout temp. Leave yourself enough of a deadband to minimize bouncing back and forth between heating and cooling on an hourly basis. You may also need to disable heating or cooling during certain parts of the year (ie: You may not want your system to switch from cooling to heating for 1-2 hours because of a cold August morning.)
Mike
Michael Tillou, PE
ETC Group - Energy Engineering for a Sustainable Future
Ph:413-458-9870
-----Original Message-----
From: BLDG-SIM at gard.com [mailto:BLDG-SIM at gard.com] On Behalf Of Jeff Staller
Sent: Friday, February 23, 2007 1:57 PM
To: BLDG-SIM at gard.com
Subject: [BLDG-SIM] Water-to-Water Heat Pump Chillers and GLHE's
In eQuest I am attempting to model a proposed system that utilizes a 'well-water-to-water heat pump' type chiller that will be attached to a vertical well ground loop heat exchanger. The chillers are modular and cycle on and off to meet demand, so they operate at a constant efficiency. They will be providing HW and CHW to 2-pipe fan coil units. The DOE2.2 documentation indicates this chiller type is Heat-Pump and that this chiller type can only be attached to lake/well water loop. By selecting the lake/well water loop, I am unable to define the vertical well characteristics, i.e well depth, configuration, etc. Does anyone know of a way to attach the Heat-Pump type chiller to a vertical well system? If not, is there a method to better describe the capacity of the lake/well loop? And finally, does anyone have experience modeling this system type and can provide any insight?
Thanks,
Jeff
Jeff Staller, CEM
CTG Energetics
949-428-6293
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