Trane HUV Installation Operation & Maintenance page 48

Electric Heat Coil Selection
The heating capacity of the electric
fin-tube coil depends solely on the
kW rating of the coil. For selection,
refer to Table P16 or the TOPPS se-
lection program. This table lists
the kW rating of each coil and the
MBh equivalent. Determine the
smallest electric coil that will meet
room heating capacity require-
ments.
Example:
Given:
Total heating requirement = 86.5 MBh
Outside design conditions = 0 F
Steam Coil Selection
The capacity of steam heating coils
is determined by the entering (mix-
ture) air temperature to the coil
and the pressure of saturated
steam to the coil. Select the coil
with a capacity equal to or greater
than the total heating require-
ments. Steam pressures of less
than 5 psi may adversely affect coil
performance.
4 8
Selection Procedure
Electric Heat Coils/Steam Coils
Inside design conditions = 70 F
Outside air = 33%
Classroom air conditioner previously
selected = Size 125
Electric classroom air conditioners
provide safe, functional and eco-
nomical operation, utilizing a new
concept of electric heat coil de-
sign. The Trane electric coil is built
by placing electric heating ele-
ments inside a specially designed
extended surface fin-tube bundle.
This design results in a consider-
Example:
Given:
Total heating requirement = 110.5 MBh
Outside design conditions = 20 F
Inside design conditions = 70 F
Outside air = 27%
Saturated steam pressure = 5 lbs
Classroom air conditioner previously
selected = Size 125
able reduction in fin and element
surface temperatures. Also, the
Trane coil has more even temper-
ature distribution across the ele-
ment. Since coil life expectancy is
dependent upon watt density
(watts per inch of element), tem-
perature at which the coil is oper-
ating and air distribution over the
coil, the unique Trane coil design
helps maximize coil life.
Entering air temp to coil = 70 - [.27 x
(70-20)] = 56.5 F
The K2 coil at these conditions has a
capacity of 111.0 MBh. Therefore, a K2
coil meets the room heating require-
ments.
The air temperature rise = 80 F.
Leaving air temperature = 45.7 + 95 =
125.7 F
Outside design conditions = 20 F.
UV-PRC001-EN