[Equest-users] design flow input vs. SV-A supply flow reporting

[Nick Caton]

First, thanks to Carol for elevating my understanding of elevation in
eQuest  (see what I did there??? it's a Friday alright)...  

 

That was always a mystery to me and I'm finding elevation is indeed the
source of my CFM's bumping up (not doubling though) on at least one
previous project.

 

That said, Paul:  

 

I'm pretty sure you can expect any entered zone-level design airflows
(including exhaust) to potentially override or otherwise mess with
system level airflow inputs if/when they ever sum to be larger.  

 

If you specify a system-level design airflow which is below what the
loads require but not in conflict with any zonal inputs, eQuest appears
to simply adjust upwards for elevation if >0, then upward to the limits
of your entered max-flow-ratio, then follows through and spits back
unmet load hours in the results, as you'd expect, but importantly will
not inflate your system's design CFM beyond the max-flow ratio to
compensate for unmet loads - so it may be good to know whatever is
doubling the specified CFM in your model is probably not related to your
load inputs.  

 

Oh yeah, the system sizing ratio (found on the first tab opening any
airside system) will inflate your airflows too if it's above 1.0 -
better check that.

 

Sidenote: The fasted way I know of to check resulting airflow results is
to be aware of the summary tab.  After a calc, highlight a system within
(or the project at the top of) the component tree under air-side HVAC
and click the summary tab underneath the toolbars.

 

~Nick

 

 

 

NICK CATON, E.I.T.

PROJECT ENGINEER

25501 west valley parkway

olathe ks 66061

direct 913 344.0036

fax 913 345.0617

Check out our new web-site @ www.smithboucher.com 

 

From: equest-users-bounces at lists.onebuilding.org
[mailto:equest-users-bounces at lists.onebuilding.org] On Behalf Of Matthew
W. Higgins
Sent: Friday, October 08, 2010 10:54 AM
To: Paul Diglio; Carol Gardner; cstalberg at naturalintelligence.us
Cc: equest-users at lists.onebuilding.org
Subject: Re: [Equest-users] design flow input vs. SV-A supply flow
reporting

 

Depending on your system type (VAV) I've found that you need to ensure
your Min and Max flow ratios are set at 1.0 for each system, if
appropriate. While the system sizing ratio is one thing, flow ratios are
another. 

 

But maybe you've tried that already, I don't know...

 

Matthew Higgins, ASHRAE-HBDP, LEED-AP

Energy Engineer

 

Bridgers & Paxton Consulting Engineers, Inc.

4600-C Montgomery Blvd. NE

Albuquerque, NM  87109

505-883-4111

505-888-1436  Fax

mwhiggins at bpce.com 

 

www.bpce.com

 

From: equest-users-bounces at lists.onebuilding.org
[mailto:equest-users-bounces at lists.onebuilding.org] On Behalf Of Paul
Diglio
Sent: Friday, October 08, 2010 9:06 AM
To: Carol Gardner; cstalberg at naturalintelligence.us
Cc: equest-users at lists.onebuilding.org
Subject: Re: [Equest-users] design flow input vs. SV-A supply flow
reporting

 

Carol:

I am having the same problem with airflow almost double from what I
specified.  I tried the altitude correction and that did not help.

Does the zone air flow and exhaust rate take preference over the fan
flow parameters?

Thank you,

Paul Diglio

 

 

________________________________

From: Carol Gardner <cmg750 at gmail.com>
To: cstalberg at naturalintelligence.us
Cc: equest-users at lists.onebuilding.org
Sent: Fri, October 8, 2010 9:33:46 AM
Subject: Re: [Equest-users] design flow input vs. SV-A supply flow
reporting

Not stupid at all, If you have your altitude set to anything but 0
eQUEST will adjust your cfm accordingly. I always go in and set it
manually to zero. I think it reads what it is off the weather file.

Carol

On Fri, Oct 8, 2010 at 6:54 AM, Christian Stalberg <
cstalberg at naturalintelligence.us> wrote:

They say no question is a stupid question.

 

Why is my zone level supply flow cfm reported value in the SV-A report 

higher than my overall design flow (ASSIGNED-FLOW) value? The 

system sizing ratio is set at 1.00 (default).

 

Thanks in advance.


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-- 
Carol Gardner PE

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