Warning: If the information in this manual is not followed exactly, a fire or explosion may result causing property damage, personal injury or death. Do not store or use gasoline or other flammable vapor and liquids in the vicinity of this or any other appliance. Improper installation, adjustment, alteration, service or maintenance can cause injury or property damage. Refer to this manual. For assistance or additional information consult a qualified installer, service agency or the gas supplier.
| Index Index 1 Key to symbols and safety instructions . . . . . . . . . . . . 3 1.1 Key to symbols . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 1.2 General safety instructions . . . . . . . . . . . . . . . . . . . 3 2 Warning . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 3 Appliance details . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 3.1 520 HN specifications (Technical data) . . . . . . . . 7 3.2 Unpacking the 520 HN heater . . . . . . .
Key to symbols and safety instructions | 3 1 Key to symbols and safety instructions 1.1 Key to symbols Warnings Warnings in this document are identified by a warning triangle printed against a grey background. Keywords at the start of a warning indicate the type and seriousness of the ensuing risk if measures to prevent the risk are not taken.
| Key to symbols and safety instructions Danger from escaping flue gases ▶ Ensure all vent pipes and chimneys are not damaged or blocked. ▶ Connect only one appliance to each vent system or chimney liner. ▶ The venting system piping must not feed into another air extraction duct. ▶ Do not route the flue system piping through or inside another air extraction duct. Danger of explosion of flammable gases ▶ Work on gas components may only be carried out by a trained and certified installer.
Key to symbols and safety instructions | 5 Flooding ▶ After a flood, do not use the appliance if any part has been submerged. Damage to appliances that have been submerged can be quite severe and pose numerous safety risks. ▶ Every appliance that has been submerged must be replaced. For your safety ▶ Do not store or use gasoline or other flammable, combustible or corrosive vapors and liquids in the vicinity of this or any other appliance. DANGER: Fatal accidents! Carbon monoxide poisoning.
| Warning WARNING: Fire danger! ▶ Keep appliance area clear and free from combustible materials, gasoline and other flammable vapors and liquids. WARNING: Personal Injury from toxic chemicals. ▶ Toxic chemicals, such as those used for boiler treatment, shall not be introduced into the potable water used for space heating. NOTICE: ▶ Do not obstruct the flow of combustion and ventilation air. WARNING: Personal Injury from toxic chemicals.
Appliance details | 7 Overheat prevention (temperature limiter). Capacity Minimum input BTU/hr 30 735 Btu/hr Maximum input BTU/hr 117 000 Btu/hr Minimum output BTU/hr 23 906 Btu/hr Maximum output BTU/hr 91 525 Btu/hr % 80% inches ¾” NPT Thermal efficiency (Efficiency in %) Gas Requirement Gas connection Inlet gas pressure under maximum operation:* Propane water column 10.5” - 14” * To measure Gas Pressure, see Measuring Gas Pressure, chapter 3.7. Natural Gas water column 5.
| Appliance details - 45F rise @ 4.1 gpm - 50F rise @ 3.7 gpm - 55F rise @ 3.4 gpm - 65F rise @ 2.8 gpm - 77F rise @ 2.4 gpm - 90F rise @ 2.0 gpm Connections: Bottom of heater Dimensions Depth inches 8.66” (220 mm) Width inches 16.73” (425 mm) Fig. 2 25.
Appliance details | 9 3. The appliance must be isolated from the gas supply piping system by closing its individual manual gas shutoff valve (not supplied with heater) during any pressure testing at pressures in excess of ½ Psig (3.5 kPa). The appliance and its gas connection must be leak tested before placing the appliance in operation. 4. Keep water heater area clear and free from combustibles and flammable liquids. Do not locate the heater over any material which might burn. 5.
| Appliance details 3.4 Dimensions and installation clearances 8,66" (220) 4,92"(125) G A D 38 36 F C 39 B 37 4 E 10 5 26 40 35 23 2,50" (63.5) 34 20 11 H 1,97" (50) 3,82" (97) Fig. 3 [4] [5] [10] [11] [20] [23] [26] 6720608036-01.
Installation instructions | 11 ▶ 2. Locate the heater where venting, gas and plumbing connections are feasible and convenient. ▶ 3. The hot water lines should be kept short to save energy. Centrally locating the water heater is best. It is always best to have hot water lines insulated. WARNING: The water in this water heater is cold and always remains cold except for the times that hot water is being used. Fig. 4 ▶ DO NOT INSTALL IN AN AREA WHERE IT COULD FREEZE.
| Installation instructions WARNING: before starting installation: ▶ check that there are no loose parts inside the appliance ▶ ensure that gas pipe, gas valve, and burner have no damage and are properly fitted. ▶ Read chapter 3.2 to verify proper gas type and to check all parts are included in box. pair of studs and then the heater should be attached to the support boards, see Fig. 7. ▶ Install the two included L shaped hooks to wall studs or support board 13 ¼” apart (See Fig. 7).
Installation instructions | 13 combustion air per the National Fuel Gas Code. Consult a HVAC specialist if your air infiltration rate is questionable. Appliances located in confined spaces: The confined space must be provided with two permanent openings, one commencing within 12 inches of the top and one commencing within 12 inches of the bottom of the enclosure. Each opening must have a minimum free area of one square inch per: • • • 1000 Btu/hr if all air is taken from inside the building.
| Installation instructions WARNING: ▶ Do not combination vent with a power vented appliance. 4.5.1 Horizontal venting WARNING: ▶ Horizontally venting to a vertically constructed vent stack along an outside wall of a building is not permissible. Vent termination: The gas vent constructed of double wall Type B gas vent must terminate above the roof surface with a listed vent cap at a height that's in accordance with Fig. 9 and table 5, provided they are at least 8 feet (2.
Installation instructions | 15 5” X 6” ADAPTOR USED AT HIGH ALTITUDE Fig. 10 recommended. The masonry chimney may have to be tile or metal lined before the insertion of the gas vent pipe; check local codes for clarification. The lining material must be listed for use only with naturally drafting, draft hood equipped gas appliances. Follow manufacturer's instructions for installation of listed lining material. You may not vent any other fuel burning appliances into any free space remaining in the chimney.
| Installation instructions 4.6 GAS VENT TERMINATIONS FOR LISTED VENT CAPS Roof pitch H (minimum) feet meters Flat to 6/12 1.0 0.30 6/12 to 7/12 1.25 0.38 Over 7/12 to 8/12 1.5 0.46 Over 8/12 to 9/12 2.0 0.61 Over 9/12 to 10/12 2.5 0.76 Over 10/12 to 11/12 3.25 0.99 Over 11/12 to 12/12 4.0 1.22 Over 12/12 to 14/12 5.0 1.52 Over 14/12 to 16/12 6.0 1.83 Over 16/12 to 18/12 7.0 2.13 Over 18/12 to 20/12 7.5 2.27 Over 20/12 to 21/12 8.0 2.
Installation instructions | 17 GAS CONNECTIONS ▶ Install a manual gas shut off valve, on the gas supply line. ▶ Install a union when connecting gas supply. ▶ Attach the appliance regulator to the inlet gas pipe. ▶ The minimum diameter required for any appliance connector used is ¾” NPT. ▶ National Fuel Gas Code requires that a sediment trap (drip leg) be installed on gas appliances not so equipped. The drip leg must be accessible and not subject to freezing conditions.
| Installation instructions GAS LINE SIZING The gas supply piping should be sized according to the applicable code for a maximum draw of 117,000 BTUH. Measure the length of gas supply line and use the tables in Fig. 14 or the gas line manufacturer’s sizing tables to determine the pipe diameter necessary to accommodate the BTU demand of the unit. If there are more gas appliances drawing on the same line, size the gas line according to the total maximum amount of BTU draw for all appliances.
Installation instructions | 19 FOR LP GAS Maximum Capatity of Pipe in Thousands of BTU per Hour of Undiluted Petroleum Gases (at 11 inches Water Column Inlet Pressure) (Based on a Pressure Drop of 0.5 Inch Water Column).
| Installation instructions 4.7 Measuring gas pressure 4.8 Connecting manometer ▶ Shut off gas. ▶ Remove front cover and locate inlet gas pressure measuring point on the left side, see Fig. 14. ▶ Loosen screw from test point on the left side and connect manometer tube on test point. Water connections When facing the heater, the ½ ” cold water inlet is on the bottom right and the hot water outlet is on the bottom left.
Operation instructions | 21 A small electric mini tank water heater (4-6 gallon size) must be used for this application and designed so the pump will circulate the water through the mini-tank and the building's hot water return loop only. A timed or thermostatically controlled operation of the pump is commonly done. The 520 HN must be plumbed in line before the mini-tank water heater. Contact Bosch Water Heating if further instruction is needed. 5 Operation instructions 5.
| Operation instructions ▶ The gas valve must be shut off by putting the ON/OFF switch to position OFF Wait five (5) minutes to clear out any gas. If you smell gas, STOP! Follow “B” in chapter 4.1. If you do not smell gas, go to the next step. Fig. 18 ▶ Close installer supplied manual gas shutoff valve on the supply line to the heater. 5.4 Fig. 17 ▶ This water heater is equipped with a safety pilot burner and an automatic ignition control system.
Operation instructions | 23 6720608036-09.1Av Fig. 21 Fig. 20 ▶ Turning the flow control knob clockwise restricts water flow. This provides higher temperature because the water is moving slower, spending more time over the burner flames. Turning flow control knob fully clockwise also lowers the activation rate (water flow needed to turn the heater on) to 0.5 gpm. ▶ Turning the flow control knob counter-clockwise increases water flow.
| Maintenance and service Every 2 years ▶ Inspect heat exchanger fins for soot, debris or blockage. Clean if necessary (5.5) ▶ Clean and Lubricate water valve ( 6.2) ▶ Empty the appliance of all water. Every 3 to 5 years ▶ Rebuild water valve with parts kit (part# WVKITCT) ( 6.2) ▶ Clean pilot assembly and clean or replace orifice ( 6.3) 1 3 6.2 2 6720608032-12.1Av Fig.
Maintenance and service | 25 valve can result in decreased performance or water leaks in the heater. 6.3 Pilot Inspecting pilot The pilot should burn with a clean sharp blue flame. The flame should fully engulf the tip of the thermocouple. If it does not, clean the pilot assembly per procedure below. Cleaning pilot assembly Shut off gas supply to the heater using installer supplied gas shutoff valve. Remove 2 screws mounting pilot burner to front of burner assembly.
| Troubleshooting Fig. 24 7 Troubleshooting 7.1 Introduction Many of the questions customers ask regarding operation of this unit can be answered by following the troubleshooting steps as outlined below. Visit our web site at www.boschclimate.us for more detailed troubleshooting bulletins. For best results, perform each step before proceeding to the next. The suggested solutions may require that the cover be taken off. (See chapter 3.5). 7.
Troubleshooting | 27 – With water flowing and heater sparking, apply flame from a match or lighter to the rear of the pilot burner. Avoid applying flame to flame sensor. If main burners only light, repeat procedure and watch for brief flame from pilot burner: 2. If pilot does not light: – Measure voltage between pilot electrovalve wire connection and ground when heater is sparking (Do not disconnect wire); Voltage must be at least 1.1VDC. If less, contact Bosch Tech Support.
| Troubleshooting flow within the tankless heater, decreasing it below activation point, which shuts off the burners. The end result is nothing but cold water coming out of the outlet. Reduce the amount of cold water to be mixed by turning the gas control knob clockwise for lower hot water temperatures. See chapter 4.4 for details in lowering temperature. 5. A temperature limiter (ECO) is tripped. The water heater does not have a thermostat.
Troubleshooting | 29 (directly after the pressure tank on well systems) may be an effective way to maintain constant water pressure to the water heater. 5. If the inlet water temperature is not steady then the hot water temperature from the water heater will fluctuate. The 330 PN modulates its burners when the flow rate is changed; it does not have a thermostat and will not adjust to changes in inlet water temperature. 6.
| Protecting the environment 4.Be sure to run only one major fixture at a time with this water heater. Opening too many taps at one time can disperse water flow resulting in diminished flow or pressure at all outlets ▶ Define the temperature you want. This way you have the precise water flow needed (mixing cold water to regulate temperature will increase the water flow with consequent waste of water). 7.
Interior components and diagram parts list | 31 9 Interior components and diagram parts list 9.1 Interior components 4 30 5 10 51 9 26 11 22 21 20 6720608036-04.3AL Fig.
| Interior components and diagram parts list 9.2 Components diagram 7 6 8 10 36 40 33 39 45 42 46 31 36 35 47 11 15 18 16 13 14 17 49 43 52 19 12 3 20 48 21 25 53 50 26 22 44 24 51 27 28 37 4 5 2 23 38 1 34 29 30 41 32 6720608036-05.2 JF Fig.
Interior components and diagram parts list | 33 9.
| LIFETIME LIMITED WARRANTY FOR BOSCH TANKLESS WATER HEATERS 10 LIFETIME LIMITED WARRANTY FOR BOSCH TANKLESS WATER HEATERS MODELS COVERED This limited warranty is provided by Bosch Thermotechnology Corp. (BTC) and covers models 520 HN and 520 PN (hereinafter referred to as "Water Heater"). This warranty is provided as long as the Water Heater remains in the possession of the original purchaser and installed at its original place of installation.
Installer Checklist to be completed by installer upon installation | 35 CONSEQUENTIAL OR SIMILAR DAMAGES INCLUDING, WITHOUT LIMIITATION, INJURY OR DAMAGE TO PERSONS OR PROPERTY OR DAMAGES FOR LOSS OF USE, LOST PROFITS, INCONVENIENCE OR LOSS OF TIME. NOTE THAT ANY REPAIRED OR REPLACED PRODUCT WILL BE WARRANTED FOR ONLY THE UNEXPIRED TERM OF THE ORIGINAL WARRANTY.
