Instruction Manual

THREE
EASY STEPS
STEP 2 - (continued)
OPEN COIL vs TUBULAR elements
THERMOLEC man
uf
actures both open coil and tubular duct heaters
.
It is widely ac
kno
wledged that tubular elements find pr
actical application under certain circumstances
(ser
vice conditions include possib
le contact by personnel, presence of dust or par
ticles in the air flo
ws or
atmospheric conditions).
But, where heating filtered air is the sole function, the open coil heater is superior for many reasons:
•
Longer life
•
More kilowatts per square foot
•
Less stratification by equal
distr
ibution of the elements
•
Lo
wer wire surface temper
ature
•
Less maintenance
•
Greater ser
viceability
•
Better heat distrib
ution across
heater f
ace
•
Less pressure drop
•
Lighter weight
•
Low shipping costs
•
Less sensitivity to moisture
•
More flexibility of size
and capacity
•
Cost effective
•
Smaller size
•
Large electrical clearance
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0 300 600 900 1200
.25
.20
.15
.10
.05
Pressure drop (inches of water)
Air Velocity (FPM)
0 100 200 300 400 500 600 700 800 900
14
13
12
11
10
9
8
7
6
5
4
3
2
1
KW / sq. foot / stage
Air Velocity (FPM)
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FPM
Pressure Drop for Tubes
Minimum Air V
elocity for tubes