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<font size="+1">Hi Deepika,</font><br>
<font size="+1"> No you are not misunderstanding the software but
you have to dig deeper into why in the simulation output. On an
early auto-size run this is pretty standard. There can be several
reasons for this depending on how your model and zoning are set
up. </font><font size="+1">The first page will give you clues,
Simulation Messages for Review.</font><font size="+1"> Then I
normally start with LS-B peak load components, to get an idea of
what is happening in each zone without the outside air. Then SV-A
which gives the HVAC unit sizing and fresh air values. Then SS-J
Peak Heating and cooling. This will give you the peaks, hours
operating etc. and times when the loads are not met. Last but not
least SS-O, space temperature summary. Many times I do a spread
sheet to organize the peak data, watch the times of day.<br>
There are several areas to key on initially. First, coming
off night setback, if you have a heavy building it won't come up
to temperature in one hour. Location of your control zone for
temperature control, if you have it in the wrong zone that zone
will be fine but the other ones will not. Try to have it in the
zone with the heaviest loads, but be warned this might not work
either because a light zone then could run over hot or over cold
too. You can play with the location to find the best spot. Check
your air flows and delta T's, eQuest defaults to 0.5 cfm/sf, many
times this is too low. You may not have enough air flow to carry
the load. You might have a group of zones which you lose control
of in the afternoon because of a wall of glass on the west side.
You can also play with the throttling range as well, take it up to
4 degrees from 2 but only do this as a last resort to make up for
light or heavy zones once you know the reasons behind your high
hours out of range. It can mask real problems with your design.
It is all detective work once you get the program running. You
have to sort though your output data and figure out what is
happening, what is out of line and why. Then you start
adjusting. <br>
Face it, computers and software are dumb as a post. They are
just tools and eQuest will never pop out a building on auto-size
first go. Everything depends on the skill of the operator and
deciphering the clues. You have 1800+ pages of data which will
tell you everything you need to know.<br>
Bruce Easterbrook P.Eng.<br>
Abode Engineering<br>
</font><br>
On 11/08/2011 07:53 PM, deepika khowal wrote:
<blockquote
cite="mid:CAHKrw7WQfF9JyAN0pyp2yJ-eLAgmdxVzb0r8wvU5+j9WXD90Fw@mail.gmail.com"
type="cite">Hi All
<div>I am working on existing building EEM model</div>
<div>I had existing HVAC unit of 20 ton for a space which showed
4000 hrs outside throttle range.</div>
<div>when I autosize the unit, the size becomes 10 tons showing
the building was too oversized but still the model showed 2000
hrs outside throttle range.</div>
<div>I would believe if equest is sizing the equipment, we wont
see any unmet hours.</div>
<div><br>
</div>
<div>Am I understanding something wrong about the software?</div>
<div>Thanks</div>
<div><br>
</div>
<div>Regards</div>
<div>
Deepika</div>
<br>
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<br>
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