[Equest-users] Fixing unmet hours / outside of throttling range warnings

[Paul Diglio]

Mark:

Since you are using the as-designed HVAC system, you cannot increase the airflow 
and still be compliant with the design.

I have had some success in reducing unmet hours by increasing the thermostat 
throttling range as long as the increased range is consistent with the Owner's 
Project Requirements for space temperature limits.  I also have had some success 
by choosing a different control zone in the Airside Systems Basic tab.  This 
depends if you have more than one zone per system.  Look at the SS-R Zone 
Performance Summary reports to see which zone(s) is giving you trouble.

If you have multiple zones per system and increasing the throttling range or 
changing the control zone does not work, try imputing the airflow on the Zone 
level instead of the System level.  If you input the supply CFM in the System 
tab, return that to default and divide up the design airflow in the zones.  I 
would reduce the CFM in those zones that have 0 unmet hours and increase the CFM 
in those zones that have high unmet hours.  The SS-R report will show how eQuest 
has allocated the supply CFM.

Paul Diglio




________________________________
From: John Aulbach <jra_sac at yahoo.com>
To: Mark Darrall <MDarrall at a2so4.com>; equest-users 
<equest-users at lists.onebuilding.org>
Sent: Mon, May 2, 2011 1:00:01 PM
Subject: Re: [Equest-users] Fixing unmet hours / outside of throttling range 
warnings


Mark:
 
Either spread your thermostat throttling range, or incrase your total supply 
airflow.
 
John R. Aulbach, PE, CEM
Senior Energy Engineer

________________________________
 
PartnerEnergy
1990 E. Grand Avenue, El Segundo, CA 90245
W: 888-826-1216, X254| D: 310-765-7295 | F: 310-817-2745
www.ptrenergy.com| jaulbach at ptrenergy.com 
 




________________________________
 From: Mark Darrall <MDarrall at a2so4.com>
To: equest-users <equest-users at lists.onebuilding.org>
Sent: Mon, May 2, 2011 6:21:24 AM
Subject: [Equest-users] Fixing unmet hours / outside of throttling range 
warnings

 
Good Morning, eQUESTers,
 
I’m working on my design case model. Here’s my ATTN report:
 
**WARNING**********************************************************************
             SYSTEM EL1 Sys1 (PSZ) (G.NNW1)          may have inadequate cooling 
capability
             Check COOLING-CAPACITY and MIN-SUPPLY-T for consistency
 
**WARNING**********************************************************************
             SYSTEM EL1 Sys2 (PSZ) (G.WSW2)          may have inadequate cooling 
capability
             Check COOLING-CAPACITY and MIN-SUPPLY-T for consistency
 
**WARNING**********************************************************************
             SYSTEM EL1 Sys3 (PSZ) (G.N3)            may have inadequate cooling 
capability
             Check COOLING-CAPACITY and MIN-SUPPLY-T for consistency
 
**WARNING**********************************************************************
             SYSTEM EL1 Sys4 (PSZ) (G.S4)            may have inadequate cooling 
capability
             Check COOLING-CAPACITY and MIN-SUPPLY-T for consistency
 
**WARNING**********************************************************************
             SYSTEM EL1 Sys5 (PSZ) (G.N5)            may have inadequate cooling 
capability
             Check COOLING-CAPACITY and MIN-SUPPLY-T for consistency
 
**WARNING**********************************************************************
             SYSTEM EL1 Sys6 (PSZ) (G.E6)            may have inadequate cooling 
capability
             Check COOLING-CAPACITY and MIN-SUPPLY-T for consistency
 
**WARNING**********************************************************************
             SYSTEM EL1 Sys7 (PSZ) (G.C7)            has zero outside air for 
design calculations
 
 
This last one I can answer as this system is a R/A only computer room cooler. 
For the others:
 
COOLING-CAPACITY comes directly from the HVAC designer and is the capacity of 
the installed units. I’ve tried adjusting MIN-SUPPLY-T from 55 to 50 (and this 
seems to jive with information the coil manufacturer provides) to get a larger 
delta-T and it only seemed to make things worse somehow. Minimum OSA is 20%, but 
again, this is a design condition. These units do have enthalpy-controlled 
economizers.
 
I’m also getting WAY too many hours outside of throttling range – 15%. My 
baseline model only has a 3%. I’m way out of whack with Appendix G requirements.
 
Any suggestions as to settings to modify to clear these? Thank you!
 
MARK DARRALL, AIA, LEED AP BD+C, NCARB
Senior Project Manager
 
 
DESIGN ENRICHING LIFE // LIFE ENRICHING DESIGN
 
A2SO4 Architecture, LLC
Union Station
300 South Meridian Street / 250
Indianapolis, Indiana 46225
TEL  317 388 8850
FAX  317 280 0692
MOB 765 749 0841
www.a2so4.com
 
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