[Equest-users] outside throttling range

[Nick Caton]

A couple thoughts after a quick review:


1.       Your exterior wall construction is brick + CMU with no insulation - in Ohio.  Your roof also features zero insulation.  Comfort conditions are tough to maintain in a climate with extremes for both seasons when the envelope lets all your heating out or all the outside heat in.

2.       You've locked in a CFM, heating supply temp, and cooling supply temp caps for a "per zone" system in the wizards.  This means if one zone ends up needing more airflow for your set temperatures to satisfy the space condition, eQuest is locked into what you've specified and you get unmet hours that way as well.

Suggestions:

-          Improve the insulation for your envelope construction in consideration of your climate (re: ASHRAE 90.1 prescriptive tables for a simple place to start).

-          Allow eQuest to auto-size the airflows with a sizing factor (default is 1.15, iirc), specify a higher flow, and/or define distinct systems @ one per zone so that you can account for the varying design airflows required.

-          In my experience the wizards can have trouble auto-sizing heating-season dominated furnace systems.  In turn you might need to knock up the supply airflow factor accordingly to get things sized correctly if you are left with only unmet heating hours.

~Nick
[cid:489575314 at 22072009-0ABB]

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 tim
Sent: Tuesday, September 18, 2012 2:27 PM
To: equest-users at lists.onebuilding.org
Subject: [Equest-users] outside throttling range

Any ideas why so many unmet hours in the attached model?

It's a simple building with 7 zones each with a PSZ on the roof.

Not sure if I am included all the necessary files so please let me know if you need more.

Thanks,
Timothy W. Hill
tim.JRGA at fuse.net<mailto:tim.JRGA at fuse.net>

John R. Grier, Architect
11309 Deerfield Road
Cincinnati, Ohio 45242
(513)489-3690

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