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Bosch 1600H Tankless Water Heater Troubleshooting


Bosch 1600H Tankless Water Heater TroubleshootingIf you’ve run across problems with your Bosch 1600H Tankless Water Heater than this economy is probably encouraging you to get on the do it yourself train. This article details the specifications of how to solve a variety of problems that may happen with this Bosch hot water heater. Examples of things that may go wrong are: Temperature being too hot or cold, problems lighting the pilot or keeping it lit, low pressure, blockages, noise pollution and many other things. As always if you are unable to complete these repairs in a safe manner please consult a professional.

PROBLEM: Water is too hot.

SOLUTION: First make sure that the power knob is set to the small flame position and that the temperature knob is on the appropriate setting. Try increasing the rate of water flow, make sure that all external outlets such as faucets are clean and have no blockages and that the inlet filter is clean. High mineral deposit rate inside the water connections can cause the water temperature to boil and become too hot. If this is the probem it is recommended that you call a professional.
Bosch 1600H Tankless Water Heater
PROBLEM: Yellow Flame.

SOLUTION: Make sure that the burners are clean as well as all the ventilation systems and air intake.

PROBLEM: Low hot water pressure.

SOLUTION: This unit can only run one application at a time, if too many taps are open at once it will make the water flow very poor. As with temperature, mineral content can effect water pressure and you should call a professional to solve this problem if that is the case. Be sure that all showerheads and faucets are clear of obstruction. Check that the water pressure of the unit is above 30 PSI, if it’s not you can do the following test to check the flow rate: 1. Shut off the cold water supply and disconnect the hot water supply. 2. Open the cold water supply and put a container underneath to check the water. 3. Turn the temperature knob all the way clockwise and take a reading, it should be 2 GPM. 4. Now turn the temperature knob all the way counterclockwise, the reading should be 4 GPM. If you don’t get those readings make sure the inlet filter is clean.

PROBLEM: Burners go out when you are using hot water.

SOLUTION: Check to see if temperature limiter and flue gas are tripped. This can be caused by using pipes that are too small or by improperly using elbows which restrict the ventilation system. You can try turning the temperature knob down to reduce the amount of cold water that will be used to cool the hot water. Make sure the water pressure is no less than 30 PSI. Check for plumbing crossover, the test to do this is detailed in the section on “low water pressure”. You can also check the hot water flow rate which is mentioned in more detail in the “low water pressure” section as well.

PROBLEM: Noise when heater is running.

SOLUTION: Do an inspection of all the outlets and connections outside of the unit and make sure there are no blockages. High mineral content can be problematic for any function of a water heater and may also increase the noise output. If your unit is too noisy it may be due to the fact that the flow is too high. To test the flow see the section detailing “water pressure”.

PROBLEM: Pilot lights but burners do not go on.

SOLUTION: Make sure the pilot flame is the right color, if it is yellow please refer to the “yellow flame” section. Make sure the flame sensor is clean and operating properly. Check to see if all the water flow connections are running smoothly without obstructions. Check to see that the wiring for the burner electrovalve is correct and make sure there is no corrosion on the terminal. You can clean the terminal by removing the spade connector and using a pencil eraser.

PROBLEM: Water is not hot enough.

SOLUTION: Make sure that the power knob is turned to the highest flame setting and that the temperature knob is adjusted accordingly. Check for blockages on any outlets that are external to the hot water heater. Make sure the water valve is clean so that it will properly open the gas valve. Take a reading of the gas pressure to ensure that it isn’t too low. The flow on one of the taps may be too high, make sure the settings are within the abilities of the unit. You can also test for a plumbing crossover by opening all the hot water valves on the unit and seeing if any water comes out. If there is water coming out than you will need to consult a plumber.


  1. GWH 1600 H LP- The switch lights don’t go on in either position. The pilot light doesn’t light, when the hot water tap is turned on. It also will not light when lit with an outside flame,ie: match, lighter etc. All screens are clean, no blockages, or plumbing crossovers. Before a total failure in heating the water, the water temperature would fluctuate quite a bit during use.

  2. i have a 1600 p hasent had 50 gallons of water run thru it, the piolot will not stay lit. ive had numerous techs look at it but nobody has fixed it yet, its got a full 3/4 pipe running to it correct w/c bosch is a rotten outfit, wont standby what they sell.

  3. I have a 1600h that I installed at my cabin when they first came out. It is the most frustrating unit I have ever dealt with. The unit is installed at 7000′ on the West Slope of Colorado. I have an 80 gallon propane tank running it. In warm weather it is 80% reliable. We turn the hot water on at the sink in the bathroom and wait for hot. We hear the click of the igniter but until it catches and ignites we have to turn it on and off many times. Once we get hot, then we can turn the shower on and take a shower. The colder it gets outside the more likely it is not to work. Recently I tried unsuccessfully for an hour to take a shower that I desperately needed. I finally ended up replacing the whole house water filters ( the water is dirty and has to be filtered) to get it to work. We have about a 25′ run to get to the kitchen sink. We seem to never be able to get hot water here. I suspect there are a number of variables at play here. 1. The propane tank outside doesn’t get warm enough to generate enough gas to get it going. 2. Due to the reduced water pressure ( due to filter or other reason) the unit will not fire up.

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