HP Modular Cooling System User Guide Part Number 399325-002 February 2007 (Second Edition)
© Copyright 2006, 2007 Hewlett-Packard Development Company, L.P. The information contained herein is subject to change without notice. The only warranties for HP products and services are set forth in the express warranty statements accompanying such products and services. Nothing herein should be construed as constituting an additional warranty. HP shall not be liable for technical or editorial errors or omissions contained herein. Microsoft, Windows, and Windows NT are U.S.
Contents Overview..................................................................................................................................... 5 Introduction .............................................................................................................................................. 5 Configuration factors..................................................................................................................... 7 Optimum environment and site requirements ................
Environmental specifications ........................................................................................................... 62 HP 10642 G2 Rack specifications............................................................................................................. 62 Replaceable parts and maintenance and service information ........................................................... 63 Replaceable parts .......................................................................................
Overview In this section Introduction ............................................................................................................................................. 5 Introduction The HP Modular Cooling System is an air and water heat exchanger that removes high levels of excess heat generated by equipment installed in HP 10642 G2 Racks.
Item Reference 3 Management module 4 Front door 5 AC transfer switch 6 Water group controller 7 Condensation pump assembly 8 Magnetic solenoid valve 9 Fan units 10 Rear door 11 Power connectors and RJ-45 connector 12 Leveling feet Overview 6
Configuration factors In this section Optimum environment and site requirements ............................................................................................... 7 Site preparation ....................................................................................................................................... 7 Optimum environment and site requirements CAUTION: Contaminated water may cause decreased cooling capacity or disruption in service.
Installation In this section MCS kit contents ...................................................................................................................................... 8 Rack hardware kit contents........................................................................................................................ 9 Required tools..........................................................................................................................................
Rack hardware kit contents 1. M6 screws (50) 2. Cage nut insertion tool (1) 3. M5.5 x 10 self tapping screws (6) 4. M6 cage nuts (50) 5. T-25 Torx bit (1) 6. Cable management bracket (6) 7. Rack ID plate (1) 8. Leveling foot base (6) 9. Documentation CD (1) 10. Hook-and-loop cabling strap 12.7-cm (5 in) clip (1) 11. Hook-and-loop cabling strap 20.3-cm (8 in) clip (1) 12. Hook-and-loop cabling strap 30.
• Counter hold wrench (included with your MCS kit contents) • Bubble level Installing the MCS unit WARNING: The MCS unit and rack are shipped together on a heavy duty shock pallet weighing approximately 2000 lb. HP recommends hiring professional movers to move the heavy duty shock pallet, and then remove the MCS unit and rack from the pallet and into to the final location. CAUTION: Contaminated water may cause decreased cooling capacity or disruption in service.
5. Remove the rear caster plate. 6. Lower the unit by raising the two rear leveling feet on both the MCS unit and the rack so that the MCS unit can move freely on the remaining casters.
7. Roll the MCS unit and rack into the final location while guiding the In and Out water hoses through the raised floor opening. 8. Using a bubble level, adjust the leveling feet to level the MCS unit and rack.
9. Install and route the two drain hoses to the drain collection system catch basin. a. Install the blue drain hose by inserting one end of the hose into the plastic collar quick connect on the condensation pump, and then route the other end into either the condensation return line or the gravity drain collection system catch basin.
b. Install the clear drain hose by inserting one end of the hose into the condensation collection pan, and then route the other end into the gravity drain collection system catch basin. NOTE: Position the gravity drain collection system below the condensation collection pan, allowing gravity to draw the water out of the condensation collection pan and into the gravity drain collection system catch basin. 10. Plug the network cable into the RJ-45 connector located above the In and Out water hoses. 11.
WARNING: To reduce the risk of electric shock or damage to the equipment: • Do not disable the power cord grounding plug. The grounding plug is an important safety feature. • Plug the power cord into a grounded (earthed) electrical outlet that is easily accessible at all times. • Unplug the power cord from the power supply to disconnect power to the equipment. • Do not route the power cord where it can be walked on or pinched by items placed against it.
. Turn on the water to the prearranged facility water lines. 17. (Optional) Remove the two screws from the bottom brackets on the MCS frame. 18. (Optional) Align the access panel with the two holes from step 17. 19. (Optional) Secure the access panel to the MCS frame using the two screws you removed in step 17.
WARNING: To reduce the risk of electric shock or damage to the equipment: • Do not disable the power cord grounding plug. The grounding plug is an important safety feature. • Plug the power cord into a grounded (earthed) electrical outlet that is easily accessible at all times. • Unplug the power cord from the power supply to disconnect power to the equipment. • Do not route the power cord where it can be walked on or pinched by items placed against it.
b. Enter the password in the password field. The default password is Admin. The Main Menu screen appears. 6. Enter the product ID and serial number. The product ID and 10-digit serial number are located on a label inside the rear MCS unit door.
a. From the Main Menu screen, enter 3 Factory Default. The Default Product Identification screen appears. NOTE: MCS units with part number 405930-001 that have been upgraded from the Management Controller version 1.0 may not have the product ID or serial number on the unit. In such cases, use AF098A as the product ID. b. Enter 2 Product ID MCS to set the product ID. c. Enter 3 Serial Number MCS to set the serial number. d. Press Esc to return to the Main Menu screen. 7.
a. From the Main Menu screen, enter 1 Network Configuration. The Menu Network Configuration screen appears.
b. Enter 1 IP Configuration. The IP Configuration screen appears. c. Enter 4 Enable/Disable DHCP to disable DHCP. d. Enter 1 IP Address, and then enter the new IP address. e. Enter 2 IP Subnet mask, and then enter the IP subnet mask. f. Enter 3 IP Def. Router, and then enter the gateway. NOTE: MCS units with part number 405930-001 that have been upgraded from the Management Controller version 1.0 may not have the product ID or serial number on the unit. In such cases, use AF098A as the product ID. 8.
a. Return to the Main Menu Network Configuration screen. b. Enter 4 Activate Actual Values. c. 9. Enter y at the prompt to reboot. You must reboot for the IP settings, product ID, and serial number values to be activated. Access the Management module through the web interface. a. Launch a supported browser. The browser window appears. b.
c. 11. Click Sign In. Verify that the water source is available and turned on by viewing the Water Flow status in the Overview menu. Be sure that you do not have a water flow warning as shown in the following figure.
12. Click Setup>Accounts, and then change the Web Admin and Web User passwords. 13. Click Save Settings. 14. (Optional, but recommended) Click Setup>Management>Remote Access, then select the SSL Enable radio button and optionally enter an SSL key. 15. Click Save Settings.
16. Click Setup>Management>Trap Receivers to set up your trap receivers. 17. Click Save Settings. 18. (Optional but recommended) Click Setup>Management>SNMP Managers to set up your SNMP managers. 19. Click Save Settings. Configuring the IP address through the web interface 1. View the IP address received from DHCP on the operator display.
2. Access the Management module through the web interface. a. Launch a supported browser. The browser window appears. b. In the Address field (Internet Explorer) or the Location field (Mozilla), enter http://ipaddress (where ipaddress is the IP address of the management module). The login screen appears. 3. Log in through the web interface. a. Enter the user name in the User Name field. The default user name is Admin. b. Enter the password in the Password field. The default password is Admin. c. 4.
g. Log in to the new IP address. 5. Verify that the water source is available and turned on by viewing the Water Flow status in the Overview menu. Be sure that you do not have a water flow warning as shown in the following figure.
6. Click Setup>Accounts, and then change the Web Admin and Web User passwords. 7. Click Save Settings. 8. (Optional, but recommended) Click Setup>Management>Remote Access, then select the SSL Enable radio button and optionally enter an SSL key. 9. Click Save Settings.
10. Click Setup>Management>Trap Receivers to set up your trap receivers. 11. Click Save Settings. 12. (Optional, but recommended) Click Setup>Management>SNMP Managers to set up your SNMP managers. 13. Click Save Settings.
Management module In this section Management module overview ................................................................................................................ 30 Management module components ............................................................................................................ 31 Accessing the management module through a terminal emulation program ................................................... 32 Accessing the management module through the web interface............
• Warning Temperature Threshold—Temperature difference above Server Intake Temperature Set Point for temperature warning message • Low Temperature Threshold—Temperature difference below Server Intake Temperature Set Point for temperature warning message The following values are displayed in the web interface for information only: • Fan Speed Target—Displays the percentage of the fan maximum speed • Water Valve—Displays the water valve state • Cooling Module 1 through 3—Displays the Server Intake a
Item Reference Description 2 Used to indicate the internal status of the management module, and to signal warnings and critical alarms.
2. Enter the password in the password field. The default password is Admin. The Main Menu screen appears. Accessing the management module through the web interface 1. Launch a supported browser. The browser window appears. 2.
Software Browser Web browser on a client • Microsoft® Internet Explorer 6.0 with Service Pack 1 (32-bit only) • Red Hat Linux operating system (32-bit only) • Mozilla 1.4 • SUSE LINUX operating system (32-bit only) • Mozilla 1.6 Monitor resolution Minimum supported resolution of 1024 x 768, 16bit high color (maximize browser window for optimal display) Desktop resolution SLES 9 Mozilla 1.6 1 Right-click the mouse, and select Configure Desktop. 2 Select 1152 x 864. 3 Select 75 Hz.
For instructions on changing the password, see the "Accounts menu" section in the HP Modular Cooling System Web Interface User Guide. Only one Admin session and one User session are supported at a time. Sessions can be terminated if a second session is initiated (after successful login), or if a console session timeout occurs. In both situations, the existing session is terminated and the login screen appears. Admin session logins, logouts, and terminations are recorded in the Event Log menu.
1. Connect the external alarm relay module to the sensor jack 1 (see figure below) on the management module according to the instructions provided with the device. The management module LED status light will blink red, yellow, and then green. 2. Press and hold the management module C key for five seconds to confirm the new settings. The management module LED status light turns green when the external alarm relay is ready. 3.
Serial interface In this section HP Modular Cooling System Utility overview ............................................................................................. 37 Configuring HyperTerminal ..................................................................................................................... 43 Configuring Minicom..............................................................................................................................
Main menu Option number Submenu Description 1 Network Configuration Enter or change network properties for the management module. 2 Info Page View parameters for the management module. 3 Factory Default Change parameters back to default settings.
Menu Network Configuration submenu Option number Submenu Description 1 IP Configuration Enter or change the IP configuration for the management module. 2 Change Passwords Enter or change the passwords for the management module. 3 HTTP/Console Timeout [min] Enter or change the minimum HTTP/console timeout for the management module. 4 Activate Actual Values Select to accept changes and restart the unit.
IP Configuration submenu Option number Submenu Description 1 IP Address Enter or change the IP address for the management module. 2 IP Subnet mask Enter or change the subnet mask for the management module. 3 IP Def. Router Enter or change the default router for the management module. 4 Enable/Disable DHCP Select to enable or disable DHCP.
Change Passwords submenu Option number Submenu Description 1 Console Password 'Admin' Change the Admin password. 2 FTP Password 'ftpuser' Change the FTP user password. 3 FTP Password 'ftpadmin' Change the FTP Admin password. 4 HTTP Password 'User' Change the HTTP user password. 5 HTTP Password 'Admin' Change the HTTP Admin password.
Info page The Info page displays the following parameters: • IP Address • Subnetmask • Router/Gateway • MAC Address • SysName • SysContact • SysLocation • Software Version • Hardware Version • Firmware • Serial Number • Manufacture Date • CMC-Info Serial interface 42
Factory Default submenu Option number Submenu Description 1 Set to Factory Default Set the management module to factory default. 2 Product ID MCS Set the MCS unit product ID. 3 Serial Number MCS Set the MCS unit serial number. Configuring HyperTerminal 1. From the Microsoft® Windows® desktop menu, click Start>All Programs>Accessories>Communication>HyperTerminal. The Connection Description window appears. 2. Enter a description and select an icon for the connection.
5. When a connection is established, press Enter and then log in. The Main menu for the management module appears. Follow the onscreen options to configure the management module. Configuring Minicom NOTE: The following example uses Red Hat Linux 3.0. For more information, refer to your Linux operating system Help or documentation. IMPORTANT: Minicom is a utility that is loaded during the installation of Linux.
Operator display In this section Operator display overview ...................................................................................................................... 45 Adjusting the operator display ................................................................................................................. 55 Operator display overview The operator display provides information on the system operation, viewable on the outside of the MCS front door.
Indicators Meaning Actual operator display alarm message Top, Mid, or Bot Fan Mod. Failed Actual web interface alarm message Top, Mid, or Bottom Fan Module Failed Condition Top, middle, or bottom fan module tach is less than its minimum rpm Module Top, middle, or bottom fan module SNMP notification Warning Type of message Warning Solution: 1. Remove the fan unit. 2. Reinstall the same fan unit.
Indicators Meaning Sensors HEX1, HEX2, or HEX3 sensors (this is the water to air heat exchanger unit temperature of the intake to the servers) SNMP notification Warning Type of message Warning Solution: 1. Remove the fan unit. 2. Remove the HEX unit. 3. Reinstall the same HEX unit. 4. Reinstall the same fan unit. If the warning message does not clear after the module is reseated, replace the HEX unit with a CSR part.
Solution: 1. View the Overview menu to distinguish which temperature sensor is different from the other temperature sensors. 2. After discovering which temperature sensor is not working properly, remove that module and reinstall it. If the difference is in the Server Exhaust Temperature, replace the appropriate fan unit. If the difference is in the Server Intake Temperature, replace the appropriate HEX unit.
Indicators Meaning Actual operator display alarm message Water Temp. Out Failed Actual web interface alarm message Water Unit Temperature Output Out of Range Condition Water temperature sensor is not working properly (possible open circuit) Sensors Water group sensor SNMP notification Warning Type of message Warning Solution: 1. Verify the water supply. 2. Verify whether the water temperature is below or above the water temperature expected range. 3. Contact your building supervisor. 4.
1. Verify the water valve is closed. 2. Contact HP, or see the HP website (http://www.hp.com). Leak detector sensor is not working properly Indicators Meaning Actual operator display alarm message Leak detector? Actual web interface alarm message Leak detector Failed Condition Leak detector sensor is not working properly Sensors Leak detector sensor SNMP notification Warning Type of message Warning Solution: Contact HP, or see the HP website (http://www.hp.com).
Solution: 1. Verify the water inlet temperature. 2. Verify that the flow matches the specifications required for heat load. 3. Adjust the temperature assigned in the web interface Intake Temp tab High Temperature Threshold field.
Indicators Meaning Actual web interface alarm message Temperature too low Condition Average server air temperature is lower than the temperature assigned in the web interface Intake Temp tab Low Temperature Threshold field Sensors Air temperature sensor SNMP notification Warning Type of message Warning Solution: 1. Verify water flow matches specifications required for heat load. 2. Verify whether the water temperature is below the expected range. 3.
Indicators Meaning Condition The Water Flow Loss Emergency Door Opening Temperature Threshold has been exceeded or the water flow is less than 2 l/min (.5283 gal/min). Modules or sensors Server Intake Temperature, Water Flow Meter SNMP notification Critical Type of message Alarm Solution: 1. Verify water supply and verify the MCS unit is receiving water. 2. Verify that the water flow is at least 2 l/min (.5283 gal/min) or greater. 3.
Indicators Meaning Actual operator display alarm message Excessive Moisture Actual web interface alarm message The condensation pump has exceeded x cycles Condition The water level has exceeded the permissible level of the condensation pump sensor Modules or sensors Condensation pump sensor SNMP notification Warning Type of message Warning Solution: 1. Look for leaks or determine if condensation is the cause. 2.
NOTE: A 24-hour clock starts when the condensation pump runs for the first time in more than 24 hours. A warning is issued if either the cycle threshold or pump running time is exceeded within the 24-hour window. The clock stops and the counters are reset to zero for warning purposes if the thresholds are not exceeded within 24 hours after the last time the condensation pump runs.
4. Using an 8-mm wrench, reattach the three nuts removed in step 1 to replace the operator display rear cover.
Automatic Door Release Kit In this section Automatic Door Release Kit Overview....................................................................................................... 57 Automatic Door Release Kit Overview The Automatic Door Release Kit is designed as a safety mechanism in the event that the MCS unit shuts off unexpectedly. If the MCS unit shuts off unexpectedly, the electromagnetic locks on the front door, the rear master door, and the rear slave door are immediately deactivated.
Frequently asked questions In this section HP Modular Cooling System frequently asked questions.............................................................................. 58 HP Modular Cooling System frequently asked questions Question Answer What cooling capacity ranges are available in the MCS unit? The cooling capacity of the heat exchanger units depends on the water supply temperature and the server inlet set point.
Question Answer Does the air flow within the MCS unit produce static electricity? Very low humidity levels in the chilled air may produce static electricity. However, static electricity is not a problem if the MCS unit is operated at the specified settings located in the HP Site Preparation Guide and the Environmental specifications listed in this document.
Troubleshooting In this section HP Modular Cooling System troubleshooting ............................................................................................. 60 HP Modular Cooling System troubleshooting Issue Resolution The water flow is low or not flowing. For more information, see the "Temperature Control settings" section in the HP Modular Cooling System Web Interface User Guide located on the Documentation CD included with this product. The fan speed is too low.
Specifications In this section MCS specifications................................................................................................................................. 61 HP 10642 G2 Rack specifications ........................................................................................................... 62 MCS specifications Item Specification Voltage 208–240 VAC +/- 10%, 50–60 Hz Maximum Height (including the rack) 200 cm (78.7 in) Maximum Width (including the rack) 90.9 cm (35.
Thermal and air flow performance Maximum thermal and air flow performance parameters Specifications Air temperature—inlet to rack-mounted components 25ºC (68ºF) Chilled water temperature 7º–10°C (45º–50°F) Total rack-mounted component air flow 2,600 cfm or less at 0 or more pressure drop across the rack-mounted components Chilled water flow rate 21 gal/min Chilled water pressure differential at flow needed to meet thermal specifications 2.
Replaceable parts and maintenance and service information In this section Replaceable parts .................................................................................................................................. 63 Maintenance and service ........................................................................................................................ 63 Replaceable parts The heat exchanger units and fan units are replaceable during real-time operation.
Water quality and leveling requirements, and condensation management In this section Water quality requirements and specifications........................................................................................... 64 Leveling requirements ............................................................................................................................. 66 Condensation management ...............................................................................................................
Hydrological data Acceptable range Free carbonic acid 8–15 mg/dm3 Accompanying carbonic acid 8–15 mg/dm3 Corrosive carbonic acid 0 mg/dm3 Sulphides Free Oxygen < 10 mg/dm3 Chloride ions < 50 mg/dm3 Sulphate ions < 250 mg/dm3 Nitrates and nitrites < 10 mg/dm3 CSB < 7 mg/dm3 Ammonia < 5 mg/dm3 Iron < 0, 2 mg/dm3 Manganese < 0, 2 mg/dm3 Conductivity < 2200 µS/cm Residue on evaporation < 500 mg/dm3 Potassium permanganate consumption < 25 mg/dm3 Suspended matter < 3 mg/dm3 Parti
Closed-loop water specifications Raw water Treated water system Molybdenum (Mo) 50–300 ppm 50–300 ppm Tolytriazole 15–20 ppm 15–20 ppm Suspended solid < 1 µm < 1 µm Monitoring the quality of cooling solutions Depending on the type of installation, it is advisable to put in place certain processes and procedures for monitoring the quality of the cooling solution and for performing preventative maintenance.
Condensation management Any condensation that forms is collected in each individual cooling module and is taken through a discharge tube to a condensation tray integrated in the base assembly. Where multiple cooling modules are used, the condensate discharge tubes are connected to one another using quick connectors. Any condensation that occurs is then removed through this series of connections to the condensation tray.
Technical support In this section Before you contact HP............................................................................................................................. 68 HP contact information............................................................................................................................ 68 Customer Self Repair ..............................................................................................................................
service providers or service partners) identifies that the repair can be accomplished by the use of a CSR part, HP will ship that part directly to you for replacement. There are two categories of CSR parts: • Mandatory—Parts for which customer self repair is mandatory. If you request HP to replace these parts, you will be charged for the travel and labor costs of this service. • Optional—Parts for which customer self repair is optional. These parts are also designed for customer self repair.
doivent être retournées dans l'emballage fourni. Si vous ne retournez pas la pièce défectueuse, HP se réserve le droit de vous facturer les coûts de remplacement. Dans le cas d'une pièce CSR, HP supporte l'ensemble des frais d'expédition et de retour, et détermine la société de courses ou le transporteur à utiliser. Pour plus d'informations sur le programme CSR de HP, contactez votre Mainteneur Agrée local. Pour plus d'informations sur ce programme en Amérique du Nord, consultez le site Web HP (http://www.
• Optional – Teile, für die das Customer Self Repair-Verfahren optional ist. Diese Teile sind auch für Customer Self Repair ausgelegt. Wenn Sie jedoch den Austausch dieser Teile von HP vornehmen lassen möchten, können bei diesem Service je nach den für Ihr Produkt vorgesehenen Garantiebedingungen zusätzliche Kosten anfallen. HINWEIS: Einige Teile sind nicht für Customer Self Repair ausgelegt. Um den Garantieanspruch des Kunden zu erfüllen, muss das Teil von einem HP Servicepartner ersetzt werden.
deberá hacerlo en el periodo de tiempo especificado, normalmente cinco días laborables. Los componentes defectuosos deberán devolverse con toda la documentación relacionada y con el embalaje de envío. Si no enviara el componente defectuoso requerido, HP podrá cobrarle por el de sustitución. En el caso de todas sustituciones que lleve a cabo el cliente, HP se hará cargo de todos los gastos de envío y devolución de componentes y escogerá la empresa de transporte que se utilice para dicho servicio.
reparo pode ser efetuado pelo uso de uma peça CSR, a peça de reposição será enviada diretamente ao cliente. Existem duas categorias de peças CSR: • Obrigatória – Peças cujo reparo feito pelo cliente é obrigatório. Se desejar que a HP substitua essas peças, serão cobradas as despesas de transporte e mão-de-obra do serviço. • Opcional – Peças cujo reparo feito pelo cliente é opcional. Essas peças também são projetadas para o reparo feito pelo cliente.
Technical support 74
Technical support 75
Regulatory compliance notices In this section Regulatory compliance identification numbers ........................................................................................... 76 Federal Communications Commission notice ............................................................................................. 76 Modifications......................................................................................................................................... 76 Cables ..........................
Cables Connections to this device must be made with shielded cables with metallic RFI/EMI connector hoods in order to maintain compliance with FCC Rules and Regulations. Canadian notice This Class A digital apparatus meets all requirements of the Canadian Interference-Causing Equipment Regulations. Cet appareil numérique de la classe A respecte toutes les exigences du Règlement sur le matériel brouilleur du Canada.
Disposal of waste equipment by users in private households in the European Union This symbol on the product or on its packaging indicates that this product must not be disposed of with your other household waste. Instead, it is your responsibility to dispose of your waste equipment by handing it over to a designated collection point for the recycling of waste electrical and electronic equipment.
accordance with US FDA regulations and the IEC 60825-1. The product does not emit hazardous laser radiation. Each laser product complies with 21 CFR 1040.10 and 1040.11 except for deviations pursuant to Laser Notice No. 50, dated May 27, 2001; and with IEC 60825-1:1993/A2:2001. WARNING: Use of controls or adjustments or performance of procedures other than those specified herein or in the laser product's installation guide may result in hazardous radiation exposure.
Power cord statement for Japan Regulatory compliance notices 80
Acronyms and abbreviations CSB chemical species balance CSR Customer Self Repair DHCP Dynamic Host Configuration Protocol DST daylight savings time EEPROM electrical erasable programmable read only memory FTP file transfer protocol GMT Greenwich mean time HTTP hypertext transfer protocol HTTPS hypertext transfer protocol secure sockets IP Internet Protocol MCS modular cooling system NTP network time protocol Acronyms and abbreviations 81
PDU power distribution unit SIM Systems Insight Manager SMTP Simple Mail Transfer Protocol SNMP Simple Network Management Protocol SSH Secure Shell SSL Secure Sockets Layer TCP Transmission Control Protocol TFTP Trivial File Transfer Protocol Acronyms and abbreviations 82
Index A accessing the management module 32, 33 adjusting operator display 45, 55 Air temperature sensor failed 45 alarm relay 35 Alarms and warnings 45 authorized reseller 68 Automatic Door Release Kit 57 C Communication failure 45 condensation management 67 configuration factors 7 configuration utilities 37 configuring HyperTerminal 43 configuring Minicom 44 customer self repair (CSR) 68 E environmental specifications 62 F factory default settings 43 Fan unit failed 45 Fan unit not installed 45 frequent
site requirements 7 specifications 61, 62 specifications, environmental 62 support 68 T technical support 68 telephone numbers 68 Temperature above threshold (Warning Temperature Threshold field) 45 Temperature below threshold (Low Temperature Threshold field) 45 terminal emulator session 32 thermal air flow performance 62 troubleshooting 60 U Uneven heat load 45 W Water flow sensor is not working properly 45 Water flow valve is closed 45 water quality 64, 66 Water temperature input is out of range 45 Wa
