Operation, Maintenance, Draft test | Bosch Appliances GWH 425 PN

Operation

3 Operation

3.1 First time start up

It is important to verify proper operation of the power vent motor before commissioning the system:

1.Slowly turn on cold water supply and check for any leaks at newly installed flow switch and piping.

2.Plug power vent motor into 120VAC outlet.

3.With the gas supply to the water heater turned off (see water heater manual) turn on a hot water tap. The power vent motor should come on. Verify the back-draft flapper is open and air is being blown out of the power vent hood. If not, see the troubleshooting tips in Chapter 5.

4.Turn off hot water tap.

Note: 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.

5.Open gas supply to the water heater and follow the lighting instructions in water heater installation manual.

3.1.1 Draft test

1.Check for proper combustion and ensure there is no spillage by holding an recently extinguished match or other visible smoke source in front of the draft divertor. The smoke from the extinguished match should be quickly sucked into the opening and up the exhaust venting. If the smoke is blown back, there is a blockage in the vent or the vent motor is not operating properly.

3.1.2 Safety interlock test

1.Open the gas supply to the water heater.

2.Block the back draft flapper from opening from the outside.

CAUTION: The metal of the back draft flapper will be hot when conducting this test.

3.Turn on the hot water supply to allow the burner to activate. Hot flue gasses will spill from the draft diverter momentarily. In less than three (3) minutes, the linear spillage switch should trip, opening the the heater safety circuit and halting the flow of gas to the heater.

NOTE: If spillage switch does not shut off the gas, check that you have made the proper safety circuit connections. If the switch still does not trip, contact Bosch Water Heating.

4.After the burners shut off, turn off hot water supply and wait 2-3 minutes...then push the reset button on the linear spillage switch.

5.Depending on model, light the pilot or run hot water and repeat Safety Interlock Test, (Step 1-4)

6.Ensure back draft flapper moves freely andcloses properly before operating once test is complete.

4 Maintenance

The vent system must be inspected at regular 3-month intervals. Points of inspection are as follows:

1.Screened opening of the vent hood should be free from foreign material and cleaned as necessary.

2.Check all vent system connections for leakage and reseal where needed with high temperature silicone sealant. If any vent pipe component shows signs of deterioration, replace immediately.

3.Inspect proper closure of the back draft flapper accessory. If the flapper does not properly close, there is a risk of freezing air crossing the heat exchanger that may cause the pipes to freeze and burst. This condition is not covered by the water heater warranty. See Fig. 11A for a properly closed back-draft flapper.

4.Conduct safety interlock test and operation of backdraft flapper once a year (Chapter 3.1.2).

Fig. 11A Properly closed backdraft flapper

Fig. 11B Improperly closed backdraft flapper

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.