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Washburn, F. E. (ed.) / The Wisconsin engineer
Vol. 5, No. 2 (May 1901)

Zimmerman, O. B.
Some results of a test of heating and ventilating apparatus,   pp. 194-201


Page 198


The WXisconsin Engineer.
  If again, here, we consider the drip returned to the boilers
our percentage goes up to i00%.
  Following the heat to the rooms we deal with the enormous
losses in this type of plant as a heating system. Part of the heat
losses are radiation through the room walls and through the
w indows, others are by escaping air through cracks about the
windows and lastly by heat losses up through the ventilators.
  We can reduce this then to a formula of the total efficiency
as far as heating goes,
      Heat delivered to the rooms - heat going out of ventilators
                        Total heat in coal.
     E = Total volume of air in cubic feet delivered to the rooms
in any dlefinite time as per minute.
  F = Weighlt of air per cubic foot.
  Ga = Specific heat of air.
  T = Temperature of the entering air.
  T' = Temperature of the escaping air.
                      E X F X G (T -T')
                  B. T. U. used per min in coal
  - approximately 4.1 % in this building and under these condi-
tions. The average complete change of air from readings taken
at the fan openings and at 6i.40 F. was once in every 6.56
minutes. This same volume corrected for a decrease in pressure
and rise in temperature to 73.6f would give a complete change of
air every 6.3I minutes. Careful readings in all the rooms with
anemometers gave an average change of air every 7.i minutes.
This difference of ii% may easily be accounted for by leakages
througih cracks and also inaccuracies in the reading of instru-
mlents.
  Referring to Plate I we have a comparative scale of tempera-
tures in the heating plant. On the right are given the tempera-
tures in the Fahrenheit scale, on the left, in the Centigrade. This
shows the gradual rise in temperature of the air from the ex-
ternal air curve to that of the hot air roomis.
   The coils in the plant were so arranged as to be practical-
ly two complete sets, one-half feeding the east section and the
other half the western. A continuous series of readings during
the winter gave the average of the west hot room about ten
19S)


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