[Equest-users] erv static vs kw/cfm

Patrick J. O'Leary, Jr. poleary1969 at gmail.com
Mon Feb 27 14:49:01 PST 2012


has anyone ever noticed a difference in simulation results when using a 
sensible wheel and kw/cfm power input versus a sensible wheel and static 
pressure thru the heat exchanger input?

for example, i have an existing building of about 60,000 sf and i have a 
test & balance report for it.

if i simulate the building and use a site measured static through the 
erv heat exchanger section (sensible wheel, typically about 0.73" wg) 
the building has a cost difference of $7,037 dollars less than if i 
simulate the same building using the site measured kw/cfm input 
(typically about 0.0006 kw/cfm oa supply fan, 0.0012 exhasut air fan).

i have previously found this is not limited to a field measurement 
situation.  any project i've simulated where there's been an erv in the 
design performs more cost effectively using the manufacturer's catalog 
data for static input instead of the manufacturer's catalog data for 
kw/cfm (or kw).

if kw/cfm and static are both entered equest still uses the kw/cfm for 
the calculations - at least that is how i'm reading the help function.  
if kw/cfm (or kw) are not entered then either the default static (1" wg) 
or user entered static are used.


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