[Equest-users] ERV on OA-From-System Comments from Jeff Hirsch

[Paul Diglio]

Just wanted to share an e-mail from Jeff.  I did not know that an ERV on a 
OA-From system was not supported by eQuest.  That explains why I could never get 
the correct airflows on this type of design.

Unfortunately almost every project I work on does specify a VAV DOAS with an ERV 
to supply ventilation air to some type of HVAC system, such as VRF indoor coils, 
chilled beams or PTHP units.  I will have to try the work around Jeff suggested.

 Paul Diglio, CEM, CBCP


87 Fairmont Avenue
New Haven, CT  06513
203-415-0082


www.pdigliollc.com



----- Forwarded Message ----
From: Jeff Hirsch <James.J.Hirsch at gmail.com>
To: Paul Diglio <paul.diglio at sbcglobal.net>
Sent: Mon, June 3, 2013 12:17:58 PM
Subject: Re: [Equest-users] OA From System Question


Setting your OA system (ERU1) to be vav  and having the ERV on it will not work 
correctly.  If you need ERV you must  place your ERV in the IU system and use 
that system to supply the conditioned  OA.  ERV on a OA-FROM system is not 
supported.  VAV on an OA-FROM  system is possibly not what you want but I cannot 
tell what you are trying to  do.  An IU system has a central constant volume air 
supply with each zone  then having zone coil to do the zone thermostat 
controlled conditioning via room  air flow induced as a constant ratio supply 
air fro the IU (the  induction-ratio). So it seems you can use the IU system as 
your ERU system  supplying the zones. If there is some other reason you used an 
OA-FROM system,  then perhaps my suggestions don’t apply, but the ERV and VAV 
comments always  apply.
 
 
________________________________
 Jeff Hirsch
James J. Hirsch  & Associates
12185 Presilla Road -  Camarillo, CA 93012-9243 USA
phone: (805) 553-9000 mobile: (805) 532-1045 fax: (805) 532-2401
email: James.J.Hirsch at gmail.com
 
From: Paul Diglio 
Sent: Monday, June 03, 2013 6:11 AM
To: equest-users at lists.onebuilding.org 
Subject: [Equest-users] OA From System Question
  Morning:

I  am trying to model a chilled beam system as induction units.  The primary  
air is supplied by an ERU.  I set the outside air to 0 on the chilled beams  
HVAC systems tab.

In the chilled beam zone tab I set the outside air to  the primary CFM and the 
overall CFM to the induced air flow.

Per the  eQuest help menu, "The sum of the OA requirements for all SYSTEMs that 
reference  an OA-FROM-SYSTEM is used to set the referenced OA-FROM-SYSTEM value 
for  MIN-OUTSIDE-AIR, SUPPLY-FLOW as well as adjust the referenced 
OA-FROM-SYSTEM  directly served ZONE maximum and minimum flows for both heating 
and cooling." 


But per my hourly reports, the ERU is not supplying the necessary amount  of 
primary air and in the summer the ERU flow drops to .01 CFM.

Attached  are the project files.  Any ideas?

Thank you,

 Paul Diglio, CEM, CBCP


87 Fairmont Avenue
New Haven, CT 06513
203-415-0082


www.pdigliollc.com 
 
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