Troubleshooting | Bosch Appliances GWH 1600 H, GWH 425 HN manual

Troubleshooting

5 Troubleshooting

5.1 Introduction

Many of the questions customers ask regarding operation of this unit can be answered by following the troubleshooting steps outlined below. Visit our website at www.boschhotwater.com for more detailed troubleshooting. For best results, perform each step before proceeding to the next.

5.2Power vent motor runs all the time or intermittenly without water flow

1.The AQ4 power vent fan motor is equipped with a 45 second post purge cycle. The fan motor should continue to run for this length of time after the hot water flow has been shut off.

2.The power vent motor is flow switch activated. If the internal paddle inside the flow switch is jammed, it may constantly send a signal to turn on the fan. Shut off water supply to heater and drain. Remove flow switch from water heater piping by removing clips on both ends. Flush water through both ends of flow switch to free up internal paddle and clear debris. After flushing, shake flow switch up and down. The internal paddle should be heard moving freely back and forth.

3.Large amounts of water demand can create pressure drops throughout plumbing. This may allow for movement of the power vent flow switch and activate the fan. Activated sprinkler systems or flushed toilets are common causes for this symptom. Consult a plumbing professional for the use of check valves to prevent unintentional water flow through the heater.

4.In buildings with excessively high water pressure, a condition known as “water hammer” may exist. This condition is caused by a combination of high water pressure and the abrupt closing of a faucet valve or internal washer/toilet valve. This instant change in flow results in an instant change in the internal pressures in the pipe, which then sends a shock wave through the pipe. This physical shock will shake, rattle or cause a loud bang in the plumbing which we refer to as “water hammer.” Such a shock wave may cause movement of the power vent flow switch which will activate the fan. Consult a plumbing professional for the use of a pressure reducing valve, expansion tank or water hammer arrestor to combat this condition.

5.3Pilot will stay lit when manually lit (1600P and 425PN) or will not spark automatically with hot water flow (1600H and 425HN)

1.Check the linear safety spillage switch reset button to see if it is tripped (See Section 2.6). Overheating or loss of power to the unit will trip the safety spillage switch and stop the flow of gas.

2.Check the entire pilot safety circuit (including the safety spillage switch) for loose or dirty connections (See Fig 8). Clean any corrosion evident with a pencil eraser or light sandpaper.

3.Pilot flame is weak or dirty. Consult water heater installation manual for instructions on cleaning the pilot assembly.

5.4Pilot and/or burners go out during hot water use

1.Inspect entire vent system for blockage or obstruction. Ensure the back draft flapper installed on the power vent hood swings freely.

2.Verify power vent fan operates with water flow. If not, verify wire connection from flow switch to fan motor. Clean cold water inlet filter and verify flow rate through the water heater is adequate enough to activate the flow switch. If flow rate is more than 0.5 GPM, then flow switch may be defective and should be replaced.

3.If heater is newly installed, verify power vent fan motor is not installed backwards (See Fig 4).

4.Ensure power vent motor is mounted as close as possible to the VH1-4 vent hood. Mounting the power vent motor directly on top of or close to the water heater, may result in lifting flames and pilot outages.

5.5Noise when power vent motor is running

1.Ensure power vent motor is mounted level with motor shaft horizontal or premature motor bearing wear may occur.

2.Ensure power vent motor is mounted using the supplied vibration mounts or premature motor bearing wear may occur.

3.Remove vent pipe connection from water heater to power vent motor. Inspect internal fan wheel for broken fins. If any damage is evident, order online or call Technical Support (800) 642-3111 for a replacement wheel kit.

10	AQ4 Manual

GWH 425 PN, GWH 1600 P, GWH 1600 H, GWH 425 HN specifications

Bosch Appliances have long been synonymous with innovation and reliability in the realm of home comfort solutions. Four notable models in their range of gas water heaters are the GWH 425 HN, GWH 1600 H, GWH 1600 P, and GWH 425 PN. Each unit is developed to meet diverse user needs while providing the highest levels of efficiency and performance.

The Bosch GWH 425 HN is a high-capacity unit catering to larger households or commercial environments. With an impressive heat output, this model ensures a consistent hot water supply when needed. Key features include advanced combustion technology for enhanced efficiency and reduced emissions, making it an environmentally-friendly choice. Its compact design allows for flexible installation options, fitting seamlessly into tight spaces. Additionally, the unit is equipped with an intelligent control system that optimizes performance based on usage patterns.

Moving on to the Bosch GWH 1600 H, this water heater is perfectly suited for smaller homes and apartments. It combines user-friendly operation with energy-saving capabilities. This model utilizes a unique modulating burner system that adjusts the flame intensity according to water demand, significantly lowering energy consumption. Furthermore, the GWH 1600 H incorporates a built-in safety system that ensures optimal operation under varying conditions.

The Bosch GWH 1600 P offers a similar capacity as the GWH 1600 H but with added digital functionalities. Users can expect advanced temperature settings and real-time monitoring through an intuitive digital display. This model prioritizes ease of use, allowing homeowners to customize their hot water experience effortlessly. The GWH 1600 P also reflects Bosch’s commitment to durability, featuring robust construction suitable for various environmental conditions.

Lastly, the Bosch GWH 425 PN is another versatile choice for those needing robust hot water production. It shares many characteristics with the GWH 425 HN, like high efficiency and smart technology. However, it distinguishes itself with innovative low-NOx technology, reducing nitrogen oxide emissions to meet stringent environmental regulations.

In summary, Bosch's GWH 425 HN, GWH 1600 H, GWH 1600 P, and GWH 425 PN represent a diverse selection of gas water heaters designed to suit different household needs. Whether it’s for a larger family or a compact apartment, these models provide efficient and reliable hot water solutions while employing advanced technologies to minimize environmental impact. With their focus on quality and customer satisfaction, Bosch Appliances continues to lead the way in the hot water industry.