20 Most Recent Bosch AquaStar 2400ES-NG - Page 2 Questions & Answers

possibly needs descaling and or pump needs replacing

you must read your owner manual read the troubleshooting section, and if the problem persist, get the website with your supplier and connect via ONLINE chat with technical personal in order to Help you and fix it. God bless you

http://www.bosch-climate.us/files/201109162006340.GWH2400ES_English_10_2007.pdfsounds like the inlet water screen needs to be cleaned or the unit is scaled up with minerals. see attached link to manual

On this unit it requires cleaning of water inlet valve every 3 to 5 years and it may need a kit woth new o rings.

1) Live answer Feb 2013:http://waterheatertimer.org/pdf/Bosch_EA_error_code_troubleshooting.pdf2) Call Bosch1-866-642-31983) Call service technician.4) Fix any brand tankless water heater problem yourself, same day, for $350http://waterheatertimer.org/How-to-install-gas-water-heater.html If you need further help, I’m available over the phone at https://www.6ya.com/expert/gene_9f0ef4df2f9897e7

Here is the troubleshooting guide for the A7 code:http://www.bosch-climate.us/files/201109161634300.TWH-G2-31_A7_error_code_troubleshooting.pdf

Before calling service technician, copy following links for troubleshoot resources:http://waterheatertimer.org/pdf/Bosch_E9_troubleshooting.pdfhttp://waterheatertimer.org/Troubleshoot-Bosch-Tankless-water-heater.htmlYou should delime water heater once per year to prevent many common error codes.http://waterheatertimer.org/pdf/Delime-tankless-water-heater.pdf If you need further help, I’m available over the phone at https://www.6ya.com/expert/gene_9f0ef4df2f9897e7

Code EL does not show on typical Bosch error code list.Maybe you have E1 ?? Or Bosch has some other error codes not listed.http://waterheatertimer.org/pdf/Bosch_E1_troubleshooting.pdfhttp://waterheatertimer.org/Troubleshoot-Bosch-Tankless-water-heater.htmlhttp://www.bosch-climate.us/support-center/technical-support/ If you need further help, I’m available over the phone at https://www.6ya.com/expert/gene_9f0ef4df2f9897e7

Does it happen to any other fixture? If not, it's most likely your shower valve and not heater.

it must not be on properly or not tightened properly

Model????? The 635Es, 250SX and 2400E are same. The 2400ES and 2700ES are World 2 heaters. Any error codes as I can't imagine this problem w/o codes. Flow initiated but you have spark. Is there any ignition? If so flame rod may be bad and not reporting ignition. Igniter sets on some early 2400/2700 have proved to be bad. Water pressure has zero to do with this. If you have an EC or EA code you have gas problems (meter, line size/length or gas valve). Also if 3005 or 3007 Software you can pull the last 5-10 error codes from Controller.
You need to call Bosch and get an RSA out there. This is a gas appliance that if you screw up can destroy your house. FYI any water in the gas valve condemns it. It will not dry out and work correctly. Is the fan running at ignition and/or purge? Any Controller errors require replacement. You have 2 years on parts warranty from installation date so don't screw around trying to DIY. Warranty Labor is not covered.
Flue obstruction? If you used the AQ3 installation Kit you have the wrong termination box to prevent freeze up and/or water penetration You need the Z-Vent drop nosed termination. Look for a fine tan dust in the fan intake (brown plastic) the intake throat or in passageway to the gas valve. Call Bosch unless you're a Gas Tech this is beyond you.

You must have a bad fuse in the control board

Before calling service technician, call Bosch. 800-642-3111
E7 is not shown as common error code.
Error codes are considered start-point for troubleshooting.

Open following links for general Bosch troubleshoot resources:
http://waterheatertimer.org/Troubleshoot-Bosch-Tankless-water-heater.html
Common error codes:
http://www.boschhotwater.com/HelpfulResources/TechnicalSupport/BoschAquaStarModels/2400ESTechSupport/Troubleshooting/tabid/1295/Default.aspx
Service bulletins for reading how to fix tankless yourself:
http://www.boschhotwater.com/HelpfulResources/TechnicalSupport/BoschAquaStarModels/2400ESTechSupport/ServiceBulletins/tabid/1300/Default.aspx

Had same problem on my five year old water heater (ec error). Didn't figure it was a gas supply problem after five years but double checked to see if the gas bill was paid. It was.

Cleaned the contacts on the two sensors that are clamped to copper pipes inside. Still had error after powering up. Held the error button in for about five seconds, and the blinking EC code went away.

Before calling service technician who has service manual and can test which part has failed, open following links for troubleshooting resources including steps below and phone number for Bosch:
http://waterheatertimer.org/Troubleshoot-Bosch-Tankless-water-heater.html
http://www.boschhotwater.com/HelpfulResources/TechnicalSupport/BoschAquaStarModels/2400ETechSupport/Troubleshooting/tabid/1131/Default.aspx

Clean inlet filter
Check all faucets for clear pathway
This unit does not work with preheated water (solar assisted)
Incoming water above 70 degrees, avoid restricted faucets
Check that both temperature sensors are making contact and firmly mounted on respective cold and hot pipes.
Descale heat exchanger
http://www.boschhotwater.com/Portals/7/TechBulletins/TWH-G2-13_Descaling.pdf

Yes. Contact Bosch.
Error codes are considered start-point for troubleshoot.
http://waterheatertimer.org/Troubleshoot-Bosch-Tankless-water-heater.html

Tankless are complex electronic machines.
If on-site plumbers cannot figure out problem, then you need trained service technician with a service manual for your specific product, who can ohm-test the electronics.
Bosch will have a list of trained service technicians. And maybe Bosch has another step for fixing problem yourself.

Fix most tankless problems yourself, same day, for $330.
http://waterheatertimer.org/How-to-install-gas-water-heater.html

Before calling service technician, open following links for troubleshoot resources including common error codes, Bosch contact information, link to service manuals, and possible product manual
http://waterheatertimer.org/Troubleshoot-Bosch-Tankless-water-heater.html
http://www.boschhotwater.com/HelpfulResources/TechnicalSupport/BoschAquaStarModels/2400ESTechSupport/Troubleshooting/tabid/1295/Default.aspx

Call Bosch 800-642-3111
Multiple error codes can mean PC board failure.
AF might be A9, but not sure.
EA is 'no flame ionization detected with water flow'

1. Verify that all manual gas shut off valves are open.
   
2. Check gas type.
   
3. Reset error code and open a water tap to cycle the heater in an effort to purge air on new installations. Cycling hot water tap on and off multiple times may be necessary. If heater still faults with EA error code, have a licensed gas technician properly purge air out of the gas line leading to the water heater.
   
4. Check three wire connections to ignition group on the lower front of the heat exchanger are secure.
   
5. Check gas pressure.
   
6. Check venting specifications are met. Improper venting may cause premature failure of the flame sensor rod.
   
7. Check that the minimum power fan speed has been adjusted to the proper value.
   
8. Observe inside the viewing window of the heat exchanger when a hot water tap is opened. Sparking should be followed by a steady blue flame. If flame is unstable or yellow with proper gas pressure.