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 Safety instructions . . . . . . . . . . . . . . . . . . . . . . . . . 3 2 Warning . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 3 Appliance details . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.1 520 PN specifications (Technical data) . . . . . . . . 3.2 Unpacking the 520PN 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 Insufficient ventilation may cause toxic flue gas to escape. Risk of poisoning. ▶ Never close off or reduce the size of the air intake and outlet openings. ▶ The appliance must not be operated until any obstructions have been removed. ▶ Inform the system operator in writing of the problem and the associated dangers. Danger from escaping flue gases ▶ Ensure all vent pipes and chimneys are not damaged or blocked.
Key to symbols and safety instructions | 5 Maintenance Customers are advised to: ▶ Sign a maintenance and inspection contract with an authorized contractor. Inspect and maintain the water heater as necessary and on a yearly basis. Service as needed. ▶ Use only genuine spare parts. 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.
| Warning NOTICE: ▶ If a water heater is installed in a closed water supply system, such as one having a backflow preventer in the cold water supply line, means shall be provided to control thermal expansion. Contact the water supplier or local plumbing inspector on how to control this situation. WARNING: System damage! ▶ If a relief valve discharges periodically, this may be due to thermal expansion in a closed water supply system.
Appliance details | 7 • CAUTION: ▶ Any changes or modifications not expressly approved by the party responsible for compliance could void the user’s authority to operate the equipment.
| Appliance details Height inches (mm) Weight 25.75” (655 mm) pounds (kg) 35 pounds (16 kg) Gas types Natural Gas LP Gas Venting Natural Draft Minimum height feet 6* with no elbows inches 5” Vertical termination Vent diameter Sidewall termination only with AQ4 power vent kit Table 2 1) To measure Gas Pressure, see Measuring Gas Pressure, chapter 4.8, page 19. 3.2 Unpacking the 520PN heater This heater is packed securely.
Appliance details | 9 3.4 Dimensions and installation clearances Fig. 3 [4] [5] [10] [11] [20] [26] [36] Dimensions in Inches and (mm) [37] Hole for fixing to wall [38] Exhaust pipe to connector [39] Draft diverter with flue gas monitor [40] Gas valve [49] Observation window [102]Piezo Heat exchanger Burner Temperature control Water valve Gas connection Output control Front cover Dimensions inches (mm) 520 PN Table 3 520 PN A B 16.73” 25.
| Installation instructions ▶ 2. 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. DO NOT INSTALL IN AN AREA WHERE IT COULD FREEZE. Fig.
Installation instructions | 11 4.3 Heater placement and clearances The 520 PN is design certified for installation on a combustible wall (see 4.4 Mounting installation) provided the wall is not covered with carpet or other fabric material. For installations in an alcove or closet, maintain the minimum clearances to combustible and non-combustible materials listed below. See also Fig. 4. A. Top 12 inches (306 mm) B. Front 4 inches (100 mm) C. Back 0 inches D. Sides 4 inches (100 mm) E.
| Installation instructions 1 2 3 Fig. 7 Support board [1] Wall studs [2] Support board [3] 1”x4” Space board unit. When all requirements are followed, the unit will operate properly and safely. However, there may still be a risk of freezing due to negative draft if all the combustion appliances in the building or structure are not being supplied with a sufficient amount of make-up air.
Installation instructions | 13 4.6 Venting DANGER: ▶ Do not reduce the vent pipe size. Do not put an elbow directly on top of heater. Failure to follow venting requirements may cause dangerous exhaust gases to enter living space. ▶ Minimum vent pipe diameter: 5 inches ▶ Minimum vertical vent height: 6 feet, with no elbows ▶ Establish 12 inch rise before any elbow The heater must be vented to the outside following all local ordinances and specifications for installing a gas appliance vent or chimney.
| Installation instructions Commonwealth of Massachusetts requires the use of a listed liner. Lining systems include approved clay flue lining, a listed chimney lining system or other approved material that will resist corrosion, erosion, softening, or cracking from exhaust flue gases at temperatures up to 1800 degrees F. The lining system must be listed for use with naturally drafting, draft hood equipped gas appliances. Follow local codes and refer to NFGC 54 and NFPA 58.
Installation instructions | 15 ESTABLISH A ONE FOOT RISE Fig. 11 Pitch roof [1] [2] [3] [H] Listed vent cap Lowest discharge opening Listed gas vent H (minimum) height from roof to lowest discharge opening [X] Roof pitch is X/12 [A] Minimum 6 feet (1,8m) 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.
| Installation instructions Bubbles are a sign of a leak. A combustible gas detector may also be used to detect for leaks. DANGER: ▶ If you have a leak, shut off the gas. Tighten appropriate fittings to stop leak. Turn the gas on and check again with a gas leak detection solution. Never test for gas leaks using a match or flame. Fig. 13 Installation of Gas Pressure Regulator Note: The 520 PN comes with a gas pressure regulator.
Installation instructions | 17 FOR NATURAL GAS Maximum Capacity of pipe in Cubic Feet of Gas per Hour for Gas Pressure of 0.5 Psig or less and a Pressure drop of 0.3 in Water Column (0.75mbar).(Based on a 0.60 Specific Gravity Gas) Btu numbers given in thousands. Copper tubing is prohibited for use with Natural Gas in the Commonwealth of Massachusetts and not recommended elsewhere. Follow boxed numbers for piping just one 520 PN (example: ¾” B.I. Natural Gas pipe for 20 ft (6.1m).
| Installation instructions 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 | 19 4.8 Measuring gas pressure Connecting manometer ▶ Shut off gas. ▶ Remove front cover and locate inlet gas pressure measuring point on the right side, see Fig. 14. ▶ Loosen screw from test point on the right side and connect manometer tube on test point. 4.9 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 5 4 2 1 3 6720608030-19.4Av Fig. 16 [1] [2] [3] [4] [5] Fig. 15 Plumbing connections and pressure relief valve shown with optional Webstone service valves 4.10 Recirculation application Since recirculation through the heater is not permissible, the following drawing is provided to outline a proper recirculation application using the BOSCH PRO water heater with an Ariston minitank.
Operation instructions | 21 WHAT TO DO IF YOU SMELL GAS ▶ Close gas valve. Open windows. ▶ Do not try to light any appliance. ▶ Do not touch any electric switch; do not use any phone in your building. ▶ Immediately call your gas supplier from a neighbors phone. Follow the gas supplier’s instructions. ▶ If you cannot reach your gas supplier, call the fire department. C. Use only your hand to push in the gas control buttons. Never use tools.
| Operation instructions ▶ Observe the pilot flame through the peephole. The gas valve button should be held down for at least 15 seconds with pilot burning before releasing. When the gas valve button is released, the pilot should continue to burn. - If the gas valve button does not pop out when released, stop and immediately call your service technician or gas supplier. - If pilot does not stay lit, repeat all steps.
Maintenance and service | 23 6 Maintenance and service 6.1 Maintenance intervals WARNING: ▶ Failure to perform recommended maintenance may result in complete failure of the unit over time. The warranty does not cover failures due to improper or insufficient maintenance. Fig. 24 5.5 Draining water from heater If there is a risk of freezing, proceed as follows: ▶ Remove the retaining clip from threaded bushing (Fig. 25, [pos. 1]). ▶ Remove threaded bushing (Fig. 25,[pos. 2]) from water valve.
| Maintenance and service plumbing lines. Position a bucket under the heater's water valve assembly to catch any water that may drain from the heater. Disconnect the inlet water pipe going to the back of the water valve. Disconnect the water pipe leading out of water valve to the heat exchanger. Do this by removing the retaining pin on water valve assembly and pulling the pipe free from the water valve. Loosen the two set screws at the bottom of the water valve where it connects to the gas valve.
Troubleshooting | 25 13. Disconnect all lines and drain all solution from heat exchanger. Properly discard of solution. 14. Position a container below the hot water outlet and connect cold water supply. Open cold water supply isolation valve and flush heat exchanger with clean water. 15. Shut cold water isolation valve and reconnect hot water supply to the water heater. 16. Reconnect electrical supply to unit, open water isolation valves, and return the unit to service.
| Troubleshooting 7.4 Pilot goes out during or after hot water use 1. Pilot outage during use typically results from the unit's safety overheat/high limit sensors interrupting the pilot circuit. The 520 PN does not have a thermostat. If inlet water is preheated, the unit will overheat, stopping the flow of gas. Plumb inlet with a cold water line only. 4. Close installer supplied cold water shut off valve (if none installed, install before proceeding). Open all hot water taps supplied by the heater.
Troubleshooting | 27 Watts brand 25AUB- ¾" or N35B -¾" pressure reducing/ regulating valves or equivalent are suggested. 5. If the inlet water temperature is not steady then the hot water temperature from the water heater will fluctuate. The 520 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 flow rate should be close to 2gpm, filling the jug in 15 seconds. With the temperature adjustment knob set all the way counterclockwise, the flow rate should be close to 4gpm, filling the jug in 7 seconds. If the flow rate is not adequate, inspect and clean the inlet filter screen (see chapter 6.2). original installer or a licensed gas technician to obtain this reading. 2. Confirm the incoming water pressure to the unit is above the required 30psi. 3.
Interior components and diagram parts list | 29 Follow instructions in chapter 5.5 to remove any additional water remaining in the watervalve and heat exchanger. 9 Interior components and diagram parts list 9.1 Interior components Fig.
| Interior components and diagram parts list 9.2 Fig.
Interior components and diagram parts list | 31 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 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.
LIFETIME LIMITED WARRANTY FOR BOSCH TANKLESS WATER HEATERS | 33 LIMITED WARRANTY. BTC SHALL NOT BE LIABLE FOR ANY INDIRECT, PUNITIVE, INCIDENTAL, SPECIAL, 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.
| Installer Checklist to be completed by installer upon installation 11 Installer Checklist to be completed by installer upon installation Serial Number (8 digit serial number is located on rating plate on right side panel) ___ ___ ___ ___ ___ ___ ___ ___ Gas Pressure Reading 1) Static Operating Water Pressure Building Water Pressure Range if on Well system Installing Company Installer name Address Phone Table 14 1) See Chapter 4.
| 35 Notes 520 PN 6 720 644 947 (2014/11)
