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Bulletin 527-G
Installation and Maintenance
Series EHU-700 Humidifiers
Please Read And Save These Instructions
The Armstrong Series EHU-700 humidifier is an electronically controlled, non-pressurized steam-generating
humidifier, with its vapor discharged into a duct of an air-handling system or through a fan package. The
Armstrong Series EHU-700 consists of three models: The EHU-701, 703 and 704. The maximum capacity
of the series is 240 Ibs/hr.
To allow the Series EHU-700 humidifier to function to its full capability, be certain to install it in accordance
with the following Armstrong recommendations. For further assistance, please contact your local Armstrong
representative for the video tape, "Armstrong Series EHU-700 Humidifiers: Installation, Operation and
Maintenance".
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Summary of Contents for Armstrong EHU-700 Series
- Page 1 Bulletin 527-G Installation and Maintenance Series EHU-700 Humidifiers Please Read And Save These Instructions The Armstrong Series EHU-700 humidifier is an electronically controlled, non-pressurized steam-generating humidifier, with its vapor discharged into a duct of an air-handling system or through a fan package. The Armstrong Series EHU-700 consists of three models: The EHU-701, 703 and 704.
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Page 2: Warnings
HIGH VOLTAGES EXIST INSIDE THE HUMIDIFIER To protect yourself and others from accidental shocks: 1. Keep the humidifier locked during normal operation and store the key in a safe location away from the humidifier. 2. ALWAYS DISCONNECT THE POWER SUPPLY AT THE CIRCUIT BREAKER OR SAFETY SWITCH BEFORE OPENING ANY COVERS! 3. -
Page 3: Table Of Contents
SECTION 1: PREPARATION AND INSTALLATION WARNINGS... PRE-INSTALLATION... Check shipment... Check local codes... Site selection... INSTALLATION... Mounting... Electrical wiring... Water supply... Drain connection... Steam dispersion tube... Control wiring... High limit humidistat... Airflow switch... Audible alarm... Wiring diagram... SECTION 2: START-UP AND OPERATION DISPLAY (INSTRUMENT) PANEL... -
Page 4: Pre-Installation
PRE-INSTALLATION 1) CHECK SHIPMENT A claim should be filed with the transportation company (and reported to Armstrong) if any items are missing or damaged. Your shipment will arrive in two or three cartons. One carton holds the humidifier with the steam generator installed, the control humidistat and sensing element, two short steam hoses, hose clamps, mounting plate and lag screws, and a clear drain hose. - Page 5 The mounting surface should be a wall capable of supporting the maximum humidifier weight. The maximum operating weight is: Model unit The location chosen should be inside with a minimum ambient temperature of 40°F. and a maximum of 100°F. The humidifier should not be mounted on hot surfaces. The location should be close enough to the air duct so that the length of steam pipe is as short as possible.
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Page 6: Installation
INSTALLATION 4) MOUNTING THE HUMIDIFIER MODEL EHU-701: Making sure the unit is level, hold it against the mounting surface and mark the hole pattern. Attach the units to studs or other sturdy structure with the two 3/8"× 1½" lag screws provided. MODELS EHU-703 &... -
Page 7: Water Supply
6) WATER FILL SUPPLY Connect the unit to the building water supply (25 to 125 psig pressure). Install a shut-off valve near the humidifier. Connect the water supply to the 3/8" tube compression fitting on the fill valve adaptor. NOTE: ORDINARY (POTABLE) TAP WATER IS RECOMMENDED. IF POTABLE WATER IS NOT AVAILABLE, CONSULT THE FACTORY (SEE "WATER QUALITY AND TREATMENT SECTION OF THIS MANUAL, PAGE 23, FOR MORE INFORMATION). - Page 8 c. Use the template provided to cut installation holes in the duct for the dispersion tube as in Figure 7-2 (and optional drain tube, Figure 7-3). d. Insert the dispersion tube into the duct so the holes face upward. Fasten the mounting plate to the outside of the duct with sheet metal screws.
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Page 9: Control Wiring
CONTROL WIRING NOTE: Wiring to the low-voltage controls should not run in the same conduits as the power supply wiring because faulty signals could result. The use of either a metal conduit or shielded wire is required for all the control and / or safety wiring. When using metal conduit, the conduit must extend the entire length of the wire, and the conduit must be grounded at the humidifier cabinet. - Page 10 Figure 10-1 Humidifier Connections Wall Mounted Control Humidistat: Wall-mounted humidistats are usually installed 4 ft. to 5 ft. above floor level. Often, the best location is beside a thermostat that controls temperature in the same space that is to be humidified, if that loca- tion meets the following criteria: •...
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Page 11: High Limit Duct Humidistat
Figure 11-1 1.9 - 3.9 Vdc Black Voltage Source White Ground Green Stat In Set BJ4 Stat Input Selector to 1.9 - 3.9 Vdc Set BJ5 Voltage Source to 12 Vac 4-20 mA & 0-10 Vdc Setting* Voltage Source Ground Stat In Set BJ4 Stat Input Selector to 0-10 Vdc or 4-20 mA... -
Page 12: Audible Alarm
Figure 12-1 Low-Voltage Low-Energy Controls Main Control Humidistat High Limit* Humidistat Air Flow* Switch N.O. Alarm Relay *Must be closed to run 12) AUDIBLE ALARM There is an external alarm circuit provided. When an alarm condition is detected in the diagnostic routines, a relay contact closes allowing activation of an external Class II device connected between terminals 27 &... -
Page 13: Section 2: Start-Up And Operation Display (Instrument) Panel
INSTRUMENT PANEL DEMAND CURRENT % POWER DIAGNOSTIC FILL DRAIN HIGH WATER TANK OFF MODE SELECT TANK ON/OFF DRAIN ON/OFF Indicates when the fill valve is energized to add water to the steam FILL LIGHT generator. Indicates when the drain valve is energized to drain water from the DRAIN LIGHT steam generator. -
Page 14: Before Turning On The Power
START-UP PROCEDURE FOR ARMSTRONG SERIES EHU-700 HUMIDIFIERS The following steps should be performed on all newly installed Series EHU-700 Humidifiers to ensure that the humidifier and the entire humidification system functions correctly. Figure 14-1 Low Voltage Terminal Block TURN ON POWER AT THE CIRCUIT BREAKER 6) The following should happen: a) The Demand Mode and Tank Off lights will be illuminated. - Page 15 If the stat demand display is greater than 35% and the unit does not begin filling, press the mode select button three times and the diagnostic mode indicator will light. Note the diagnostic message and refer to the diagnostics information in the troubleshooting section of this manual (page 20).
- Page 16 15) Verify that all of the input/output circuits are functioning properly by entering the input/output diagnostics mode. Press the mode button until the diagnostics indicator lights and wait ten seconds. The unit will do a complete self-diagnostic check. See CO in the diagnostics section of this manual (page 20) for more information.
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Page 17: Troubleshooting Guide
TROUBLESHOOTING GUIDE CAUTION!: Disconnect the electric power supply at the circuit breaker or switch whenever the unit is to be inspected or serviced. DO NOT USE THE TANK ON/OFF SWITCH ON THE HUMIDI- FIER BECAUSE THIS SWITCH DISCONNECTS THE STEAM GENERATOR TANK ONLY. PRINCIPLE OF OPERATION - AN OVERVIEW The Armstrong Series EHU-700 electronic steam humidifier converts ordinary tap water to steam and distributes it within... -
Page 18: Operational Guidelines
A high-water float switch prevents water carry-over into the duct due to an excessive water level in the tank. When the high water limit is reached the HIGH WATER light comes on and the fill valve is blocked until some water is boiled away and the water level drops. This is common during startup. If the high water light comes on and the water level is in the lower half of the steam generator, contact the factory for assistance. - Page 19 Monitoring Current: While the unit is filling, the current should increase. As the current approaches the maximum rating of the unit, it increases more slowly, especially in higher capacity units. With the tank on, and the fill and drain circuits idle, the current should fall slowly. When the unit is draining, the current should decrease at a moderate rate.
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Page 20: Diagnostics
EHU-700 DIAGNOSTICS THE Series EHU-700 has built in diagnostics to detect system problems early, before they become severe. If possible, the diagnostic routine performs corrective measures. If necessary, the unit is shut- down and a dry contact is closed to enable a remote alarm. The diagnostic messages that result in the unit being shutdown are displayed automatically. - Page 21 C04: HIGH LIMIT CIRCUIT: When the humidity in the duct reaches the high limit stat set-point, the circuit will open and the microcontroller will de-energize the contactor. The diagnostic mode will display the message C04 and the fill solenoid is blocked. C05: DRAIN SYSTEM FAILURE: This routine checks for a failure to reduce current if the drain valve is energized for more than...
- Page 22 C09: I/O DIAGNOSTICS If the display mode selection is left in the diagnostic mode for 10 seconds, the Input/Output circuit diagnostic check will begin. The display will show the message C09, the tank will be off, and the diagnostics mode light will remain on. Output Circuits: The diagnostics will first check all the output circuits: fill valve, drain valve, and tank contactor to make sure they are working.
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Page 23: Water Quality And Treatment
WATER QUALITY AND TREATMENT FOR EHU SERIES HUMIDIFIERS GENERAL Series EHU 700 electronic humidifiers use ordinary tap water in their operation. The quality of this water affects both the operation and the maintenance of the humidifier. How the EHU works: The EHU is an electrode boiler. -
Page 24: Conductivity Too High
Results: -Excessive time needed to reach set point during star-up. -Poor humidity control. Remedy: -Add 1/2 teaspoon of Epsom salts to the fill cup. After start-up the automatic drain program should maintain the unit at full capacity. -If problem persists, contact the factory. WHEN WATER CONDUCTIVITY IS TOO HIGH Indicators: -Water level just touching tip of electrodes. -
Page 25: Maintenance
EHU-701, -703, -704 Series Electronic Steam Humidifier Steam Generators Complete Item Part No. 1 Ph Low Voltage D4417 120,208,240,277 Volts 1 Ph High Voltage w/Barrier D4418 380,480,600 Volts D4415 3 Ph Low Voltage (208, 240, 277 volts) D4416 3 Ph High Voltage w/Barrier (380, 480, 600 volts) D262A 3 Ph/1 Ph Low Voltage (120, 208, 240, 277 volts) D262... - Page 26 Valves and Mechanical Parts Item Part No. B2717 Drain Valve Assembly w/ Hose & (2) Clamps B2582A-1 Float Switch Assembly B2582A-2 Float Switch Assembly (Far Tank) B4482 Fill Valve w/Flow Washer & Straight 3/8" Compression Fitting B4480 Fill Valve w/Flow Washer & 90 Degree 3/8" Compression Fitting B4481 Fill Valve Assembly Less Flow Washer A8608...
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Page 27: Electrical Parts
Item Part No. C2059 Display PC Board A22925 Control PC Board Less Current Module A22926 Control PC Board Less Current Module B2895-7 CM-7 Current Module B2895-12 CM-12 Current Module B2895-14 CM-14 Current Module B2895-16 CM-16 Current Module B2895-20 CM-20 Current Module B2895-24 CM-24 Current Module B2895-32 CM-32 Current Module B2895-40 CM-40Current Module... - Page 28 Figure 28-1. EHU-700 Parts List Figure 28-2. EHU-700 Steam Generator Repair Parts List...
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Page 29: Recommended Maintenance
MAINTENANCE RECOMMENDED MAINTENANCE SCHEDULE 1 TO 2 DAYS AFTER START UP 1 MONTH TO 1 YEAR STEAM GENERATOR MAINTENANCE General: The steam generator is basically the only part of the EHU that requires regular maintenance. This maintenance may include cleaning or replacing the tank itself or the electrodes. We recommend sub- stituting a spare generator in order to minimize downtime and labor requirements. -
Page 30: Tank Removal And Replacement
If the electrodes begin to disintegrate, the tank may turn black or red, and arcing or flashing may be visible inside the tank while it is operating. IF YOU NOTICE EXCESSIVE ARCING, SHUT THE UNIT OFF AND CALL THE FACTORY BEFORE RE-STARTING UNIT. To replace the electrodes, please refer to the "Tank Disassembly and Electrode Replacement"... -
Page 31: Chemical Tank Cleaning
STEAM GENERATOR CHEMICAL CLEANING PROCEDURE This procedure is intended as a guide only for the chemical cleaning of the generator in all EHU mod- els. Read and follow label directions on any cleaning product. Check local codes before disposing of chemicals. - Page 32 12) Reassemble tank. Make sure o-rings are still on electrode terminals. Also check condition of steam generator o-ring. After a couple cleanings, it will need to be replaced. Make sure o-ring is sealed in its groove and not pinched when halves are put together. Do not over-tighten nuts that hold electrodes in place.
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Page 33: Fill And Drain Valve Repair
TANK DISASSEMBLY, CLEANING, AND ELECTRODE REPLACEMENT MODELS EHU-703 AND 704, SINGLE AND THREE PHASE 1) Using a 7/16" wrench, disconnect the jumper wires from the steam generator. 2) Remove 24 metal clips by pushing gently on top of each clip with a screwdriver while cupping the clip with the other hand. -
Page 34: Ehu-701, Single And Three Phase
MODEL EHU-701, SINGLE AND THREE PHASE 1) Remove 24 metal clips by pushing gently on top of each clip with a screwdriver while cupping the clip with the other hand. 2) Clean the inside of the steam generator thoroughly unsing a scraper, stiff bristle brush and/or water spray and rinse with clear water. - Page 35 b) While the tank is out, look into the lower end of the tank. Make sure the drain screen is in place. Also check for accumulations of lime at the bottom of the tank. Refer to "Steam Generator Disassembly" and "Cleaning Procedure" sections to rectify these problems. 3) If the tank drains well when the water level is high but poorly or not at all when it is low, check the duct pressure where the dispersion tube is mounted.
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Page 36: Humidistat Data
HUMIDISTAT DATA AUTOCAL PROCEDURE 1. Measure the room humidity near the humidistat with an accurate hygrometer. 2. Turn the humidistat set point dial to match the reading of the hygrometer. 3. Push and hold the Autocal button for more than 3 seconds or until the internal red light turns On and Off. - Page 37 DIMENSIONS Figure 37-1. Dimension drawing. Duct Humidistat Wiring From Security Screw 3-1/4" (83 mm) Base Cover 1-1/4" (32 mm) 2-7/8" (71 mm) Note: Specifications and equipment are subject to change without prior notice. TABLE 5: SENSOR CHARACTERISTICS Voltage between black and white wire, terminals #6 and #7 HUMIDITY SENSOR OUTPUT 1.05 V 1.19 V...
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Page 38: High Limit Humidity Sensor
AIR SUPPLY HIGH LIMIT HUMIDITY SENSOR The A 17898 (H270) includes a high limit circuit. This allows the use of a second humidity in the supply air. Input signal goes to terminals #8 on the humidistat. High limit set point is preprogrammed at 85%. -
Page 39: Application Example
APPLICATION EXAMPLE Steam humidification system controlled by a 0 to 10 Vdc valve wired to output #1. Remote humidity display using 0 to 5 Vdc signal is wired to output #2. The humidity sensor is located in the return air duct. - Page 40 Dimensional Information EHU-704 Dimensions Description "A" Width "B" Height "C" Depth "D" Tank Drain - Side "E" Tank Drain - Front "G" Tank #2 Drain - Front "H" Steam Outlet #1 "I" Steam Outlet #2 "J" Water Supply - Side* "K"...
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