20 Most Recent Bosch 1600H-NG Natural Gas AquaStar AquaStar Natural Gas Tankless Water Heater... - Page 5 Questions & Answers

Check the gas valve ,and pcb

might have a flow bypass valve.? check out the OM LINKED Worcester greenstar 40 cdi conventional installation and servicing

I would look on the Bosch wed site for this information .

Sounds like a faulty pcb,

Depending on what part is being replaced, it may sound high but the gas valve is about $300 and the water valve about $200 street price. its also a time consuming job.

Highly recommend a "plumber" that is different or new to you. Realize that if you must find one by phone, that would be much less desirable that going in person to the business and talking to the owner before hiring the job done. "Not all plumbers created equal." God bless your efforts.

Manual might help: http://waterheatertimer.org/pdf/Bosch_10P-water-wizard.pdf If you need further help, I’m available over the phone at https://www.6ya.com/expert/gene_9f0ef4df2f9897e7

http://waterheatertimer.org/pdf/Bosch_10P-water-wizard.pdf If you need further help, I’m available over the phone at https://www.6ya.com/expert/gene_9f0ef4df2f9897e7

diverter valve may not be seating on ch side letting water to pass.

Yes you need to delime tankless each year.http://waterheatertimer.org/pdf/Bosch_Descaling-heat-exchanger.pdfhttp://waterheatertimer.org/pdf/Rheem-De-lime-tankless.pdfContact Bosch for exact repair information. My records show following number for tankless gas: 800-642-3111 http://waterheatertimer.org/Troubleshoot-Bosch-Tankless-water-heater.html If you need further help, I’m available over the phone at https://www.6ya.com/expert/gene_9f0ef4df2f9897e7

try looking at this. might be a thermostat problem, usually a cheap fix and found on feebay. https://www.bosch-climate.us/files/201009031229480.635ES_English_11.2007.pdf