Environmental Technologies EDH-4 User manual

18063 Rev E 06/17 [phone] networketi.com Environmental Technology, Inc.
We Manage Heat ®
®
MANUAL
Low Cost Air Dehydrator
MODEL EDH–4
Environmental Technology, Inc.
1850 N Sheridan Street • South Bend, IN 46628
[phone] • Fax [phone]
Toll Free [phone] • Fax [phone]
www.networketi.com • [email protected]
Installation and Operation Manual

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2 of 16 Environmental Technology, Inc.
Model EDH–4 Rev E Installation and Operation Manual
SAFETY INFORMATION AND WARNING SUMMARY
Read and become familiar with the safety information below.
Lethal Voltages Present
There are lethal voltages present inside the case of the EDH–4. Service should be per-
formed by qualified personnel only. There are no user serviceable components inside the chassis.
Ensure the EDH–4 is reliably grounded.
Abnormal Odor or Smoke
In the event of smoke or an abnormal odor, immediately interrupt power to the EDH–4. Disconnect the
unit from its power source or trip the circuit breaker controlling the outlet.
Pneumatic Pressure Hazard
Always vent the system to atmospheric pressure before servicing pneumatic components.
The air pumps in the EDH–4 Air Dehydrator are capable of generating as much as 1.2 psig (82.7 mbar).
Proper safety practice requires treating all pneumatic components with care.
Operating Temperature
Verify adequate air flow and power supply capacity is available to the EDH–4.
Ensure that the EDH–4’s maximum operating temperature of 130°F (55°C) will not be compromised by
other components in its environment.
Mounting
Before and after mounting the EDH–4, ensure that the mounting surface is stable. Mounting the EDH–4
should be such that a hazardous condition is not created due to uneven mechanical loading. Verify that
adequate air flow and power source capacity is available to the unit.
QUESTIONS AND COMMENTS
For technical help, questions or comments concerning this product or any of Environmental Technology,
Inc. products, contact the Customer Service Department between 8:00 a.m. and 5:00 p.m. Eastern Time at:
Voice [phone] (USA and Canada) or [phone] (elsewhere)
Fax [phone] (USA and Canada) or [phone] (elsewhere)
E-mail [email protected]

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Model EDH–4 Rev E Installation and Operation Manual
TABLE OF CONTENTS
SECTION PAGE
Safety Information and Warning Summary 2
Glossary 4
Returns and Replacement Parts Purchases 4
Replacement Parts List 4
Ordering Information 4
Introduction 5
Purpose of EDH–4 5
Description 5
Installation 6
Unpacking/Packing 6
Inventory List 6
Additional Equipment Required for Installation 6
Initial Inspection 6
Location of Installation 6
Mounting the EDH–4 7
Preparation and System Set-up 8
Principal Considerations 8
Power Connection 8
Pneumatic Connection 8
Operation 9
Control 9
Information Display 9
Operating Procedures 10
Automatic Operation 10
Alarm Relays 10
Emergency Procedures 10
Abnormal Smoke or Odor 10
Ruptured Feed Window 10
Technical Description 11
Electronic 11
Pneumatic 11
Theory of Operation 11
Maintenance 12
Periodic Maintenance 12
Renewing the Desiccant 12
Regenerating the Desiccant 15
Troubleshooting 15
Specifications 16

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GLOSSARY
Listed below are some important terms and their definitions.
Solar Gain
Generally occurring each day at sunrise, the time when sunlight and heat increase, resulting in a natural
corresponding rise in temperature and pressure inside a cable line. Solar gain can also occur before or after
a major weather event.
VSWR
VSWR means Voltage Standing Wave Ratio and is used to measure the amount of energy that is reflected
back into the transmitter from the antenna when the antenna is not tuned properly. Water in the transmis-
sion line will de-tune the antenna and cause a higher VSWR.
PART NUMBER DESCRIPTION
18138 Desiccant, EDH–4 Rev A
Returns and Replacement Parts Purchases
Prior to removing equipment for return, please contact ETI at [phone] for troubleshooting as-
sistance.
Before returning the unit to Environmental Technology, Inc., obtain a Return Material Authorization (RMA)
number from our Customer Service Department between 8:00 a.m. and 5:00 p.m. Eastern Time (UTC minus
five hours) at [phone] or [phone].
Replacement Parts List
ORDERING INFORMATION
ORDER NUMBER DESCRIPTION
18021 EDH–4 Rev A Low Cost Air Dehydrator
18138 Desiccant, EDH–4 Rev A
18186 Power Cord Assembly

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Model EDH–4 Rev E Installation and Operation Manual
INTRODUCTION
Please read this manual for information on the EDH–4 prior to installing, operating or servicing the unit.
Purpose of EDH–4
The EDH–4 Air Dehydrator maintains waveguides, air dielectric coaxial cable and other related compo-
nents used in earth stations, terrestrial UHF, microwave communication systems and the like. It prevents the
accumulation of moisture in dielectric lines by maintaining optimal pressure and humidity of the air in the
line. The EDH–4 enhances the reliability of a station’s signal output through supplying low pressure dry air.
The EDH–4 is intended for use in small volume C, X, Ku and Ka band applications. For larger applications,
please contact Customer Service for information on the ADH NETCOM family of automatic air dehydrators.
Unpressurized dielectric transmission lines allow the entry of moist ambient air through leaking seals,
penetrations and cracks. Consider the line passing from one environment to another, such as when enter-
ing a shelter from the antenna outside. Perhaps there is a change in existing external ambient conditions,
such as a weather front, or nightfall. These pressure and/or temperature changes in the air supply may lead
to moisture condensation within the transmission environment. This is normally the result of the ambient
temperature dropping below the dew point. Water in transmission lines causes corrosion, voltage arcing and
increased voltage standing wave ratio (VSWR). These conditions reduce system performance.
Description
The EDH–4 Air Dehydrator is an economical, manually regenerative air dehydrator for waveguide envi-
ronments. Air is pressurized by a twin head vibratory pump and then dehydrated by passing it through an
absorption unit containing a drying agent. The dried air is then delivered to the communications equipment
through a 1/4" (6.35 mm) hose barb fitting. The EDH–4 works best supplying dry air in a flowing system,
where the dehydrator completely replaces the air on a regular basis
The EDH–4 provides dry air regulated between 0.3 psig (20.7 mbar) and 0.5 psig (34.5 mbar), delivering
6.0 standard cubic feet of air per hour (2.8 l/m). Under normal conditions, the output dew point of the air is
-40°C.
Physically, the EDH–4 occupies a space 11.625" wide × 7.0" deep × 4.814" high (295.3 mm wide ×
177.8 mm deep × 122.3 mm high); three spaces of a standard relay rack.
Pressure display is user selectable to International Symbol of Units (Le Système International d’Unités, or
SI) or English customary units. Both pressure and alarm information are shown on a wide viewing angle LED
digital display. The EDH–4 makes use of two alarm relays. The first alarm relay is a renew desiccant alarm;
the second alarm relay indicates one or more alarms. The desiccant contains an orange coating which turns
white when the desiccant requires renewal.
The moisture is removed from the drying agent manually. Users must manually renew or replace the
desiccant as required. This operation is needed typically every six months to two years, depending on sys-
tem leakage and environmental conditions.
Figure 2. EDH–4
Components
Figure 1.
EDH–4’s
rechargeable
or replaceable
desiccant
Desiccant
Compartment
(viewable through
window)
Pressure/Alarm
Display
Air
Outlet
Power
Entry
Alarm Relays
(DB-9)

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INSTALLATION
Unpacking/Packing
Immediately inspect the shipping container and packing material for damage. Unpack the EDH–4, taking
care not to damage the cushioning materials. Save the shipping container and related materials until normal
operation has been established.
Inventory List
Verify that the package contains the parts listed for EDH–4 version ordered.
Additional equipment required for installation
The EDH–4 comes equipped standard with a 1/4" hose barbed fitting which accepts 1/4" ID (inside
dimension) flexible tubing. Special fittings and tubing can be purchased from ETI: contact Customer Service
for details.
Initial Inspection
Inspect the EDH–4 for electrical and mechanical damage. Contact the Customer Service Department
if you find any of the following:
• Contents incomplete or incorrect per inventory list above
• Internal or external mechanical damage
• Desiccant is white (fully charged with moisture; refer to page 13 for renewal procedure)
• Defective operation; to test effective operation:
1. Attach power to the EDH–4
2. Seal outlet (plug, thumb or kink in hose)
3. Pump stops
4. LED display reads between 30 and 50
5. Remove “seal”: LED display reads 0 (zero)
6. Replace “seal”: LED display once again reads between 30 and 50
Customer Service is available between 8:00 a.m. and 5:00 p.m. EST (UTC minus 5 hours) at (574) 233-
1202 or [phone]. In the event of shipping damage, keep packing materials for inspection by the carrier.
Location
The rack mounted EDH–4 should be located reasonably close to waveguide and power. It needs suf-
ficient clearance around it to facilitate access to power, alarm relay and pneumatic connections.
The unit requires a relay rack panel space of 19" wide × 5.25" high (482.6mm wide × 133.4" high) for
WIDE applications or 13.63" wide × 5.25" high (364.1mm wide × 133.4" high) for NARROW applications.
Because the EDH–4 seldom requires operator attention, consider locating it in the lower portion or extreme
upper portion of the relay rack.
However, on those occasions when the EDH–4 requires operator attention for desiccant recharging or
replacement, consider a location convenient for this action.
QUANTITY PART NUMBER DESCRIPTION
1 18021 EDH–4 Rev A Dehydrator
1 18063 EDH–4 Instruction Manual (this document)
EDH–4

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Model EDH–4 Rev E Installation and Operation Manual
Mounting
Install this unit in compliance with National Electrical Code (NEC) and Canadian Electrical Code (CEC)
standards, as well as all other local and applicable electrical codes for your area. Prior to beginning installa-
tion, make sure that the facility has properly sized electric service and breaker. For additional information re-
garding electrical ratings and facility power requirements, refer to the Specifications section of this manual.
The EDH–4 mounting brackets will accommodate fasteners up to 1/4 inch (6.3 mm) in diameter. The
choice of anchors and companion hardware should be appropriate for the mounting surface. At least four
anchors should be used and each should be capable of supporting a combined load of at least 5 pounds (2.4
kg). The locations of the mounting points are shown in Figure 3A, Narrow, and Figure 3B, Wide.
5.22"
132.6mm
13.63"
346.1mm
12.63"
320.7mm
2.25"
57.2mm
4.81"
122.2mm
7.00"
177.8mm
19.00"
483mm
18.00"
457mm
Figure 3A. EDH–4 Rack Dimensions: Narrow
Figure 3B.
EDH–4 Rack
Dimensions: Wide
Figure 4. EDH–4
Wall Mounting
Mounting
Points
Mounting
Points
Mounting
Points
Mounting
Points
For wall mount installation, rather than attaching the mounting
brackets at the holes along the 4.81" (122.2mm) edge (Figure 4A), align
and attach them to the holes along the 7" (177.8mm) edge (4B). Pro-
ceeding clockwise, the unit is reoriented with the mounting brackets
against its mounting surface (4C), the front display panel (with handles)
swapping positions (4D) with “eTi” front cover (4E).
The surface used for the installation should be capable of supporting
four times the weight of the unit, or about 32 pounds (14.5 kg). Be sure
to install the unit directly to a solid, stable surface. Mount the unit to the
wall (or other vertical surface) before con-
necting any other components to it.
A
E
B
CD

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Model EDH–4 Rev E Installation and Operation Manual
PREPARATION AND SYSTEM SET-UP
Principal Considerations
The EDH–4 works best supplying dry air in a flowing system, where the dehydrator completely replaces
the air on a regular basis. Consequently, the equipment being supplied dry air should be slightly leaky: that
is, continual airflow is achieved when dry air pressure from the EDH–4 is greater than the air pressure of
the environment the unit maintains. For a waveguide, this is best accomplished by slightly opening a purge
valve at the window end of the system. Likewise, air dielectric coaxial cable should be equipped with a valve
at the end opposite to where the EDH–4 pumps air, which can be set to allow a small leak. Many systems
will have sufficient normal leakage that such actions will be unnecessary.
The EDH–4 also has a check valve in its air path. A tightly sealed system may experience a pressure
increase, such as from solar gain, with a rise in ambient temperature. The EDH–4 has no way to reduce
pressure buildup. A pressure relief valve rated to protect the feed horn window is recommended to account
for this buildup.
Power Connection
The EDH–4 uses a universal (100 VAC to 240 VAC at 50/60 Hz) power supply. This eliminates the need
to set voltage during the installation or having to purchase different units for different power requirements.
The EDH–4 requires a standard outlet (North America: NEMA 5-15R) no further than 6 feet (1.8 m) from
the power entry point at the back of the unit. Consider a readily accessible disconnect device and a short
circuit and overcurrent device rated 20 amps maximum. The EDH–4 does not incorporate a power switch:
the unit will be energized as soon as power is connected to the unit. The power cord contains a ground lead.
Pneumatic Connection
The EDH–4 is supplied with a 1/4" (6.4 mm) barbed male fitting. Slip the supply tubing over the outlet
barb engaging all the ridges. The fit should be tight enough that a clamp or cable tie is not required although
its use is recommended. Special accessories are available from Customer Service, including: distribution
manifolds and a variety of pressure fittings and tubing types.
Figure 5.
EDH–4
pneumatic
connections
Tube
Assembly
Tubing T
Assembly
Final Bottle
Assembly
Note:This unit produces a slight vibration due to oscillating components. This may lead to fatigue and
possible failure of the mounting system or wall material. Please consider this when planning your installation.

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Model EDH–4 Rev E Installation and Operation Manual
OPERATION
Control
The EDH–4 makes use of a single switch called the Mode selector [MODE]. This is located just below the
PRESSURE LED display window (Figure 6). [MODE] allows the user to
• switch between English/imperial and metric units (press and hold [MODE]; metric displays “.”)
• display the percentage of desiccant remaining (quick press on and off)
• desiccant timer re-set (power off, press and hold during power up).
Information Display
The front panel’s “PRESSURE” display, a pair of seven-segment LED characters, reports pressure and
status information.
The default display reports the air pressure level passing through the unit. Pressure may be displayed in
either the default English customary units (hundredths of psig) or SI metric (mbar) units.
The display units may be switched by pressing and holding [MODE] for five (5) seconds. When units are
set to English, the unit displays “99” for 0.99 psig, the maximum displayable pressure in English custom-
ary units. The maximum displayable pressure in SI units is 99 mbar, displayed as “99.”–the decimal point
displayed to the lower right of the numerals indicates mbar mode.
To assess the Percentage Desiccant Absorption Capacity remaining, quickly press and release [MODE].
The LED displays some number “nn” where nn is 2-digit percentage of absorption capacity.“99” = 99%/
new desiccant/full capacity; “51” is 51% capacity (and so
forth); “00” = 0% left /desiccant regeneration required.
The LED display is used with [MODE] to reset the desic-
cant timer. Hold [MODE] during power-up; after LED initializa-
tion, the display reports “99”; release [MODE] to continue
normal operation. [Note: What is actually measured is sim-
ply the number of hours the compressor is running. This is
somewhat correlated with how much useful time is left to the
desiccant. The software is written with the assumption that
moist air moves through the EDH–4; if the relative humidity
is low, the desiccant may last longer.]
In the event of an alarm condition, an alarm code will be
displayed. See Table 1. If no alarm conditions exist, only the
system pressure will be displayed.
Figure 6.
PRESSURE
display window,
MODE switch
Table 1.
Alarm Codes
DISPLAY ALARM
LP Low Pressure
LE Leaky System
CD Change Desiccant
HF Verify electronic enclosure
temperature > 5°C
un EEROM unknown
(uninitialized or corrupted)
CA uncalibrated

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PIN DESCRIPTION
1 Pressure Alarm Relay Normally Closed (NC)
2 Pressure Alarm Relay Common (COM)
3 Pressure Alarm Relay Normally Open (NO)
4 Desiccant Alarm Relay Normally Closed (NC)
5 Desiccant Alarm Relay Common (COM)
6 Desiccant Alarm Relay Normally Open (NO)
OPERATING PROCEDURES
Automatic Operation
The EDH–4 will commence operation when power is applied. The unit will automatically regulate the
system pressure between 0.3 psig (20.7 mbar) and 0.5 psig (37.5 mbar).
Alarm Relays
The EDH–4 has two alarm relays; see Table 2 for pin out definition. One of the alarm relays is a pressure
alarm (labeled “PRESSURE”) and closes when any of the following conditions is met:
1.Low pressure; the system pressure falls below 0.20 psig (13.8 mbar) for 25 continuous seconds.
2.Excessive run time; the pump runs continuously for more than four hours.
3.Low temperature within electronics housing; internal temperature falls below 5°C/41°F.
The summary alarm will continue as long as any of these conditions exists. When all conditions have
been cleared, the alarm will reset. The second alarm relay closes when the renew desiccant timer signals
a need to replace or regenerate the desiccant. This alarm is reset by depressing [MODE] during power up.
Both relays close at power off.
Table 2. (near right)
Alarm Relay
Connector Pin
Assignments
Figure 7. (far right)
EDH–4 detail of
DB–9 connector
with pin numbers
EMERGENCY PROCEDURES
Abnormal Smoke or Odor
Should abnormal smoke or odor arise, immediately interrupt the power to the unit by unplugging the unit
or by tripping the breaker on the power circuit.
Ruptured Feed Window
Usually but not exclusively found in microwaves and parabolic antennas and satellite dishes, a small
horn antenna—known as the feed horn (Figure 7)—is used to share radio waves between a transmitter/
receiver/transceiver and a reflector. The opening of the feed horn, known as the feed (aperture) window, is
usually sealed to help maintain the environment the EDH–4 conditions.
An error code of “LP” or “LE” on the PRESSURE display may indicate a ruptured feed window. This
condition makes it impossible to maintain pressure in the system. Further, it is possible for water to flow into
the waveguide or coaxial connections in the event of heavy rain. If this problem occurs, you will see a drop
in output power and an increase in VSWR: IMMEDIATELY remove power from the EDH–4.
The EDH–4 will stop trying to pressurize a system if the compressor runs for four hours continuously.
After repairing the leak, restore normal operation by momentarily interrupting power to the unit.
Note: Pins 7, 8 and 9 are not used

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Model EDH–4 Rev E Installation and Operation Manual
Feed Horn
Antenna
Feed
Horn
Feed
Window
Feed
Window
Membrane
Figure 8.
Dehydrator,
waveguide,
feed horn,
antenna
signal path
TECHNICAL DESCRIPTION
Electronic
The EDH–4 makes use of a switching power supply capable of operating over a range of input voltages.
The EDH–4 processor consists of a single integrated circuit. The processor controls pump operation to
regulate system pressure, monitors electronics enclosure temperature and monitors compressor run time.
The device contains an onboard EEROM (Electrically Erasable Read-Only Memory) used to accumulate
compressor run time and to store the display mode.
Pneumatic
The pneumatic system from the pump to the unit’s outlet operates at the system pressure. The air pump
is a twin head vibratory pump. Air is drawn into the pump, compressed and delivered to the system. After
passing through the moisture absorption unit, the air passes through a check valve. The check valve pre-
vents reverse flow through the pump and ensures that pressure is maintained even in the event power is
lost. The dried air is then delivered to the outlet.
Theory of Operation
The EDH–4 consists of a control loop managing system pressure and a second loop monitoring run
time since the last desiccant replacement or regeneration. The pressure control loop is composed of the air
pump, the pressure transducer and the main microprocessor. The outlet pressure is monitored. When the
pressure drops to the low limit, the air pump is started and system pressure increases until the processor
obtains a high limit reading from the transducer. At this point, the pump is stopped and the loop is complete.
The running time for the compressor is accumulated and stored in the EEROM. When 1,000 hours have
been recorded, a Change Desiccant two-letter error code (CD) on the front panel display is issued to indicate
a need to regenerate or replace the desiccant.

PRESSURE
®
SOUTH BEND, INDIANA U.S.A.
www.networketi.com
ENVIRONMENTAL TECHNOLOGY, INC.
MODE
DEFAULT DISPLAY:
CURRENT PRESSURE
Hundredths of psi (example: 0.5 psi = “”)
or millibars (0.5 psi = 34.5 mbar = “.”)
[decimal point on right: “mbar” display mode]
Optimal Range 0.4psi ± 0.1 psi
27 mbar ± 7 mbar
MODE SELECTION
1. Percentage Desiccant
Absorption Capacity
Press MODE button.
Display = “XX” where XX is 2-digit
percentage of absorption capacity.
“”: new desiccant/full capacity
“”: desiccant replacement required
2. English or Metric Pressure Report
Press+Hold MODE button for 5 seconds.
Display changes from current setting to
alternative (psi or mbar); decimal point
indicates “mbar” mode.
3. Desiccant Timer Reset
Press+Hold MODE button at power-up.
After LED initialization, display = “”;
release the MODE button.
2-LETTER ERROR CODES
•  low pressure
•
 leaky system
•
 change desiccant
•
 heater failure
•
 EEROM unknown
uninitialized or corrupted
•
 uncalibrated
Note: for either  or  alarm, contact ETI.
If an error occurs: Display shows current pressure first,
then error condition(s). Each code displays for one
second. This display cycle repeats itself until the cause of
each error is addressed and corrected. Refer to
Operations Manual # 24932 for details.
The unit may produce pressures as high as 1.2 psig (82.7
mbar) under worst case failure. Vent the system to
atmosphere before servicing pneumatic components.
Desiccant is amorphous aluminosilica gel. Prevent dust
from entering the respiratory tract or eyes: Use proper
eye protection, suitable gloves, approved respiratory
protection and general ventilation while servicing.
EDH
TM
– 4 Rev A AIR DEHYDRATOR
EDH–4
Rev A
Circular
Tube
Feed Horn
OMT
Orthomode
Transducer
End of Waveguide
farthest from
Feed horn
TRF
Tuned Radio
Frequency
receiver
Wave Guide
Air Dehydrator
Flange
Flange
1/8" NPT Female
Pressure Inlet:
Dehydrator
Connection
1
/ 8 " NPT Female
Pressure Inlet:
Pressure Relief
or Bleed Valve
1/4" ID
UV resistant
tubing

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MAINTENANCE
Periodic Maintenance
The EDH–4 uses a granular desiccant consisting of Amorphous Alumino silica gel, coated with an orange
iron compound indicator. The silica gel granules turn white when wet, indicating the need to regenerate or
replace the desiccant. The Change Desiccant two-letter error code (CD) on the front panel display appears
when 1,000 hours have accumulated on the pump. While the desiccant requires renewal every 12 to 18
months,the exact interval depends on system operational efficiency and environmental conditions. Monthly
visual inspection of the desiccant is recommended.
Other than the desiccant, check the EDH–4 for dust and other particulates collecting in the cabinet;
remove this debris as required.
Renewing the Desiccant
Safety Note: Servicing should be performed by qualified personnel. The desiccant used in the EDH–4
Dehydrator is known as an indicating silica gel. Care should be taken to prevent the dust from entering
the respiratory tract or the eyes. Utilize proper eye protection, suitable gloves. Additionally, use approved
respiratory protection and general ventilation while servicing. The unit may produce pressures as high as
1.2 psig (82.7 mbar) under worst case failure. Vent the system to atmosphere before servicing pneumatic
components.
The desiccant bottle on the EDH–4 is accessible behind the front panel. The steps are:
1. Remove power and vent system of pressurized air
2. Remove four (4) mounting screws from front panel (Fig. 9); open front panel (note restraint cables)
3. Disconnect tubing and undo straps before completely removing the bottle from the unit
4. Lift up and remove the desiccant bottle; open bottle cap
5. Regenerate (per next section) or properly dispose of the old desiccant
Restraint
Cable
Mounting
Screws
Figure 9. Desiccant Bottle Removal – Front Display Panel
Mounting screws locations; opened front panel

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Model EDH–4 Rev E Installation and Operation Manual
Restraint
Cable
Figure 10. Desiccant Bottle Removal – Front Display Panel,
clockwise from left: Open front panel; undo straps; disconnect tubing;
ready; remove bottle; open or replace (page 15)
The desiccant bottle on the EDH–4 is accessible below the top panel. The steps are:
1. Remove power and vent system of pressurized air
2. Remove four (4) attachment screws from top panel (Fig. 11); lift and remove top panel
3. Disconnect tubing and undo straps before completely removing the bottle from the unit
4. Lift up and remove the desiccant bottle; open bottle cap
5. Regenerate (per next section) or properly dispose of the old desiccant
Attachment
Screws
Figure 11. Desiccant Bottle Removal – Front Display Panel
Mounting screws locations; opened front panel

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Figure 13. When reinstalling the desiccant bottle,
confirm that the internal air distribution channel’s
nozzle (arrows, left), marked with a black dot next
to it, is connected with the BROWN tube to the
EDH–4’s pump (photo below)
Tube reconnections may be made under control
panel wiring (lower left corner) and other tubing
Brown
tube to
Pump
viewed
from open
top panel
Reconnected
tube under
control
panel wiring
Brown
tube to
Pump
Pump
Brown
tube to
Pump
When reinserting the desiccant bottle into the EDH–4, note the mark next to the nozzle on the bottom of
the bottle. This mark indicates the nozzle connected to the pump with the brown tube. When returning the
desiccant bottle, keep the connecting tubes flexible: this may require connections under wires and other tubes.
Figure 12. Desiccant Bottle Removal – Top Panel
Top: remove the attachment screws, then the “eTi” Top Panel
Row Two: undo straps
Row Three: disconnect tubing from nozzles; remove bottle
PART NUMBER DESCRIPTION
18138 Desiccant, EDH–4 Rev A
25016 Desiccant Canister with Desiccant
Replacement Desiccant
Straps Nozzle/Tube
Connections

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Model EDH–4 Rev E Installation and Operation Manual
TROUBLESHOOTING
Troubleshoot the EDH–4 Air Dehydrator using the information below.
PROBLEM
(ALARM CONDITION) ACTION COMMENTS
Nothing works Verify the unit has power. Ensure supply power is available to the unit.
LP
Low Pressure
Disconnect feed tube from air outlet. Pump should operate continuously.
If no pump operation, check pump
electrical connections. Pump has failed or circuit board has failed.
Block the air outlet and verify whether the unit
reaches the correct operating pressure.
If continued no or low pressure with air outlet
blocked, check internal air path for leaks or
blockage.
If no blockage or leakage is detected, the pump
or the circuit board has failed.
Check external air path for leakage.
Check air flow through pump inlet filter.
LE
Leaky System
If unit pressure reads less than 0.2 psig (16.8
mbar), check internal air path for leakage.
If no blockage or leakage is detected, the pump or
the circuit board has failed.
Check external air path for leakage.
If pressure reads more than 0.5 psig (37.5
mbar), check the air path inside the unit for
blockage.
CD
Desiccant
Renewal Required
Visually inspect desiccant bottle. If the silica
particles are orange, reset the desiccant alarm
by pressing [MODE] while powering up the
unit. Note that resetting the desiccant alarm
will restart the counter to 1,000 hours. Monthly
inspections are suggested.
The [MODE] pushbutton is located just below the
PRESSURE LED display.
If the silica particles are white, renew the
desiccant. Refer to the Maintenance section of this manual.
HF
Low Temperature
Verify that the electronic enclosure
temperature is above 5°C.
Should clear alarm condition unless circuit board
has failed.
UN
Initialization Error
Reset the desiccant timer, as described for the
Cd alarm. Cycle power to see if it worked. Circuit board has failed.
CA
Calibration Error Uncalibrated. EEROM has not been set. Call Customer Service.
Regenerating the Desiccant
• Empty desiccant into clean baking dish
• Bake desiccant at 320°F (160°C) in a conventional oven for two hours, stirring every 30 minutes, or
until silica gel particles turn orange—DO NOT USE A MICROWAVE OVEN
• After silica gel particles have turned orange, remove desiccant from oven and allow desiccant to cool
to room temperature
• As soon as it reaches room temperature, desiccant should either be returned to the desiccant bottle or
placed in another airtight container to prevent its absorbing moisture from surrounding air
Fill the bottle with the new or regenerated desiccant. Reinstall the original bottle cap, confirming a tight seal.
Both adapter fitting and bottle top should be secured tightly to prevent leakage which may lead to reduced des-
iccant service life. To test, connect brown tube from its nozzle to the pump, plug output nozzle and power up:
confirm pressure does not bleed at a rate exceeding .02 psi/1.37 mbars per minute. If it does exceed this rate, this
may indicate a poor seal at the bottle cap.
Slide bottle back into compartment and reattach tubing. Replace cover with screws. To reset the Desiccant
Timer, press and hold [MODE] button during unit power-up; once display shows “99,” reinstall access cover.

18063 Rev E 06/17(800) 234-4239networketi.com
16 of 16 Environmental Technology, Inc.
Model EDH–4 Rev E Installation and Operation Manual
LIMITED WARRANTY
ETI’s two year limited warranty covering defects in workmanship and materials applies.
Contact Customer Service for complete warranty information.
DISCLAIMER
Environmental Technology, Inc. makes no representations or warranties, either expressed or implied, with respect to the contents of this publication or the
products that it describes, and specifically disclaims any implied warranties of merchantability or fitness for any particular purpose. Environmental
Technology, Inc. reserves the right to revise this publication and to make changes and improvements to the products described in this publication, without
the obligation of Environmental Technology, Inc. to notify any person or organization of such revisions, changes or improvements.
The ETI logo and We Manage Heat are registered trademarks of Environmental Technology, Inc. EDH is a trademark of Environmental Technology, Inc.
Copyright © 2014 Environmental Technology, Inc. All rights reserved.
SPECIFICATIONS
Operation
Dehydrator Type Non-Programmable, Single Can-
ister, Desiccant Dehydrator
Regeneration Method Manual Regeneration or Replacement
Regeneration Indication Desiccant Color Change and
Compressor Run Time
Outlet Dew Point -40°C (New or newly regenerated
desiccant)
to -10°C (Desiccant requiring
regeneration or replacement)
Output Pressure 0.3 - 0.5 psig (34.5 mbar)
Flow Rate 6.0 scfh (2.8 lpm)
Capacity, Standard 18 scf (510 liters)
Capacity, Max 45 scf (1,274 liters)
Discharge port Single Port: 1/8" NPT Female
(1/4" Hose Barb supplied)
Supply Voltage 100 – 240 VAC 50/60 Hz, Auto-select
Power Requirement @120 VAC: 22 watts maxi-
mum; 8.3 watts minimum
Reliability MTBF: 100,000 hours
Interface
Air Pressure Indication Digital Display (English or SI)
Data Display Pressure, Estimated Desiccant
Capacity Remaining, Error Codes
Communications Port Alarm Relay
Alarm Relay Capacity 2 Amp @ 30 VDC
Relay Connection 6-position terminal block
Enclosure
Dimensions 5.22" × 11.63" × 7.0"
(133 mm × 295 mm × 178 mm)
Weight 7.8 pounds (3.54 kg)
Mounting 19" or 13 1/2" Rack (3U space re-
quired), wall mount, shelf or table top
Environmental
Storage Temp -40°C to 60°C
Operating Temp 0°C to 55°C
ORDERING INFORMATION
Order Number Description
18021 EDH–4 Low Cost Air Dehydrator (Revision A)
25016 Replacement Desiccant Canister with Desiccant for EDH-4 (Revision A)
18138 Replacement Desiccant, 32 ounces (0.95 liters)
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