acutherm Acu-Zone I User manual

Form # 70.0 IOM-001 REV 0603
Copyright Acutherm 2006 1
Acu-Zone I & II
Electric Zone Heaters
Application, Selection
and Specification
Manual
Acu-Zone™ I
Heating Unit
Round Sizes:
6ӯ, 8ӯ, 10ӯ, 12ӯ
Acu-Zone™ II
Heating Unit
Round Sizes:
14ӯ & 16ӯ
Acu-Zone™ II
Heating Unit
Square and
Rectangular

Form # 70.0 IOM-001 REV 0603
Copyright Acutherm 2006 2
Acu-Zone™ Heater Models
Ac
u
-
Zone™ I Heating Uni
t
(Round)
The Acu-Zone™ I is a specially designed unit that is available
in smaller-sizes like 6ӯ, 8ӯ, 10ӯ, and 12ӯ that will match the
Acutherm Therma-Fuserdiffuser neck sizes. The units should
be applied to Therma-Fuser diffusers that are VAV cooling and
heating and VAV cooling with constant volume heating (warm-up)
- model numbers that have the HC or CW suffix respectively. The
A
c
u
-Zone™ I units should be used on individual diffusers and
on multiple diffusers up to a total of four. Discharge temperature
control is built-in to this unit.
Ac
u
-
Zone™ II Heating Uni
t
(Round)
The Acu-Zone™ II is designed for larger zones that require
primary or supplementary heating. These units are to be used
with the diffuser models indicated above. Discharge temperature
control is accomplished by a remotely mounted discharge
thermostat downstream from the heater.
The Round sizes that are available for this model are 14ӯ and
16ӯ.
Ac
u
-
Zon
e
™ II Heating Uni
t
The Acu-Zone™ II is designed for larger zones that
require primary or supplementary heating. These units are
to be used with the diffuser models indicated above.
Discharge temperature control is accomplished by a
remotely mounted discharge thermostat downstream from
the heater. Units are configured for “slip-in” installation with
flanges OPTIONAL (Consult Factory).
The Acu-Zone™ II heating units can be made in virtually
any rectangular or square size and in any KW and voltage
available.

Form # 70.0 IOM-001 REV 0603
Copyright Acutherm 2006 3
Application Drawing:
SCR Controlled Electric Heater
Acu-Zone™ I
T
S
Ac
u
-
Zon
e
Trunk Duct
Manual Damper
Acutherm Therma-Fuser 
Diffuser
VAV Cooling and Heating or VAV
Cooling with Constant Volume
Heating
Acu-Zone Electric Heater for
Supplementary or Primary Heat
Unit will have wall mounting sensor and SCR heater
control. Internal airflow/temperature sensors (
Acu-
Sensors™)
will modulate the heater capacity (KW) to
match the available airflow and limit the discharge
temperature to 90°F.
8” Min.8” Min.
Acu-ZoneI Wall
Thermostat
Application:Single or
Multiple Diffusers (up to 4)
Single Units: Application
shown to the right with a
single
Acu-Zone space
temperature sensor.
Multiple Units: Application
similar to that shown;
however, the discharge of the
heater will be split among
four up to four diffusers.
(More than four diffusers, use
the
Acu-Zone II system).
Note: Maximum Flexible Duct
to each diffuser should not
exceed 7’-0”

Form # 70.0 IOM-001 REV 0603
Copyright Acutherm 2006 4
D 12-24”
D12-24”
Application Drawing:
SCR Controlled Electric Heater
Ac
u
-Zone™ II
R-PIM
–
Round Pressure
Independence Module
Acu-Zone II Electric Heater
with SCR Control
Main
Duct
Acutherm Therma-Fuser
Diffusers with VAV cooling and Heating
or VAV Cooling with Constant Volume
Heating
Acutherm Square or Rectangular
Pressure Independence Module
Main
Duct
Acu-Zone II Electric
Heater with SCR Control
SP
SP
TR
TR
D
T
D
T
“D” = 1 Duct Diameter
Exam
p
le: 6ӯ Duct
–
“D” = 6”
Acutherm Therma-Fuser
Diffusers with VAV cooling and
Heating or VAV Cooling with
Constant Volume Heating
“D” = = Duct Width
Exam
p
le: 24” Width Duct
–
“D” = 24”

Form # 70.0 IOM-001 REV 0603
Copyright Acutherm 2006 5
Selection of the Acu-Zone™ Heater using
the following three steps:
1. Determine the heater capacity, voltage, and electrical
components desired
2. Determine the duct dimensions, air requirements, and
mechanical options
3. Determine the method of control and then select the
control components
Step 1: Determine the heater capacity, voltage, and
electrical components . . .
Heater Selection
Useful Formulas
BTU Formulas:
(#) BTU’s x 0.29307 = Watts
1 KW = 3413 BTU’s
Using the chart on the following page you can select the correct KW capacity if you know
the CFM and the temperature rise desired. Follow the instructions on the page to easily
select the properly sized heater.
Follow the instructions on the remaining pages to make sure that the KW you select is
supported by the voltage and phase that you have available. Large KW units (over 20)
are seldom available in single phase.
Continued
Acu-Zone I & II
Electric Zone Heater
Application, Selection, &
Specification Manual
Heating Calculation:
BTU = CFM x 1.08(∆T ° F)
KW = (CFM x ∆T) ÷ 3150
∆T = (KW x 3150) ÷ CFM

Form # 70.0 IOM-001 REV 0603
Copyright Acutherm 2006 6
Streamlined KW Selection
Graph
(Step 1)

Form # 70.0 IOM-001 REV 0603
Copyright Acutherm 2006 7
Model AZON I
Size
CFM ∆T °F BTUH KW(Nominal)
6”Ø 100 35°F 3780 1.11
6”Ø 140 35°F 5292 1.58
6”Ø 175 35°F 6615 1.94
6”Ø 200 35°F 7560 2.22
6”Ø 225 35°F 8505 2.50
8”Ø 160 35°F 6048 1.77
8”Ø 225 35°F 8505 2.49
8”Ø 275 35°F 10,395 3.04
8”Ø 320 35°F 12,096 3.54
8”Ø 355 35°F 13,419 3.94
10”Ø 260 35°F 9828 2.88
10”Ø 370 35°F 13,986 4.10
10”Ø 450 35°F 17,010 4.98
10”Ø 520 35°F 19,656 5.76
10”Ø 580 35°F 21,924 6.43
12”Ø 350 35°F 13,230 3.87
12”Ø 470 35°F 17,766 5.20
12”Ø 560 35°F 21,168 6.20
12”Ø 640 35°F 24,192 7.08
12”Ø 720 35°F 27,216 7.97
Select the appropriate Acu-Zone™ I Heating Unit based on the CFM and KW noted that
corresponds to the capacity that you need. Please note that the capacities shown are for
reference only and are based on the Acu-Zone™ I use with the TF-HC. Performance
data is the same for the model TF-CW (constant heating). For other models, use the
desired diffuser’s flow rate in the chart and apply the formula(s) shown on the previous
pages.
Acu-Zone I & II
Electric Zone Heater
Application, Selection, &
S
p
ecification Manual
Acu-Zone™ I - Heating Performance Data:
Selection by Diffuser Capacity (Model TF-HC)

Form # 70.0 IOM-001 REV 0603
Copyright Acutherm 2006 8
Using the following capacity table, select the appropriate model number based on the KW
capacity, voltage, and diameter. Please note that the models shown reflect multiple voltages in
the model number. Pick only one voltage only (i.e. 120/1/60).
Model Collar
Size
KW *Voltage Nominal
CFM Range
**Minimum
CFM
AZONI-6-1120/208/240/277 6ӯ 1 120/208/240/277/1/60 100 60
AZONI-6-1.5120/208/240/277 6ӯ 1.5 120/208/240/1/60 101-140 60
AZONI-6-2120/208/240/277 6ӯ 2 120/208/240/277/1/60 155-199 120
AZONI-6-3208/240/277 6ӯ 3 208/240/277/1/60 200-225 180
AZONI-8-2120/208/240/277 8ӯ 2 120/208/240/277/1/60 160 120
AZONI-8-3208/240/277 8ӯ 3 208/240/277/1/60 225-275 180
AZONI-8-4208/240/277 8ӯ 4 208/240/277/1/60 276-355 240
AZONI-10-3208/240/277 10ӯ 3 208/240/277/1/60 260 180
AZONI-10-4208/240/277 10ӯ 4 208/240/277/1/60 261-370 240
AZONI-10-5208/240/277 10ӯ 5 208/240/277/1/60 371-450 300
AZONI-10-6208/240/277 10ӯ 6 208/240/277/1/60 451-520 360
AZONI-10-7208/240/277 10ӯ 7 208/240/277/1/60 521-580 420
AZONI-12-4208/240/277 12ӯ 4 208/240/277/1/60 350 240
AZONI-12-5208/240/277 12ӯ 5 208/240/277/1/60 351-470 300
AZONI-12-6208/240/277 12ӯ 6 208/240/277/1/60 471-560 360
AZONI-12-7208/240/277 12ӯ 7 208/240/277/1/60 561-640 420
AZONI-12-8208/240/244 12ӯ 8 208/240/277/1/60 641-720 480
* See Page 34 for complete voltages available. Units will accept 50HZ or 60HZ power.
** Minimum CFM through the heater to have the full capacity shown. Unit automatically adjusts
capacity as the airflow decreases.
Ac
u
-
Zone™ I Standard Model
s
–
Capacities & Voltages
Acu-Zone I & II
Electric Zone Heater
Application, Selection, &
S
p
ecification Manual

Form # 70.0 IOM-001 REV 0603
Copyright Acutherm 2006 9
R-PIM Size CFM ∆T °F BTUH KW
6”Ø 510 45°F 24,786 7.27
425 45°F 20,655 6.05
350 45°F 17,010 4.98
275 45°F 13,365 3.92
150 45°F 7290 2.14
83 45°F 4034 1.19
8”Ø 905 45°F 43,983 12.89
750 45°F 36,450 10.68
625 45°F 30,375 8.90
790 45°F 23,814 6.98
300 45°F 14,580 4.28
136 45°F 6610 1.94
10”Ø 1415 45°F 68,769 20.10
1200 45°F 58,320 17.08
1000 45°F 48,600 14.23
765 45°F 37,179 10.89
500 45°F 24,300 7.12
215 45°F 10,449 3.062
12”Ø 2040 45°F 99,144 29.04
1700 45°F 82,620 24.20
1400 45°F 68,040 19.92
1100 45°F 53,460 15.66
700 45°F 34,020 9.96
295 45°F 14,337 4.20
14”Ø 2780 45°F 135,108 39.57
2400 45°F 116,640 34.16
2000 45°F 97,200 28.47
1600 45°F 77,760 22.78
1000 45°F 48,600 14.23
413 45°F 20,072 5.88
16”Ø 3615 45°F 175,689 51.47
3050 45°F 148,230 43.42
2500 45°F 121,500 35.59
1950 45°F 94,770 27.76
1200 45°F 58,320 17.09
541 45°F 26,293 7.70
Indicates Nominal Performance Data – Unit will operate throughout the entire range shown. Consult
the Sound Data before using selections above the Nominal Values.
** Indicates Special Order Units – Allow extra fabrication time (Standard capacities for Acu-Zone™ I
units with 6”Ø, 8”Ø, 10”Ø, and 12”Ø - see table page 8). This unit uses the Acu-Zone™ II wall sensor
with the internal Acu-Sensor™ for discharge temperature control.
Acu-Zone I & II
Electric Zone Heater
Application, Selection, &
S
p
ecification Manual
Performance Data
–
Usin
g
with the R-PIM (Acu-Zone™ II)
Acu-Zone™ I **
Acu-Zone II

Form # 70.0 IOM-001 REV 0603
Copyright Acutherm 2006 10
Power and Voltage Requirements: (Step 1)
Electric utilities refer to the voltage they supply with a nominal figure. The actual voltage
that the electric heater sees may vary over a very wide range. For example, a nominal
voltage of 575V / 3PH / 60 HZ may be called 550, 575, or 600V depending upon the
normally accepted convention at your location.
Designing a heater for 550V when 600V is supplied will result in a current draw increase
of over 10%, and there will be a 20% jump in the KW capacity. This is because the
current is proportional to the voltage, and the KW is proportional to the square of the
voltage. The application of a lower voltage will result in the underperformance of the
heater because of “de-rating” caused by the lower voltage.
Therefore, it is imperative that the correct voltage is chosen and specified.
To insure the utmost safety, Acutherm has chosen the highest voltages for each range
and the voltages are shown in the table below. Heaters designed for lower voltages in
each range are available and will be supplied when the customer specifically requests
the lower voltage.
This voltage standardization reduces the risk of overheating due to the heater being
supplied with over-voltage. This overcapacity could result in the nuisance tripping of the
high temperature cut-outs.
Acu-Zone I & II
Electric Zone Heater
Application, Selection, &
Specification Manual
Common
Nominal
Voltages
110
115
120
208 220 230
240
277 318
332
347
380 416 440
460
480
550
575
600
Acutherm
Standard
Voltages
120 208
1
PH
208
3
PH
220
1
PH
240
1
PH
240
3
PH
277
1
PH
347
1
PH
380
1
PH
380
3
PH
416
1
PH
416
3
PH
480
1
PH
480
3
PH
600
1
PH
600
3
PH

Form # 70.0 IOM-001 REV 0603
Copyright Acutherm 2006 11
Single Phase Power Supply – 347 & 277V (Step 1)
When capacities are below 7 KW at 277 V and 8KW at 347 V, Acutherm recommends the use of
the following arrangements to obtain the most economical cost for heaters and electrical
distribution
Acu-Zone I & II
Electric Zone Heater
Application, Selection, &
Specification Manual

Form # 70.0 IOM-001 REV 0603
Copyright Acutherm 2006 12
Acu-Zone I & II
Electric Zone Heater
Application, Selection, &
Specification Manual
Selection Chart for the most economical design for
Acu-Zone™ Heaters – KW / Voltage Combination (Step 1)

Form # 70.0 IOM-001 REV 0603
Copyright Acutherm 2006 13
Fusing: (Step 1)
The National Electric Code requires that each power supply to a heater be
individually protected by either fuses or circuit breakers external to the heater.
See the NEC and local codes having jurisdiction.
Additional sub-circuit fusing within the heater (built-in load fuses) may be either
mandatory or optional, and if they are chosen as optional, they may not be
recommended. The following table supplies the information necessary for the
decision to use built-in sub-circuit over-current protection.
As a general rule, built-in load fuses are rated 30 amps for circuits up to 24 amps
and 60 amps to protect one or more circuits totaling 48 amps.
Load Fuses: The minimum required sets of 60 amp fuses for proper protection (option U-1). Example of
load fusing: A single stage, three phase heater rated at 40 amps will use one set (3 fuses of 60 amps).
Stage Fuses: Mostly optional, one or more sets of fuses per stage. (Option U-2). Acutherm’s standard fuses
are 30 amps for circuits up to 24 amps, and 60 amps for circuits up to 48 amps.
Acu-Zone I & II
Electric Zone Heater
Application, Selection, &
Specification Manual
240
1 PH
208
1PH
277
1PH
347
1PH
480
3 PH
600
3PH
Heater
Rated
Amps
NEC
Electrical
Code
Internal
Load
Fusing
Mandatory
Acutherm
Recommends
Built-in
Load Fuses
Comments
12
17
13
17
40
50
0-48
NO
NO
NO
Optional Load
Fuses not
recommended –
only one power
supply
economically
justified
38
57
44
55
133
166
49-160
YES
NO
YES
Fuses Limit extent
of damage in the
terminal box in
case of a short
circuit
39 & + 58& + 45&+ 56&+ 134&+ 167&+ 161&+ YES YES YES
Mandatory in case
of short circuit
* For Higher KW capacities consult the factory regarding the most economical number of power supplies.
Total Heater KW * u
p
to . . .
Table of Load Fusin
g

Form # 70.0 IOM-001 REV 0603
Copyright Acutherm 2006 14
Electrical Components: (Step 1)
Standard Electrical Components (Step 1)
Acu-Zone I & II
Electric Zone Heater
Application, Selection, &
Specification Manual
Automatic Reset Cut-out: The automatic reset thermal cut-out is a fixed
temperature disc type safety device that opens the control circuit when the set
point is reached. It automatically resets and returns the heater to operating
condition when the overheating conditions have disappeared.
Manual Reset Cut-out: This device offers additional protection against
overheating. It is standard on heaters of 30 KW and less and those not in
excess of 300 volts. It is optional on all other heaters. This switch must be
manuall
y
reset to return the heater to its o
p
eratin
g
condition.

Form # 70.0 IOM-001 REV 0603
Copyright Acutherm 2006 15
Acu-Zone I & II
Electric Zone Heater
Application, Selection, &
S
p
ecification Manual
Magnetic Contactors: Magnetic contactors are used for stage
switching as back-up for safety devices. Approved for 250,000 cycles,
magnetic contactors are cost effective and safe. Partial break
contactors are standard on the Acu-Zone I & II units.
Transformer: A built-in control transformer is required on most
heaters (standard on Acu-Zone™ I & II) to supply 24V to the control
circuits. A Class II transformer has built-in safety protection and does not
require primary fusing. Primary and secondary fuses can be supplied
upon request.
Electronic Airflow Sensor: The electronic airflow sensor is a safety
feature that monitors the quantity if air flowing through the heater, and adjusts
the heaters capacity to match the airflow present. The sensor will shut the
heater down upon the total loss of airflow. This feature is only available on the
Acu-Zone™ I and II heaters with full SCR control. Full SCR Control is
STANDARD on the Acu-Zone™ I & II products.
SCR Controller: The SCR (Silicone Controlled Rectifier) is a
time proportioning type controller that modulates the heater and
supplies the exact amount of power to match the heat demand. It is
compatible with thermistor thermostat (ART or ADT), 0-10VDC, 4-
20ma, and 0-135ohms signals. SCR control is STANDARD on the
Acu-Zone™ Heating Units.
Standard capacities are up to 70 amps and 600V – 3 Phase.
Consult Acutherm for higher SCR capacities.
Note: SCR Controllers are position sensitive (i.e. the fins of the
heat-sink must be in a vertical position to ensure natural cooling).
Make sure to s
p
ecif
y
the installation
p
osition of the heater.
Standard Electrical Components: (Step 1)

Form # 70.0 IOM-001 REV 0603
Copyright Acutherm 2006 16
Step 2: Determine the duct dimensions, air requirements,
and mechanical options . . .
Airflow requirements for minimum velocity:
Heating coil size is very important in the efficiency and the operation of an open coil duct
heating unit. In fact, the smaller size, higher velocity electric coil will perform better,
weigh less, and ultimately cost less per KW than an otherwise identical larger coil.
Acu-Zone I & II
Electric Zone Heater
Application, Selection, &
Specification Manual
Standard Electrical Components: (Step 1)
Disconnect Switch: A built-in disconnect switch (STANDARD on the
Acu-Zone™ Heating Units) allows the heaters to disconnect individually so
maintenance and repairs can be performed. The disconnect switch is a
positive and inexpensive way to meet safety requirements, and since the
disconnect switch is factory installed electrical installation costs are further
reduced.
KW per Square
Foot Range
Comments
Less than 5 Higher cost per KW
5 to 12 Medium cost per KW
12 to 20 Low cost per KW
Over 20 Medium cost per KW
Table 1
-
KW
p
er S
q
uare Foot
Face Velocity in
Feet Per Minute
(FPM)
Comments
Less than 400 Requires de-rating
of watt density on
the elements.
Specify
proportional
control
400-2000 Most economical
range
Over 2000 Specify special
coil supports
Table 2
–
Design Velocity Table

Form # 70.0 IOM-001 REV 0603
Copyright Acutherm 2006 17
Step 2: Determine the duct dimensions, air requirements,
and mechanical options . . .
continued
Airflow requirements for minimum velocity:
Electric heating coils will generate 100% of the heating capacity regardless of the airflow
or the heating output is constant as long as the unit is energized. A drop in airflow
through an electric coil below the minimum required velocity (FPM) will increase both the
coil temperature and the temperature of the discharge air which may lead to the
overheat devices tripping out. Further, if the airflow is uneven as it passes through the
heater, then the uneven airflow across the heating element will cause “hot spots” and
premature element failure. Therefore, it is most important to select the heaters with a
KW capacity that is below 22.5 KW per square foot of duct area.
Airflow requirements for SCR Control:
The Acu-Zone™ SCR controlled heater may be considered as having an infinite number
of control stages and the heater can operate with a velocity as low as 50 FPM.
The Acu-Zone™ contains a patented proportional airflow sensor (Acu-Sensor™) that
responds to the radiant heat of the heating element which is directly affected by the
airflow quantity passing through the heater by modulating the power to the heater down,
thereby adjusting the heater capacity to accurately match the airflow available. This
feature is unique to the Acu-Zone™ heating unit - a feature that allows precisely
controlled heat upstream from the Therma-Fuser™ diffuser unit(s).
The benefits of the proportional air flow sensor are that it allows the heaters to operate
with extremely low air flow, and the heaters operate safely regardless of the duct static
pressure.
The electronic controller also allows a proportional control for the heater and is
compatible with the following input signals:
1. Variable voltage signal 0-10VDC
2. Pulse signal – 24VAC or 24VDC
Acu-Zone I & II
Electric Zone Heater
Application, Selection, &
Specification Manual
Standard Capacities Standard Dimensions
Up to 2KW @120/1/60 6”Ø through 12”Ø – 6” x 6” through 24” x 18”
Up to 5KW @ 208/1/60 6”Ø through 12”Ø – 6” x 6” through 24” x 18”
Up to 6KW @ 240/1/60 6”Ø through 12”Ø – 6” x 6” through 24” x 18”
Up to 7KW @ 277/1/60 6”Ø through 12”Ø – 6” x 6” through 24” x 18”
Up to 8KW @ 347/1/60 6”Ø through 12”Ø – 6” x 6” through 24” x 18”
Other dimensions, capacities and voltages up to 40 KW and 600V/3PH are available upon request

Form # 70.0 IOM-001 REV 0603
Copyright Acutherm 2006 18
Step 2: Determine the duct dimensions, air requirements,
and mechanical options . . .
continued
Airflow Uniformity
In order to prevent hot spots, the airflow must be uniformly distributed across the heater
area. The following figures illustrate typical heater misapplication where the airflow is not
uniform. An NEC article (see below) specifies that a heater should not be installed closer
than 4 feet downstream and 2 feet upstream from a fan outlet, an abrupt transition, an
elbow or any other kind of obstruction in the duct.
1071 NEC Article 424-59
“Means shall be provided to assure uniform and adequate airflow over the face of the
heater. Heaters installed near (within 4 feet) a fan outlet, elbows, baffle plates or other
obstruction in duct work may require turning vanes, [ressure plates or other devices in
the inlet side of the duct heater to assure an even distribution of air over the face of the
heater.”
Acu-Zone I & II
Electric Zone Heater
Application, Selection, &
Specification Manual

Form # 70.0 IOM-001 REV 0603
Copyright Acutherm 2006 19
Step 2: Determine the duct dimensions, air requirements,
and mechanical options . . .
continued
Size Limitations
Although there are virtually no limitations to the maximum size of Acutherm custom built
heaters, all CSA Listed heaters must comply with the following dimensions:
CSA listed custom heaters (Acu-Zone™ II) heaters are available in any KW rating;
however, the listing is restricted to a maximum KW density of 22.5KW per square foot of
heated area for open coil type heaters. For a quick approximation of the maximum KW
available in a particular duct size, please use the following formula:
Maximum KW = 22.5 x “W” (Inches) x “H” (inches)
144
Universal Mounting of Acu-Zone™ Heaters
The heaters are manufactured to be non-sensitive to airflow direction. The built-in high
limit cut-outs are located such that the airflow can be in either direction without impairing
the safety of the heater. The very same heater can be installed in horizontal or vertical
duct.
Acu-Zone I & II
Electric Zone Heater
Application, Selection, &
Specification Manual
Slip-in Type
Open Coil
Flanged Type
Open Coil
Minimum Duct
Width
Dimension “W”
6” 5”
Minimum Duct
Height
Dimension “H”
5” 4”
Table 3
–
Heater Size Limitations

Form # 70.0 IOM-001 REV 0603
Copyright Acutherm 2006 20
Step 2: Determine the duct dimensions, air requirements,
and mechanical options . . .
continued
Mulriple Heaters in a duct
Electric heaters are not normally designed to be used is series in a heating installation.
Very large Acu-Zone II heaters can be manufactured and shipped so they can be
simplified by using two or more units specifically designed for parallel installation. Each
section has cutouts and there are terminal blocks provided to interconnect the controls in
the field.
Clearance
Acu-Zone™ heaters are CSA and NRTL/C approved for zero clearance to combustible
material. This means that there are no distance restrictions between the section of the
duct and combustible material. Care must be taken to install the heater such that
clearance room is allowed for removal and servicing of the heater. The diagram below
shows the recommended installation clearances/
Acu-Zone I & II
Electric Zone Heater
Application, Selection, &
Specification Manual
Slip-in Type AZON II OPTIONAL Flange
Type
AZON II