Stulz DRH-04 Instruction manual

(April, 2013)
DRH Series GEN1 Ultrasonic Humidifier Installation, Operation & Maintenance Manual
MODELS
DRH-04 DRH-08
DRH-06 DRH-16
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(April, 2013)
DRH Series GEN1 Ultrasonic Humidifier Installation, Operation & Maintenance Manual
Notice
This document contains information protected by copyright. All rights are reserved. The owner of the equipment
for which this manual is written may photocopy the contents of this manual for internal use only. No part of this
document may be photocopied, reproduced, or translated into another language for use by anyone other than the
owner of the equipment for which this manual is written without the prior written consent of Stulz Air Technology
Systems, Inc. (STULZ).
This document contains confidential and proprietary information of Stulz Air Technology Systems, Inc. Distributing
or photocopying this document for external distribution is in direct violation of U.S. copyright laws and is strictly
prohibited without the express written consent of STULZ.
Unpublished — rights reserved under the copyright laws of the United States and of other countries.
Other brands and tradenames are trademarks of their respective owners.
Copyright 2010 by Stulz Air Technology Systems, Inc.
Printed in the United States of America.
All rights reserved.
Stulz Air Technology Systems, Inc.
1572 Tilco Drive
Frederick, MD 21704
USA
MODEL NOMENCLATURE
DRH = Direct Room Humidifier
DAH = Ducted Air Humidifier
04 = Number of Transducers
06
08
16
DRH- 04- S
(Blank) = Ultra-Series Control
S = Stand Alone

(April, 2013)
DRH Series GEN1 Ultrasonic Humidifier Installation, Operation & Maintenance Manual
1.0 Introduction .......................................1-1
1.1 General......................................................1-1
1.2 Safety.........................................................1-1
1.2.1 General......................................................1-1
1.2.2 Safety Summary ........................................1-1
1.3 Product Warranty.......................................1-3
1.4 Specifications.............................................1-4
1.5 General Design..........................................1-5
1.6 Main Parts..................................................1-5
1.6.1 Ultrasonic Nebulizer Unit ...........................1-5
1.6.2 Mist Guide..................................................1-5
1.6.3 High Water Float Switch ............................1-5
1.6.4 Low Water Float Switch.............................1-5
1.6.5 Fan ............................................................1-5
1.6.6 Air Filter......................................................1-5
1.6.7 Water Fill Valve Solenoid...........................1-5
1.6.8 Water Supply Valve....................................1-5
1.6.9 Water Supply Tubing..................................1-5
1.6.10 Drain and Overflow Assembly....................1-5
1.6.11 Temperature Sensor ..................................1-5
1.6.12 Solid State relay.........................................1-6
1.6.13 Level Controller..........................................1-6
2.0 Installation .........................................2-1
2.1 Receiving the Equipment...........................2-1
2.2 Site Preparation.........................................2-1
2.3 Mounting/Placement..................................2-2
2.4 Supply and Drain Piping ...........................2-2
2.5 Main Power/Control Wiring........................2-4
3.0 Operation ...........................................3-1
3.1 Purge the Water Supply Line.....................3-1
3.2 Initial Operation Checklist..........................3-1
3.3 Procedure For Operation...........................3-1
3.4 Precautions................................................3-2
3.5 Steps for Long Term Shutdown..................3-2
4.0 Maintenance/Repairs ........................4-1
4.1 Periodic General Maintenance...................4-1
4.1.1 General......................................................4-1
4.2 Maintenance Items and Necessary Tools..4-2
TABLE OF CONTENTS
4.2.1 Air Filter......................................................4-3
4.2.2 Water Supply Filter/Strainer.......................4-3
4.2.3 Electrical Parts...........................................4-3
4.2.4 Float Switches............................................4-4
4.2.5 Water Tank.................................................4-5
4.2.6 Mist Guides................................................4-5
4.3 Troubleshooting and Repair.......................4-6
4.4 General Common Repairs/Parts
Replacement..............................................4-8
4.4.1 Preparation For Repairs.............................4-8
4.4.2 Reassembling............................................4-8
4.4.3 Replacing the Temperature Sensor ...........4-9
4.4.4 Replacing a Transducer...........................4-10
4.4.5 Replacing a Nebulizer Print Plate............4-11
4.4.6 WaterSolenoid Valves,Float Switches and
Level Control Board.................................4-11
5.0 Product Support Group....................5-1
5.1 Technical Support ......................................5-1
5.2 Obtaining Warranty Parts...........................5-1
5.3 Obtaining Spare/Replacement Parts .........5-1
6.0 Drawings............................................6-1
6.1 Layout Drawing of Humidifier.....................6-1
6.2 Electrical Circuit Diagrams.........................6-2
List of Figures
Figure 1- Installation of Humidifier .........................2-1
Figure 2- Locating the Humidifier ..........................2-2
Figure 3- Water Inlet Filter Strainer........................2-3
Figure 4- Piping Connections.................................2-3
i

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DRH Series GEN1 Ultrasonic Humidifier Installation, Operation & Maintenance Manual
1.0 INTRODUCTION
1.1 General
Recognized as a world leader, Stulz Air Technology
Systems, Inc. (STULZ) Ultrasonic Humidifiers are
designed and manufactured with the highest quality
craftsmanship using the finest materials available in
the industry. Your ultrasonic humidification system will
provide years of trouble free service if installed and
maintained in accordance with this manual. Damage
to the unit from improper installation, operation or
maintenance is not covered by the warranty.
This manual contains information for installation,
operation, maintenance, troubleshooting and repair.
STUDY the instructions contained in this manual.
They must be followed to avoid difficulties. Spare
parts are available from STULZ to ensure continu-
ous operation. Using substitute parts or bypassing
electrical components in order to continue operation
is not recommended and will VOID THE WARRANTY.
Due to technological advancements, components are
subject to change without notice.
STULZ DRH Series Ultrasonic Humidifiers are de-
signed as stand alone direct room humidifiers. Any
use beyond this is deemed to be not intended. STULZ
is not liable for any damage resulting from improper
use. The system is designed to be installed indoors
unless otherwise noted on the equipment nameplate.
1.2 Safety
1.2.1 General
Stulz Air Technology Systems, Inc. uses NOTES
along with CAUTION and WARNING symbols
throughout this manual to draw your attention to
important operational and safety information.
A bold text NOTE marks a short message in the
information to alert you to an important detail.
A bold text CAUTION safety alert appears with infor-
mation that is important for protecting your equip-
ment and performance. Be especially careful to read
and follow all cautions that apply to your application.
A bold text WARNING safety alert appears with
information that is important for protecting you from
harm and the equipment from damage. Pay very
close attention to all warnings that apply to your ap-
plication.
1-1
A safety alert symbol accompanies a general
WARNING or CAUTION safety statement.
A safety alert symbol accompanies an electrical
shock hazard WARNING or CAUTION safety state-
ment.
1.2.2 Safety Summary
The following statements are general guidelines fol-
lowed by warnings and cautions applicable through-
out the manual.
Prior to performing any installation, operation,
maintenance or troubleshooting procedure read and
understand all instructions, recommendations and
guidelines contained within this manual.
WARNING
High voltage is used in the operation of this
equipment. Death on contact may result if
personnel fail to observe safety precau-
tions.
CAUTION
This unit must be installed according to local
and national electric codes.
CAUTION
All maintenance and/or repairs must be per-
formed by a qualified technician. All person-
nel working on or near equipment should be
familiar with hazards associated with electrical
maintenance.
CAUTION
Always turn off the main power and unplug the
unit before beginning work on the equipment.
NOTE
Wiring terminations may become loose during
transitof the equipmenttherefore; verify allwir-
ing terminations are secure prior to operation.
NOTE
Do not attempt to make repairs without the
proper tools.

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DRH Series GEN1 Ultrasonic Humidifier Installation, Operation & Maintenance Manual
1-2
NOTE
STULZ offers no warranty protection on
humidification systems using controls that are
not provided by STULZ.
CAUTION
It is essential that De-ionized (DI) or Reverse
Osmosis (RO) water be used as the supply
water source to maintain full warranty cover-
age. The use of untreated water will VOID
THE WARRANTY.
CAUTION
Use only non-corrosive stainless steel or poly
tubing rated for use with DI water to supply
the humidifier.
CAUTION
Provide a drain with an air gap per local and
national plumbing codes.
CAUTION
Never block the mist outlet or the opening of
the air inlet. The humidifier may be filled with
the condensed mist and electrical shorts may
result.
CAUTION
Observe the unit for water leakage. A
short circuit could occur if the humidifier is
splashed with water while operating.
CAUTION
Never attempt to remove the mist guide cover
and/or the mist blow tubes while the humidifi-
er is operating, or electrical shorts may result.
CAUTION
If there is a risk of supply water freezing, pipe
insulation should be provided.
CAUTION
Never apply power when the humidifier is
overturned or upside down. Damage to the
ultrasonic nebulizer unit or transducer may
result.
CAUTION
Never drop the humidifier or apply hard shock
to it. It may damage internal parts.
CAUTION
Drain the water in the tank for sanitary rea-
sons when humidifier is turned is off for more
than 3 days.
Ultrasonic Humidifier- Model DRH-06

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DRH Series GEN1 Ultrasonic Humidifier Installation, Operation & Maintenance Manual
1-3
1.3 Product Warranty
STULZ offers a standard two year limited warranty as stated below:
Conditions for Maintaining Warranty Coverage:
1) De-ionized (DI) or Reverse Osmosis (RO) water is used as the supply water for the humidifier.
2) STULZ provided controls are used with the humidification system.
3) Input voltage to the humidifier does not exceed 51VDC.
2-Year Standard Limited Warranty:
Stulz Air Technology Systems, Inc., warrants to the original buyer of its products that the
goods are free from defects in material and workmanship. Stulz Air Technology Systems,
Inc.’s obligation under this warranty is to repair or replace, at its option, free of charge to the
customer, any part or parts which are determined by StulzAir Technology Systems Inc. to be
defective for a period of 24 months from date of shipment when a completed start-up form
has been submitted to Stulz Air Technology Systems, Inc. within 90 days from shipment. In
theeventthatacompletedstart-up form is not received byStulzAirTechnologySystems,Inc.
within90 days from shipment, the company’sobligation will be for a periodof 12 months from
date of shipment. Parts repaired or replaced under this warranty are shipped FOB Factory,
and warranted for the balance of the original warranty period or for 90 days from the date of
installation, whichever is greater.
Stulz Air Technology Systems, Inc.’s warranty does not cover failures caused by improper
installation, abuse, misuse, misapplication, improper or lack of maintenance, negligence,
accident, normal deterioration (including wear and tear), or the use of improper parts or
improper repair.
Purchaser’s remedies are limited to replacement or repair of non-conforming materials in ac-
cordance with the written warranty. This warranty does not include costs for transportation,
costs for removal or reinstallation of equipment or labor for repairs or replacement made in
the field.
If any sample was shown to the buyer, such sample was used merely to illustrate the general
type and quality of the product, and not to represent that the equipment would necessarily
conform to the sample.
This is the only warranty given by the seller, and such warranty is only given to buyers for
commercial or industrial purposes. This warranty is not enforceable until the invoice(s) is
paid in full.
THEFOREGOINGSHALLCONSTITUTESTULZ’SENTIRELIABILITYANDYOUREXCLU-
SIVE REMEDY. IN NO EVENT SHALL STULZ BE LIABLE FOR ANY DIRECT, INDIRECT,
SPECIAL, INCIDENTAL, CONSEQUENTIAL, OR EXEMPLARY DAMAGES, INCLUDING
LOST PROFITS (EVEN IF ADVISED OF THE POSSIBILITY THEREOF) ARISING IN ANY
WAY OUT OFTHE INSTALLATION, USE OR MAINTENANCE OF THE EQUIPMENT. THIS
WARRANTYIS IN LIEUOFALLOTHER WARRANTIES,EXPRESS OR IMPLIED,INCLUD-
INGWARRANTIESOFMERCHANTABILITYORFITNESSFORAPARTICULARPURPOSE.

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

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DRH Series GEN1 Ultrasonic Humidifier Installation, Operation & Maintenance Manual
1-4
1.4 Specifications
Type DRH Series Ultrasonic Humidifier
Model DRH-04 DRH-06 DRH-08 DRH-16
Nebulizing capacity (lb/h) 4.4 6.6 8.8 17.6
Qty. of Ultrasonic nebulizers/unit 4 6 8 16
Power source 48VDC
Rated power consumption (W) 145 220 285 565
Weight (lb) 19.8 24.3 30.9 50.7
Electrical Characteristics
Allowable voltage range 47-51VDC
Insulation resistance 100 M.Ohms or more (excluding solid-state components).
Dielectric voltage withstand Operational when 1500VAC is applied for 1 minute (excluding solid-state components).
Operating conditions
Ambient working conditions 34 to 122°F; 90%RH or less.
Water supply quality DI or RO water. Water conductance <5 microsiemens purity.
Water supply pressure 30 to 60 psi
Water supply temperature 40°F to 104°F
Parts to be provided by user:
DI or RO supply water, Water supply valve, Water supply tubing (1/4” stainless steel or poly tubing rated for DI water),
power supply wiring and control wiring to the control box.
Notes: 1) Calcium, magnesium or other agents that may be contained in the supply water are atomized into
the air together with the mist and may form white powders after the water has evaporated. To avoid
this, always use DI or RO supply water.
2) The nebulizing capacity of the transducer in the ultrasonic nebulizer unit decreases gradually with
use. It should usually be exchanged after about 10,000 to 15,000 hours of operation, (depending
on water quality and suitable voltage), although the unit may continue to run as long as it’s effective
capacity meets the particular requirements.
3) To ensure full warranty coverage, the input voltage to the humidifier must not exceed 51VDC. If the
input voltage exceeds 51VDC, damage to the transducers and print plates will result.

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DRH Series GEN1 Ultrasonic Humidifier Installation, Operation & Maintenance Manual
1-5
1.5 General Design
The DRH Ultrasonic Humidifier directly atomizes water, producing a fine mist. The humidifier incorporates
high frequency nebulizers to produce ultrasonic waves, a fan to propel the mist out, and an automatic water
supply mechanism to maintain the supply water at a constant level. When conducting routine maintenance, it is
important to clean the air filter and water tank because it significantly affects the humidifying capacity and life of
the ultrasonic nebulizers.
1.6 Main Parts
1.6.1 Ultrasonic Nebulizer Unit
This consists of a modular assembly located in the
bottom of the water tank incorporating a 1.6Mhz
power oscillator on and a piezoelectric transducer.
The transducer vibrates at that frequency, developing
ultrasonic columnar waves in the water and
producing a fine mist above that column.
1.6.2 Mist Guide
The mist guide carries the mist off the top of the
columnar wave and directs it up and out of the
humidifier.
1.6.3 High Water Float Switch
For maximum atomization, it is essential the water
level in the tank be constantly maintained. The High
Water Float Switch is an input to the Level Controller.
It is open when the water level is below the optimal
level and is closed when the water level reaches the
maximum level.
1.6.4 Low Water Float Switch
Operating the humidifier when the water level is
below the top of the transducers will damage the Ul-
trasonic Nebulizer Unit. The Low Water Float Switch
is an input to the Level Controller. It is open when
the water level is near an unsafe level and is closed
when the water level is at a minimal level.
1.6.5 Fan
The 24VDC fan or fans both lightly pressurizes the air
above the water to provide a path for the mist to pass
through the Mist Tubes and provides a sheet of air to
carry the mist away from the humidifier into the room.
The fan is controlled by the Level Controller.
1.6.6 Air Filter
The Air Filter removes coarse dust from the air and
prevents the humidifier water tank from becoming
dirty which would affect the mist output.
1.6.7 Water Fill Valve Solenoid
The Water Fill Valve Solenoid is a 24VDC solenoid
that allows water from the water supply to enter into
the tank when energized by the Level Controller.
There is an orifice to restrict the flow of water.
1.6.8 Water Supply Valve
(To be provided by the user)
A valve must be installed upstream from the humidi-
fier for service and maintenance. The valve must be
rated for DI water.
1.6.9 Water Supply Tubing
(To be provided by the user)
Water supply tubing must be provided to connect the
water supply to the water filter/strainer in the back
of the unit. The filter/strainer is equipped with a ¼”
compression fitting. Utilize ¼” stainless steel or poly
tubing rated for use with DI water.
1.6.10 Drain and Overflow Assembly
The Drain and Overflow Assembly contains a 24
VDC drain solenoid valve, an overflow pipe and a
drain outlet. The drain valve solenoid is controlled by
the Level Controller to drain water from the tank via
the drain outlet. If the water level in the tank exceeds
the height of the overflow pipe, the excess water is
diverted to the drain outlet.
1.6.11 Temperature Sensor
The temperature sensor monitors the temperature
of the tank and is read by the Level Controller which
prevents overheating and freeze protection

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DRH Series GEN1 Ultrasonic Humidifier Installation, Operation & Maintenance Manual
1.6.12 Solid State Relay
The 48 VDC operating voltage for the Ultrasonic
Nebulizer Units is switched on and off by a solid state
DC relay controlled by the Level Controller.
1.6.13 Level Controller
The Level Controller is a microprocessor based
device located in the electric box that receives inputs
from sensors and other inputs and in turn controls the
valves, fan and Ultrasonic Nebulizer Units. It consists
of a DC-DC power supply to convert the 48VDC
to 24VDC for the fans and solenoids and a further
reduction to 5VDC for the microprocessor, sensors,
power switches and either a Modbus interface to
communicate with the Ultra-Series Controller or
a simple standalone input interface depending on
which model humidifier was purchased. The 48
VDC must be present at all times to allow the Level
Controller microprocessor to monitor the inputs and
control the outputs.
The microprocessor monitors the on/off command
from either the Modbus or the input dry contact
(depending on which model was purchased). If
commanded on, the microprocessor checks the Low
Water Float Switch and the High Water Float Switch.
If the water is too low, the microprocessor turns on
the Water Fill Valve Solenoid and monitors the Float
Switches. When the water level is above the low
water level, the fan is turned on. When the water
level is above the high water level, the Water Fill
Valve Solenoid is turned off and the Solid State Relay
is turned on. When the water level falls below the
high water level, the microprocessor turns the Water
Fill Valve Solenoid on again to maintain optimal
water level. When the on/off command is removed,
the Solid State Relay is turned off and, after a few
seconds time delay to eliminate the remaining mist
from the humidifier, the Fan is turned off.
Proportional control is accomplished by the
microprocessor monitoring the proportional signal
from the Modbus or proportional input (depending on
which model was purchased). When the proportional
signal is greater than 10% of the maximum input, the
microprocessor will turn the Solid State Relay on and
off in a pulse-width modulation control. The period
of the pulse width is 1 second. For 10% control, the
Solid State Relay is turned on for 0.1 second and off
for 0.9 second. The on time increases as the input
approaches 100%. At 100%, the Solid State Relay is
on continuously.
Safety control is built into the microprocessor. The
voltage applied to the transducer affects the amount
of mist produced. Too high a voltage can cause
damage to the transducer and too low a voltage
prevents mist from being formed. The microprocessor
monitors the 48 VDC to be within a range of voltages.
If the voltage is out of range, the microprocessor will
not energize the Solid State Relay.
If the temperature of the tank rises too high, the
microprocessor turns off the Solid State Relay.
If the temperature approaches freezing, the
microprocessor turns off the Solid State Relay and
the fan, and then drains the tank to prevent damage
from freezing water. When the temperature returns to
a safe level, normal operation is resumed.
A low level alarm is annunciated when the
microprocessor sees the Low Level Float Switch
indicate low water after the tank has been filled. A
fill alarm is annunciated when the High Water Float
Switch does not indicate the water level has been
achieved after a predetermined amount of time. A
transducer alarm is annunciated if the transducers
have been energized and no water is used in a
predetermined time (indicating no transducer is
functioning). For the Modbus version of the Level
Controller, failure to receive commands on the
Modbus within a predetermined amount of time will
annunciate a communications alarm.
The Level Controller has an LED that displays, via
blinking, any alarm condition that occurred after
power up. Each alarm is associated with a number of
blinks, followed by a pause, and then the next alarm
is displayed. To view the LED, the Mist Guide Cover
must be removed and the electrical access cover
removed. The LED blink pattern for each alarm is:
Number
of Blinks Alarm Condition
1 Low Voltage
2 High Voltage
3 Freeze
4 High Temperature
5 Low Water
6 Fill Alarm
7 Communications
8 Transducer
1-6

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DRH Series GEN1 Ultrasonic Humidifier Installation, Operation & Maintenance Manual
2-1
2.0 INSTALLATION
2.1 Receiving the Equipment
Your Ultrasonic humidifier has been tested and inspected prior to shipment. To ensure that your equipment has
been received in excellent condition, make a visual inspection of the equipment immediately upon delivery.
Carefully remove the shipping container and all protective packaging. Open the box and thoroughly inspect
the unit for any signs of transit-incurred damage. If there is shipping damage, it must be noted on the freight
carrier’s delivery forms BEFORE signing for the equipment.Any freight claims MUST be done through the
freight carrier. STULZ ships all equipment FOB factory. STULZ is not liable for any equipment damage while
in transit. STULZ can assist in the claim filing process with the freight carrier. Should any such damage be
present, notify the STULZ Product Support Group prior to attempting any repairs. Refer to Section 5.0 of this
manual for instructions.
Check the equipment against the packing slip to see if the shipment is complete. Report all discrepancies to the
appropriate authority.
Contents of Package:
1. Humidifier
2. Supply water filter/strainer.
3. Installation, Operation and Maintenance manual.
Avoid dropping or jarring the unit to prevent damage to the internal parts. The unit should always be stored in a
dry location prior to installation.
A Data Package has been sent with your unit. It contains this manual, system drawings, applicable MSDS’s and
other applicable instructions based on the configuration and options selected for your unit. The data package has
been placed in your unit in a clear plastic bag. These documents need to be kept with the unit for future reference.
2.2 Site Preparation
STULZ ultrasonic humidifiers are designed with easy service access in mind. Install the unit in a secure location
where it cannot be tampered with and the power switch cannot be inadvertently turned off. Allow access to the
unit for routine operation, servicing and for necessary maintenance. Position the humidifier in such a way that
the unit can be easily removed for future inspection and maintenance. Refer to the installation drawing provided
with your unit for the dimensions of the humidifier.
NOTE
Working clearance requirements need to be established prior to mounting the unit. Refer to local and
national electrical codes.
When selecting the installation location, atten-
tion should be paid to the air flow in the room
so that the atomized mist can be uniformly
diffused throughout the room. If any obstacle
exists in front of the atomized mist outlet, the
mist will be condensed on the obstacle to
form water droplets.
Figure 1- Installation of Humidifier

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DRH Series GEN1 Ultrasonic Humidifier Installation, Operation & Maintenance Manual
2-2
The humidifier must be installed horizontally and level to prevent the float switches from giving a false reading.
Prepare hanging bolts for installing from the ceiling or brackets for wall mounting (see Figure 1). The distance
from the humidifier to the ceiling should be a minimum of 18” and the distance to the wall must be 3” or more.
For the installation mounting base dimensions, see the installation drawing provided with your unit.
Figure 2- Locating the Humidifier
NOTE
Humidity control can only be achieved in a sealed room or if the room has vapor barriers installed. It is
recommended that walls, ceilings and floors be sealed to prevent migration of humidity.
2.3 Mounting/Placement
STULZ ultrasonic humidifiers are designed for mounting to a flat surface. Ensure the base is capable of support-
ing the weight of the unit. Weight estimates can be found on the installation drawing provided with your unit.
Secure the unit with fasteners (field supplied by others), so that it will not move during operation. Ensure the front
edge of the humidifier is not hanging over the edge of the support bracket.
2.4 Supply and Drain Piping
The humidifier will require a field installed water supply line and drain line. Refer to the piping diagram provided
with your unit for details. For the water supply, use DI or RO water. The water supply to the humidifier cannot
be taken directly from the public water service. Untreated supply water will leave a residue in the conditioned
space where “white powder” is produced after evaporation from the calcium or magnesium which is dissolved in
the water. In cases where water quality, especially “residue from evaporation”, “pH”, “total hardness” and “water
conductivity” exceeds or is outside the range of standard, routine maintenance intervals to ensure continuous
operation will be more frequent than usual. Also, the operating life of the transducers and print plates will be
significantly reduced.

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DRH Series GEN1 Ultrasonic Humidifier Installation, Operation & Maintenance Manual
2-3
CAUTION
It is essential that DI or RO water be used as the supply water source to maintain warranty coverage. The
use of untreated water will VOID THE WARRANTY.
NOTE
Thewatersupplypipingmustbenon-corrosivestainlesssteelorpolytubingratedforusewithde-ionizedwater.
Prepare the water supply piping. The water supply piping should be equipped with a water supply valve for
maintenance purposes (user provided) at a place as close as possible to the humidifier. The valve must be
rated for use with DI water. After the water supply valve is installed, flushing should be done by supplying water
(see Section 3.1, “Purge the Water Line”). This is a necessary step to prevent chips and oil in the piping from
entering the humidifier.
Locate the water filter/strainer assembly (shipped loose) and apply teflon tape to the threaded end. Ensure the
tape does not extend over the first two threads on the fitting (to prevent any pieces of tape from entering the
water stream). Hand screw the filter/strainer assembly into the water inlet fitting in the side of the humidifier until
some resistance is felt. Then using an open end wrench on the reducer fitting, screw the assembly 1 full turn to
fully tighten it. DO NOT tighten the filter/strainer by grasping the plastic body.
The filter/strainer is equipped with a ¼” compression fitting (see Figure 3). Connect the water supply piping to
the humidifier by means of a 1/4” stainless steel or poly tubing (user provided). Use two adjustable wrenches to
tighten the connection on the humidifier. (Tightening torque: approximately 90 in/lbs). If there is a risk that the
water supply piping could freeze, wrap the piping with insulating material..
Figure 3- Water Inlet Filter/Strainer
FLOW
¼ Compression
Fitting
Figure 4- Piping Connections
Humidifier
To Drain
(Include Air Gap)
Drain Line
Water Supply Piping
Water Supply Valve
Water Supply
Filter/Strainer
Provided By User
A drain line rated for use with DI water must be provided from the I/8” NPT water tank drain stub in the side
of the unit. Connect the drain line to the stub so that overflowing water can be directed into a drain pan or an
appropriate place such as an open building drain with an air gap per local and national plumbing codes. The
drain line must meet local and national plumbing codes, be sloped downward and away from the humidifier,
include and air gap, and the end should not be obstructed.

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2.5 Main Power And Control Wiring
For wiring, refer to the electrical drawing supplied with your unit to determine the total number of inter-
connecting conductors required for your system and for the proper wire terminations.
For internal wiring of the humidifier, see the “Electrical Circuit Diagrams”, Section 6.2.
NOTE
Wiringterminationsmaybecomelooseduringtransitoftheequipmenttherefore,verifyall wiring terminations
are secure prior to operation.
Verify that the main power supply to the control box coincides with the voltage, phase and frequency information
specified on the nameplate. The nameplate also provides the full load amps (FLA), the current that the unit
will draw under full design load, the minimum circuit ampacity (MCA) for wire sizing, and the maximum fuse
size (MFS) for circuit protection. The power source must be provided with a circuit breaker for safety. Ensure a
ground is connected to the unit. The humidifier is rated to operate with a nominal input of 48VDC. To maintain
warranty coverage, never allow the humidifier input voltage to exceed 51 volts as damage will occur to the
transducers and print plates.
2.5.1 Wire Sizing From Control Box to Humidifiers
The following table indicates the correct electrical wire sizing from the control panel to the humidifiers for three
different distances. All wire sizes listed are for stranded, THHN or NTW wire only. Do not use solid conductor
wire. For distances over 75 feet please consult the factory.
Model
Humidifier Power (Watts) Current (Amps) Wire Size (AWG) # of Wires
25 ft. 50 ft 75 ft. Prop. On/Off
DRH-04 145 3.2 16 16 14 2 2
DRH-06 220 4.6 16 16 14 2 2
DRH-08 285 6.0 16 14 12 2 2
DRH-16 565 11.8 16 14 12 2 2
NOTE: The table above reflects the correct electrical wire sizing from the control panel to the humidifiers for
three different lengths. Wire sizes listed are for stranded wire only (either THHN or NTW). Do not use solid
conductor wire. Do not exceed 75 ft. maximum distance.
In addition to the above power wires, humidifiers controlled by the Ultra-Series controller require a 3 conductor
shielded 22 AWG Modbus cable, daisy chained from the humidifier(s) to the controller. The Modbus cable is not
to exceed 1000 feet total length. A termination resister must be installed on the last humidifier as shown in the
electrical drawing provided with your unit.
CAUTION
The termination resistor is to be placed only on the last unit in the Modbus string.
CAUTION
It is important to note that the power supply provided with the equipment is sized and selected based upon
the expected load for the unit. Do not connect any additional loads to the control power supply. Connecting
additional loads may result in overloading which will cause the power supply to shut down.

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3.0 OPERATION
3.1 Purge the Water Line
Before operating the unit, metal shavings or debris that may form during the installation process must be
flushed from the water supply piping. Perform the following steps before allowing water to flow into the
humidifier:
1. Ensure the main disconnect switch from the control box is set to “Off” for safety.
2. With the water supply valve closed, disconnect the supply tubing from the filter strainer in the side of the unit.
3. Open the supply valve and flush the tubing into a bucket or building drain for about 30 seconds.
4. After the water line is purged, close the valve and reconnect the supply line to the inlet filter/strainer.
3.2 Initial Operation Checklist
For new installations, ensure the unit is ready to operate by going through the following checklist prior to start-up:
1. The humidifier is installed horizontally and level.
2. No obstacle is within 15 feet in front of the atomizing direction.
3. The electrical wiring is correctly connected.
4. De-ionized or reverse osmosis water supply is used.
5. The water supply piping and overflow piping are correctly connected and secured.
6. All parts are correctly installed.
After the above items are checked, operation may begin.
3.3 Procedure for Operation
1. Turn the main power source switch on the control box to the “On” position.
2. Open the water supply valve allowing water to flow to the humidifier.
3. Perform a manual drain cycle to flush any particulates from the tank utilizing the system controller (see
STULZ Ultra-Series controller IOM manual #OUU0078, Section 5.5.1.2).
4. Set the humidity setpoint to the desired humidity level.
5. When power is supplied to the humidifier and there is a demand for humidification, water flows into the unit.
When the water in the tank reaches the required level, the ultrasonic nebulizers will start producing mist.
6. If the unit does not start operating, increase the humidity setpoint to create a demand for humidification.
7. During operation, the humidifier starts and stops by means of a signal from the control box.
8. The water level in the water tank is maintained by the level controller.
9. If the water level in the tank falls below the safety level for any reason during operation, power to the
ultrasonic nebulizers is cut off by the level controller.
After operation is started, check the following items on a regular basis:
Atomized mist is visible through all the mist blow tubes.
Check the humidifier parts, overflow pipe and other piping for signs of leaking water.
Changethe humidity setpoint to ensure the controlbox is interconnected properly and that it controls the
operation of the humidifier.
Check to see that the mist diffusion is good and that objects in the room or any obstacle are not directly
exposed to the mist.

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3.4 Precautions
Do not remove the air filter at the bottom of the humidifier during operation.
Do not block the outlet of the mist blow tubes. It could cause a failure if the mist flow is reversed.
Drain the water from the water tank for sanitary reasons if the unit is turned off for more than 3 days.
3.5 Steps for Long Term Shutdown
If the humidifier is not signalled to turn “On” for a period of three days, the level control board will automatically
signal the humidifier to operate a drain cycle.
When operation is stopped for a long time (one week or longer), the following steps may be performed. Also,
refer to Section 4.1, “Periodic General Maintenance”.
Close the water supply valve.
Drain the water tank.
Turn the main switch on the control box to “Off”.
Check and clean the water tank interior and the air filter.
To restart operation after a long-term shutdown, see the previous Section 3-3, “Procedure for Operation”.

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4.0 MAINTENANCE/REPAIRS
4.1 Periodic General Maintenance
Systematic, preventive maintenance of the humidifier is recommended for optimum system performance. Rou-
tine periodic maintenance should include, but is not limited to the following:
Tightening electrical connections.
Cleaning, inspecting the unit’s components visually.
Checking the level of water and ensuring no leaks are present.
A system should be established to record any problems, defects or deficiencies noted by operators and discov-
ered during maintenance inspections, together with the actions taken. For assistance, contact STULZ Product
Support (see Section 5.0). Ensure adherence to all safety precautions while performing any type of mainte-
nance.
4.1.1 General
Before the maintenance inspection and repairs are done, be sure to set the control box power switch to “Off”
and close the water supply valve.
WARNING
Turn off power to the unit unless you are performing tests that require power. With power and controls
energized, the unit could begin operating automatically at any time.
Solid scaffolding must be provided for working in high places.
Care must be taken avoid injury by sharp edges of the sheet metal, etc.
CAUTION
The transducer is a very delicate part. When the water tank interior is cleaned, special care must be taken
to ensure the transducer is not scratched on the surface with a screwdriver, etc.
Do not supply power to the ultrasonic nebulizer units while the transducer lead wires (yellow and orange)
are removed.
Proper tools must be used. Excessive tightening or insufficient tightening may cause failure.
When performing maintenance or repairs, care must be taken to ensure small parts such as screws will
not be lost.
Testing insulation resistance and dielectric withstand voltage should be avoided because the humidifier
incorporates sensitive electronic parts.
When parts are replaced, genuine STULZ parts must be used. Contact STULZ Product Support for
assistance.

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4.2 Maintenance Items and Necessary Tools
Replacing transducer. After about 10,000 to 15,000
hours of operation.
Sect. 4.4.3
Replacing nebulizer
print plate.
If damaged or upon failure.
Replacing water supply
solenoid valve.
Replacing float switches.
Replacing printed circuit
board.
Sect. 4.4.6
Adjustable wrenches (2)
Phillips screwdriver
5.5 mm Nut driver
Soft cleaning cloth
Small brush
Diagonal wire cutter
Item Cycle Description Necessary Tools
Phillips screwdriverAir filter cleaning. About once a week depending
on the extent of contamination.
The interval should be short-
ened if environmental condi-
tions are particularly dusty.
Sect. 4.2.1
Check water tank
interior, mist blow tubes
and electrical parts.
Once a month or as required
if environment is dusty or
water supply quality is poor.
Sect. 4.2.3
Routine Maintenance
Replacing Parts
If damaged or upon failure.
Also recommended when
replacing transducer.
Replacing temperature
sensor. If damaged or upon failure.
Sect. 4.4.4
Sect. 4.4.5
Clean/replace water
supply filter/strainer
element.
Once every 3 months or as
required if water supply qual-
ity is poor.
Sect. 4.2.2

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4.2.1 Air Filter
1) Stop the humidifier.
2) Loosen and remove the filter case mounting screws (2 Pcs.)
at the lower front of the humidifier. Photo 1
3) Pull out the filter case. Photo 2
4) Wash the filter media with clean water.
5) Lightly shake off excess water and dry it well in the shade.
6) When the filter is dried, put it back in the filter case, install the
stopper and install the filter case in the humidifier.
7) If the filter is seriously clogged and cannot be cleaned by
washing with water, or if it is seriously deteriorated, it should be
replaced with a new one.
4.2.2 Water Supply Filter/Strainer
1) Stop the humidifier, set the control box disconnect switch to
“Off” and close the water supply valve.
2) Loosen the bowl on the filter/strainer assembly and remove it.
Photo 3
3) Remove the element and rinse the filter and the inside of the
bowl with DI water.
4) Inspect the filter element. If dirty, replace the element with a
new one.
5) Re-install the filter element and bowl on the filter/strainer.
4.2.3 Electrical Parts
1) Stop the humidifier, set the control box disconnect switch to
“Off” and close the water supply valve.
2) Drain the water tank.
Note
Be careful not to splash water onto the electrical parts.
3) Remove the mist guide cover from the top of the humidifier.
4) Remove the screws (4 Pcs.) holding the electrical box access
cover. Photo 4
5) Remove the electrical box access cover. Photo 5
Inspect the interior and check the following:
No water leakage from the solenoid valve joint.
No damage to electrical wires or cables.
No abnormality of parts.
2
1
4
5
3

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6) Remove the terminal connectors (3 Ea.) from the sides of the
level control board. Photo 6
7) Slide the board out and ensure there is no discoloration,
deformation or deterioration of the printed circuit. Photo 7
If any defects are found with the electrical parts, take
necessary steps referring to Sect. 4.4 “Common Repairs/Parts
Replacement”.
4.2.4 Float Switches
1) Loosen and remove the float panel mounting screws (2 Pcs.)
Photo 8
Note
Don’t let the screws drop into the tank.
2) Lift the float panel out and turn it over. Photo 9
3) Check for contamination. Manually operate the two float
switches ensuring they raise and lower smoothly. Clean any
build-up from the two float switches with a small brush.
Photo 10
Note
Be careful not to remove the float portion from the stem.
4) If no defects are found through the above inspection, re-
assemble by reversing the above procedure.
Note
Whenassembling,becarefulnottopinchthewiresbetween
the sheet metal.
9
8
7
6
10

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4.2.5 Water Tank
1) Loosen the fan casing mounting screws (4 Pcs.) on the sides
of the humidifier and slide it up from the base. Photo 11
2) Turn the fan casing on it’s side. Remove the screw inside the
casing (1 Pcs.) holding the air flow guide (water tank cover).
Photo 12
3) Return the fan casing to an upright position and remove
the screws (2 Pcs.) holding the airflow guide on top of the
humidifier. Remove the air flow guide. Photo 13
4) Check the water tank interior for contamination. Wipe and
clean the water tank interior and clean the surface of the
transducers, etc. in the water tank by wiping with a soft, oil free
cleaning cloth. Photo 14
Note
Be careful not to scratch the surface of the transducers.
4.2.6 Mist Guides
1) Rotate and remove the mist guide tubes from the air flow
guide (water tank cover).
Photo 15 & 16
2) Clean the mist blow tubes with clean water.
Note
It is essential that the mist outlet and its surrounding area
are free from foreign material.
Note
Be careful not to damage the rubber ring portion of the
mist outlet.
3) Re-assemble by reversing the above procedure.
15
16
4-5
12
13 14