Bosch Water Heaters - Recent Questions, Troubleshooting & Support


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 2 days ago


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


the tank is possibly full of gunk and the thermostat is not sensing the request for hot .flush tank if you can thru the bottom drain a few times if it is bad enough that ou get no water out then only option is to replace with a new unit

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


The Bosch Hydropower units have poor electrical design, anyway assuming the heater is working properly, I would get it serviced for this that is <(TURN OFF GAS>), backflush water circuit, just unplug in and out water pipes and connect a hose to the outlet its easy enough to find a fitting or something, but you may need to bend the pipes around a little but do not hurt them!, the crud buildup in the pipes will reduce your efficiency like if you use it with unfiltered rain tank water you would want to clean it about every 5 years on the other hand if you have hard water as in bore water then I dont know but I think calcium buildup will be your problem. hard water clogs up everything, disassemble and clean out water inlet manifold, there is a mesh screen in there, on mine it was in bits all through the ports clogging everything up. Now if needed clean over the whole unit with compressed air to spruce it up and reduce fire hazard or if your diy then it's nice to clean things before working on them imo. Don't ask me what all that would cost! You don't need to mess round with the gas side that's all fine. Now here's what you do to fix em, this is for a Bosch Hydropower 10H but I assume it probably applies to the other hydropower models too. Ok for those wanting more information the water flow runs the electronics @ 1.5v DC wich charges the high voltage pilot igniter but it also runs the 2 solenoids for the pilot gas circuit and that pilot circuit operates the diaphragm for the main gas valve. The thing is those 2 little solenoids are grounded through the whole unit, if you look it,s not great, so what I did was add a piece of wire say 5 amp should be heaps, now connect the wire to the fixing point for ground next to the electrical box and now connect the other end to one of the chunky screws that holds on one of the gas solenoids(DON'T REMOVE SOLENOIDS UNLESS YOUR REPLACING THEM THEY ARE VERY FRAGILE AND DON'T ABSOLUTELY DON'T UNSCREW THE SCREWS ON THE LITTLE COLORED PLASTIC BIT, That said I used the green one at the back, don't worry it wont leak gas as long as you only remove one screw but of course (>TURN OFF THE GAS<). Tighten up all the screws, again it does'nt hurt to go over the unit and check all the screws and bolts, there is one screw for calibrating the sliding knob also. And that's it turn on the gas and water and go test your brand new water heater! More info, you can test the generator with a multimeter, just unplug it and test the voltage with the water running through it obviously. Mine was about 1.6v You could also test the resistance of the gas solenoids with and without extra wire, etc. Fyi there is a brass screw about half way up on the left side of the unit facing out that I use to bleed the gas line, at least that's what I use it for. Just unscrew it a bit while its trying to light you just have to flick the switch a few times until the gas comes through then screw it up again. Also it doesn't hurt to go over everything with some soapy water in a sprayer to check for gas leaks especially if unit is old or if you can smell gas, I imagine if there was a gas leak inside the cover that would cause some issues. Anyway you wont believe how well it works after this mod, it ALWAYS starts as long as u have gas, it will stay lit at pretty low flow levels so you can mess round with the cold tap and it wont cut out to a point, I used to just have the cover off cos I was always messing with it trying to get it to light or tuning the knobs man it drove me nuts. Now I just leave it at the mid point between my summer and winter settings. I also disconnected the lights to help it work better but I think that's overkill. You don't really need to blast the hot tap anymore if you have enough flow it will just come on. Oh and if you still need or want to better control the temps then get plumber to install a tempering valve. The flow control knob I just have cracked open but I think If you have not enough pressure at hot tap you could open flow more and also turn up the heat more. P.S. my 10H was about 10yo when I serviced it. The Wizz.

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

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