[Equest-users] Strange ERV Error and Results

[Dave Weigel]

Thank you Nick, Patrick, and the other responders.  I’m back on track now and experimenting with delta-T.

Best to you,

Dave

From: Nick Caton 
Sent: Thursday, February 27, 2014 10:07 AM
To: Patrick J. O'Leary, Jr. ; The Watt Doctors - Dave Weigel 
Cc: equest-users at lists.onebuilding.org 
Subject: RE: [Equest-users] Strange ERV Error and Results

I have the vague impression that “maximum tracked changes” messages have something to do with the user interface and do not generally seem to affect an actual simulation (erroneous warnings).  I’ve encountered the same warning across many projects without any apparent detrimental effects.

 

I don’t think I’ve seen this warning addressed in any official capacity however, so it would be prudent to maintain a backup of your project prior to or immediately after receiving this message for the first time, and take note of what change evoked that response, in case you later want to backtrack. 

 

I’d reinforce Patrick’s response, and also layer on to consider pressure drop / fan heat while you’re at it…  Fred Betz summarized this pretty well a few months ago (attached).  It’s tempting to assume a cooling energy “jump” must be solely caused by additional outside air loads, when adding ERV, but your fans working harder can easily be a good chunk of that figure as well.

 

~Nick

 



 

NICK CATON, P.E.

SENIOR ENGINEER

 

Smith & Boucher Engineers

25501 west valley parkway, suite 200

olathe, ks 66061

direct 913.344.0036

fax 913.345.0617

www.smithboucher.com 

 

From: equest-users-bounces at lists.onebuilding.org [mailto:equest-users-bounces at lists.onebuilding.org] On Behalf Of Patrick J. O'Leary, Jr.
Sent: Thursday, February 27, 2014 5:34 AM
To: The Watt Doctors - Dave Weigel
Cc: equest-users at lists.onebuilding.org
Subject: Re: [Equest-users] Strange ERV Error and Results

 

how is the erv controlled?  if you take the default on when ahu supply fan unit is on then it will cost you more energy as the erv runs continuously even when there is a) no advantage to do so, and b) when it is detrimental to do so.  try changing control to a delta t between exhaust air and outside air temp via a eem & play with the delta.  my experience in southern arizona is that a 27 d t is optimum where i am at.

On 2/27/14 2:17 AM, The Watt Doctors - Dave Weigel wrote: 

Hi Group,

 

My system is a simple VAV. When I click to add an ERV, it ties up my machine completely for about 3-4 minutes and then throws up the error for “maximum number of tracked changes exceeded.”  But it accepts the ERV and lets me configure it.  This results in a vast decrease in heating energy, but a large increase in cooling energy. Weather is Atlanta.  I don’t understand why cooling energy would increase with the simple addition of an ERV.

 

Any thoughts?  

 

Thanks!

 

Dave






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