Bosch Water Heaters - Recent Questions, Troubleshooting & Support


That particular tankless water heater has hydro-generated ignition. In order for it to function, it requires a certain water pressure and velocity. You can try turning on the hot water in two location in your house to see if that gets it started. If it does, try getting a higher flow shower head, or removing the limiters in your faucets.

Bosch AquaStar... | Answered on Jan 31, 2019


as with all water heaters they need flushed once in awhile to get rid of sediment in the bottom of the tank . knowing this from the get go most of us never seem to get around to doing it . even myself but I do have a unit that is supposed to prevent this by the dip tube that was built in has circular action in the bottom of the tank

Bosch Water... | Answered on Jan 20, 2019


If there is not a clicking sound, it almost always means the main ignition or control unit (box with red and green lights and wires coming from it) is not getting the supply voltage. The voltage is supplied by a generator that is getting energy from the flow of water (the "hydro generator"). First disconnect the wire connector at the hydogenerator and check the voltage while water is running. The manual says you should read 1.6 VAC (I read 2.5 VAC). Make sure your voltage reader is on AC, not DC. If you have at least something like 1 VAC, then the next thing to check is the "microswitch" that allows the hydro generator voltage to reach the ignition unit. To check it, disconnect the other wire connector that is on the black wire coming from the hydrogenerator that is closer to the ignition unit. Then with the water running, stick a small screwdriver in the male plug side to short the two wires in order to bypass the microswitch (per Bosch tech support instructions). You should now here clicking and see the unit work. This is what happened with me and tech support said I needed to order a new microswitch and gave me a part number and telephone. But don't stop reading here. You can see the microswitch when looking up at the underneath of the unit. It's a small white 1x1 inch box-like shape held by 1 screw. After removing it, I noticed the microswitch had a removable cover (which is strange for a switch) and opened it to discover the internal switch can actually move inside because it "automatically adjusts" itself when it is first put in (it stays more firmly, but not rigidly in place when the cover is on). So you can mess up when putting it in. Don't bump it. It can easily get out of its working range of motion, which is why mine stopped working: it was a bad design to use this type switch in this application. So I slide the internal switch back close to the spring side ("default" position), put the cover back on, carefulyl screwed it in place, and now it works.

The purpose of the mechanical microswitch is to not allow the hydroenerator voltage to the ignition unit unless the "pushrod" has opened the main gas supply. It prevents clicking if there is no supply gas, so it is not needed (you can electrically bypass it with a splice) if everything else is working fine. But don't blame me if you do this and for some reason it ruins the more expensive ignition unit. The microswitch is turned on by the pushrod when the pushrod leaves it's default position. The the pushrod moves only about 2 to 3 mm when you turn on the water. You can see the pushrod when you unscrew the microswitch, and you can watch it move. The problem is that the microswitch mounting is not precise enough for the small pushrod movement and the pushrod's default position can change with age of the diaphragm or change in the grease. So their automatically adjusting microswitch that makes up for lack of precision in design and pushrod movement can stop working when the pushrod changes position. My unit was 2 years old.

Bosch 1600H-NG... | Answered on Dec 18, 2018


It would be on the thermostats.

Bosch Ariston... | Answered on Oct 26, 2018


iF YOU RAN OUT OF GAS, THE LINES MAY NEED TO BE PURGED OF AIR. dISCONNECT THE GAS FLEX AND TURN THE GAS ON TO PURGE THE AIR FROM THE LINE. dO THIS UNTIL YOU GET A STRONG SMELL OF GAS. aLSO, WHEN YOUR UNIT TRIES TO LIGHT, BUT THERE IS NO GAS, IT WILL TRY TO LIGHT THREE TIMES. aFTER THE THIRD ATTEMPT, THE UNIT LOCKS OUT. yOU MAY NEED TO RESET IT BY UNPLUGGING IT, OR IF IT IS HARD WIRED, JUST TURN THE BREAKER OFF FOR 10 SECOINDS AND THEN TURN BACK ON. tHIS WILL RESET THE GAS VALCE TO RELIGHT. gOOD LUCK!

Bosch Water... | Answered on Oct 03, 2018


Error code EA - No sparks for the electrodes
The ionization electrodes are not making sparks when water is flowing. There are many reasons for this problem and here are some; low gas pressure, fan speed is low, wire connections are loose, the air in the gas line, no gas.

Bosch Water... | Answered on Sep 08, 2018


1) BOSCH website shows error codes.
FO does not appear:
http://www.boschhotwater.com/HelpfulResources/TechnicalSupport/BoschAquaStarModels/2400ESTechSupport/Troubleshooting/tabid/1295/Default.aspx

2) I do not see FO error code listed on Internet search
Other FO questions at fixya seem to have no answer:
http://www.fixya.com/tags/error_f0_bosch

3) At this point, I would suggest calling a service technician.
While waiting for service, read manual cover to cover several times.

4) Your manual is valuable resource, and shows the word 'maintenance' and 'troubleshoot' frequently.
Tankless are maintenance heavy, and should be de-limed each year.
U-tube search "delime tankless water heater."

5) Also explore Bosch website for your manual and other valuable information.

6) When service tech arrives, ask that person for tips and tricks about your unit that will help you maintain your water heater.

7) All costs are energy. Install DIY tank-type gas water heater and avoid the whole headache.
http://waterheatertimer.org/How-to-install-gas-water-heater.html

Bosch Water... | Answered on Jun 10, 2018


hi julia
after checking on your bosch water heater error code e14
you can try to reboot your system but if code comes back you may need to find a plumber that knows your system to fix your fan system and clear your fault code. this is the site i got info from
http://www.jimsplumbing.net.au/bosch-hot-water-system/troubleshooting-guide/error-code-e14/
p.s. this site is not in the usa

Bosch Water... | Answered on May 20, 2018


when you turn on the hot water tap there is a pressure switch in the line that sends a signal to a gas solenoid to pass the gas and at the same time to the pizo to start the flame
I would have that pressure switched checked as it may be sticking ( internal contamination) or have dirty corroded points
as gas is involved I would suggest a gas technician do the jib
when you turn off the tap, that pressure switch is shut off so the gas is turned off at the solenoid and the pizo is stopped.

Bosch Water... | Answered on Apr 07, 2018

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