Simulating an exhaust fan to cool a transformer room

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Has anyone had any luck simulating the use of an exhaust fan drawing
fresh air through a louver to cool a transformer room?

Matt Scott

N.E. Fisher & Associates, Inc.

329 East Second St, 2nd Flr

Boyertown, PA 19512

e: mscott at nefisher.com

p: 610-369-3190

f: 610-369-3194

Matthew Scott's picture
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Hi Matthew,

I have not been 100% successful in doing this through a system.

Instead I do the following;

. Set up a space with the proper load components from the
transformer and building skin and then give it an infiltration rate that is
equal to the airflow of my exhaust fan.

. Then that space gets assigned to a system with no cooling or
heating.

. From there obtain a design report for the Hourly Zone Loads for
the space. This gives a temp at every hour for each month, 288 total temps.

. Scan this for any hours where the temperature is below the EF to
T-stat design set-point by some range.

. Any hours that are below this set-point by a certain "range" get
multiplied by the number of days in that month and subtracted from 8760
hours.

. For the "range" mentioned above I remove the infiltration load
from the space and re-run the design report for the Hourly Zone Loads. The
temperature difference between the OA Temp and Zone Temp of this new run,
with no infiltration, is my allowable "range". If Zone Temp is 105F and OA
temp is 80F then my range is 35F. So any hours in the first run, (the run
with infiltration), 35F below my desired set-point are assumed to not need
fan operation.

. Remember to schedule the transformer load properly otherwise all
hours will be hot.

. At the end there will be some number of hours less than 8760 that
gets multiplied by the fan bhp and added to the Building Misc. Energy tab of
the Building Properties.

That's the best I have come up with. Hopefully it helps!

Regards

Joe Fleming | PE, LEED AP BD+C, BEMP

Commissioning Agent / Energy Modeler | The Spinnaker Group

561.602.3132 | joe at thespinnakergroupinc.com

Joe Fleming's picture
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Sorry, 35F should read 25F

Joe Fleming | PE, LEED AP BD+C, BEMP

Commissioning Agent / Energy Modeler | The Spinnaker Group

561.602.3132 | joe at thespinnakergroupinc.com

Joe Fleming's picture
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I did that once using CAV DX unit.

I cant exactly remember because I don't have HAP in front of me but it
should go something like this:

1. you set up your room as usual. allow for some small quantity of
outdoor air in l/s
2. Set up DX CAV airhandler and choose supply air by quantity not
temperature. Use same amount of supply air as outdoor air in step 1
3. use direct exhaust from zone and set it up at same amount of air as
in step 1 and 2
4. use indoor temperature that you are targeting.
5. run hap and look at the coil load. If coil load is positive figure
increase air quantities in step 1, 2 and 3
6. run hap again and keep increasing air quantity until you get 0 for
coil load

And that should be it than.

Regards

Dusko Nikolic's picture
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Thanks all for your suggestions.

Matt Scott

N.E. Fisher & Associates, Inc.

329 East Second St, 2nd Flr

Boyertown, PA 19512

e: mscott at nefisher.com

p: 610-369-3190

f: 610-369-3194

Matthew Scott's picture
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Joined: 2016-05-18
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Thanks all for your suggestions

Matt Scott

N.E. Fisher & Associates, Inc.

329 East Second St, 2nd Flr

Boyertown, PA 19512

e: mscott at nefisher.com

p: 610-369-3190

f: 610-369-3194

Matthew Scott's picture
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Joined: 2016-05-18
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