Trane Gas Unit Heaters Katalog

16

 UH-PRC002-EN

Determine the total heating load requirements in accordance with methods recommended by the 
ASHRAE Handbook of Fundamentals or other acceptable means.

1.

From the performance data tables, select the unit whose heating output meets or exceeds the 
heating load requirement.

2. Airflow (cfm) and temperature rise can be read directly from the performance data tables.

3. Knowing the mounting height of the unit, throw can be determined from the performance data 

table. If the throw is not adequate, consider using a larger propeller fan unit heater or a 
centrifugal fan unit heater with an optional discharge nozzle for greater throw.

Selection Example—A natural gas propeller fan unit heater that can provide 75 MBh heating 
output is required. The unit will be mounted 10 feet above the floor and a 40-foot throw is 
required.

Select the unit as follows:

a. From 

, select a GHND-010 with 100.0 MBh input and 80.0 MBh heating output, 

1,480 cfm and a 50°F temperature rise.

b. From 

, throw at a mounting height of 10 feet is 54 feet.

1.

From the performance data tables, select the unit whose heating output meets or exceeds the 
heating load requirement.

2. Airflow (cfm) ranges are listed for each unit size in the performance data tables. Knowing either 

the desired airflow or temperature rise, the other can be calculated using the following 
formulas:

3. Knowing the mounting height of the unit, throw can be determined from the performance data 

table. If the throw is not adequate, a discharge nozzle can be used to obtain additional throw.

Selection Example—An LP (Propane) gas centrifugal fan unit heater that can provide 150 MBh 
heating output is required. An airflow of 2,000 cfm is desired. The unit will be mounted 12 feet 
above the floor and a 65-foot throw is required.

Select the unit as follows:

a. From 

, select a GBPD-020 with a 200.0 MBh input and 160.0 MBh heating 

output. An airflow of 2,000 cfm is within the allowable range, and temperature rise is 
calculated as follows:

b. From

, throw at a 12-foot mounting height is 61 feet. As a 61-foot throw is not 

adequate, a 60-degree nozzle can be selected (from 

) which provides a throw 

of 76 feet.

cfm =

Output x 1,000

1.085 x ΔT

ΔT =

Output x 1,000

1.085 x cfm

ΔT =

MBh x 1,000

1.085 x χφμ

ΔT =

160 x 1,000

= 74.0°F

1.085 x 2,000