[Equest-users] UA Convergence Error

[Sharad Kumar]

Hi Paul,

I think the problem is being caused due to some heat exchanger kind of
thing being modeled in the built.

I am guessing out the problem as follows:

The UA calculations does not converge as there can be might possibility
that then UA product and after multiplication with delta T does not
converge with the meeting of the capacity as the formula is Q= U* A* delta
T.

Q=  Capacity
UA= product of conductance and cross sectional area.
delta T= Temperature difference between ends.

[image: image.png]

Hence try to succumb with the problem in lieu-wise as above.


[image: image.png]

The other factors to have the UA product calculations to be right are as in
above help page super-script which might can also guide as there are other
factors based calculations is there as if there the boxed figure are outrun.

Hope this might help.

*Thanks and regards,*
Sharad.Kumar
Freelancer-Energy Simulation and Day-lighting.

*....................................................................................................................................................*
.

---------- Forwarded message ----------
From: Paul Diglio <paul.diglio at sbcglobal.net>
To: Equest-users <equest-users at lists.onebuilding.org>
Cc:
Bcc:
Date: Mon, 9 Dec 2019 11:13:13 +0000 (UTC)
Subject: [Equest-users] UA Convergence Error
Hi Folks:

I am getting a "heat exchanger XX Sys1 UA calculation failed to converge"
error.  The model has three building in it and only two air handlers per
building.  I don't have any heat exchangers attached to the air handlers or
any heat recovery installed.

Sometimes the error occurs when I change the glass type via the library and
other times I get the error when I adjust the air changes per hour in one
or two zones.

In the example above, the error was for system B2, but it
varies...sometimes systems A or C 1 or 2.

Any ideas what the problem could be?

Thank you,

Paul Diglio
87 Fairmont Avenue
New Haven, CT 06513


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