[Equest-users] Heating mode stuck at minimum flow rate

[Paul Diglio]

Rosie:

What is your thermostat throttling range?

Try 4 degrees and see what happens.

Paul Diglio




________________________________
From: Roselin Osser <Rosie at buildingscience.com>
To: equest-users at lists.onebuilding.org
Sent: Sun, January 16, 2011 9:24:30 PM
Subject: [Equest-users] Heating mode stuck at minimum flow rate


Hi folks,
 
I’m modeling a packaged VAV system (PVAVS) serving only one zone.  The maximum 
airflow the unit can provide is 450,000 cfm, which I have entered in as an 
airflow parameter.  The problem is that whenever the system goes into heating 
mode, the total cfm goes to minimum airflow (observed from hourly output), even 
when more heating is needed, so I end up with a lot of underheated hours.  The 
minimum airflow is calculated from the 10% outdoor air ratio I have entered.  I 
have tried adjusting the HMAX-FLOW-RATIO field to allow the heating airflow to 
go above the minimum if necessary, but the field seems to have no effect.  I 
have a reverse action thermostat in the zone.  Anyone else run into this?  There 
must be some other parameter I’m  using that is preventing the field from 
working.  Any advice would be appreciated, as I have tried a lot of input 
variations and none of them allowed the heating minimum flow to increase when 
more heat is needed.  I’m using eQuest 3.64.
 
Thanks for your help!
 
Rosie
 
 
Roselin Osser, BEMP, LEED AP
Building Science Corporation
30 Forest Street
Somerville, MA  02143
978-589-5100 x 5284
fax:  978-589-5103
 
Building Science Corporation
Somerville MA  |  Waterloo ON
www.buildingscience.com
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