6.Verify pilot flame completely engulfs the thermocouple tip. If pilot is too small, clean pilot orifice (see chapter 5.3).
7.If the water has a high mineral content, the heat exchanger may be scaled internally. This restricts the water path, causing the water to over heat which shuts all gas off to the heater. Instructions for descaling the
heat exchanger are available at www.boschhotwater.com.
8.If steps 1 through 7 do not correct the problem, then confirm that the gas pressure is adequate. Ensure gas pressure is in accordance with manufacturer's specifications (see Chapter 3.9). A gas pressure reading is needed to proceed further. Contact your original installer or a licensed gas technician to obtain this reading.
6.5Burners do not light with water flow
1.Verify the pilot is lit
2.Verify the gas control slide button is between the 1flame and 3 flame positions.
3.Verify the cold water supply is connected to the right side of the heater.
4.Close installer supplied cold water shut off valve (if none installed, install before proceeding). Open all hot water taps supplied by the heater. Wait 5 minutes and check all taps. Any water running is a sign of a plumbing crossover. Consult a local plumber or service person for help in correcting a plumbing crossover.
5.Verify flow through the water heater is sufficient. Turn temperature adjustment knob all the way clockwise. Fully open a hot water faucet and fill a quart container. If the container fills in 30 seconds or less, the flow rate (1/2 gallon per minute) is sufficient to activate the heater.
6.Inspect the water path outside of the heater for obstructions. Make sure all outlets (i.e. showerheads, faucet aerators and whole house filters) are clear of debris. Also, the water heater's inlet filter screen should be inspected and cleaned (see chapter 5.2).
7.The water valve assembly, which actuates the burners, requires periodic maintenance (every 2 - 5 years depending on water quality and use) (see chapter 5.2).
6.6Hot water temperature fluctuates at tap
1.Close off installer supplied cold water shut off valve (if none installed, install before proceeding). Open all hot water taps supplied by the heater. Wait 5 minutes and check all taps. Water running is a sign of a plumbing cross-over. Consult a local plumber or service person for help in correcting a plumbing crossover.
2.Check for a clogged inlet water filter screen (see chapter 5.2).
3.Hot water is very hot out of the tap, requiring a lot of cold water to be added with it in order to attain a useable hot water temperature. The addition of too much cold will overpower and slow the flow within the tankless water 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 need for cold water mix by setting the gas slide control button towards the single flame position for lower hot water temperatures. If the problem persists, go to www.boschhotwater.com for a more detailed service bulletin on this problem.
4.The GWH 1600 P is designed to modulate gas flow to the burners when water flow varies. If the water pressure in the home is erratic and the water flow is not consistent while a tap is opened, then the temperature of hot water will fluctuate. The minimum water pressure for the home should be 30psi or greater. For installation on a private well system with the use of a pressure tank, the lowest pressure range setting recommended is 30-
50psi (2.07-3.45 bar). The use of a pressure reducing/ regulating valve before the water heater (directly after pressure tank on well systems) is an effective way to maintain constant water pressure to the water heater. 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 GWH 1600 P 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.If the inlet water temperature to the water heater is above 70°F, the heater may produce outlet temperatures that are too hot for most users. A temperature balance shower valve can automatically mix in cold water to reduce such hot water temperature. This can slow the flow within the tankless water heater, decreasing it below activation point, which shuts off the burners. In the event of any temperature instability with the use of a temperature balance shower valve, refer to shower valve manufacturer's instructions for internal adjustment setting. An adjustment should be made to minimize the amount of cold water the valve is adding.
7.The gas pressure also needs to be stable and adequate. Ensure gas pressure is in accordance with manufacturer's specifications (see chapter 3.9). A gas pressure reading is needed to proceed further. Contact your original installer or a local certified gas technician to obtain this reading.
8.A water valve, which has not been serviced, may be struggling to keep the gas valve open. The water valve requires periodic maintenance (every 2-5 yrs depending on water quality and use) (see chapter 5.2)
