Energy Tech Laboratories MR212 Manuale Utente

 

14

Blower Size  Maximum RPM 

Maximum HP 

10” 1800 

2 

12” 1500 

3 

15” 1400 

5 

18” 1200 

5 

20” 1000  10 
25” 900  20 

Thread Size 

Torque (IN/Lb)

No. 10 (bushing) 

32 

1/4” (bushing) 

72 

5/16” 130 

1.  With the air and burner systems in full operation and all ducts attached, measure the system 

airflow.  Motor sheave (pulley) is variable pitch, and allows for an increase or decrease of the fan 
RPM to adjust the airflow, as shown in the illustration below.  For your convenience, a RPM chart 
is included in the following pages. 

2.  Once the proper airflow is achieved, measure and record the fan speed with a reliable 

tachometer. Caution - Excessive speed will result in motor overloading or bearing failure.  
Do not set fan RPMs higher than specified in the maximum RPM chart.  See the 
troubleshooting guide for more information.  

3.  Measure and record the voltage and amperage to the motor and compare with the motor 

nameplate to determine if the motor is operating under safe load condition. 

4.  Once the rpm of the ventilator has been properly set, disconnect power and recheck belt tension 

and pulley alignment as described below. 

The adjustable motor pulley is factory set for the RPM specified. 
Speed can be increased by closing or decreased by opening the 
adjustable motor sheave. Two groove variable pitch pulleys must 
be adjusted an equal number of turns open or closed. Any 
increase in speed represents a substantial increase in 
horsepower required by the unit. Motor amperage should always 
be checked to avoid serious damage to the motor when the 
speed is varied.  Always torque setscrews according to the 
setscrew torque chart.