CLOGGED HEAT EXCHANGER - A.O. Smith BTH-199 BTH-199 100 Gallon 199,000 BTU Cyclone Xi[REG] Commercial Gas Water Heater

Hear is a list of possible causes for running out of hot water.

• Water temperature is set too low. Increase the temperature to approximately 125-130 F.
• Reduced the water flow when the water filter or fixture aerator are clogged.
• If there is a plumbing crossover, cold water is mixing with the hot water. One of the reasons for the plumbing crossover is if the single-lever mixing valve was installed, and it failed.
• Gas valve does not provide enough pressure; either due to the low gas pressure or if it is not open fully. Is the gas line sized correctly?
• Sediment and limescale build-up inside the heat exchanger. You might want to use the descaling procedure and flush all the deposits. The scale deposits act as an insulator preventing the heat exchanger to transfer the heat to water.
• Is venting system clean of the debris and does it provide enough fresh air for proper combustion?

look for leak --clogged line --or problem with pump

If the heater is more then a few years old the heat exchanger is probably corroded. Air flow from the blower motor can't squeeze thru the exchanger fins and causes loud vibrations. It can sometimes be cleaned but usually requires replacement of the heat exchanger. If you are not familiar you should definitely have a professional sevice the unit. Continued use in its current state can cause many other issues. Be prepared because the heat exchanger is the most expensive part of the heater and the most difficult to replace

Mechanics do the same thing. Let's play a game... i'll guess what is wrong.... and you pay for it till i get it right! :)

Before calling service technician, copy following link for troubleshoot resources:
http://waterheatertimer.org/Troubleshoot-Rheem-Tankless-water-heater.html

C4 can range from failed PC Board to lime build-up inside heat exchanger
Error 15 is 'heat exchanger is too hot', clogged heat exchanger, restriction in cold water inlet, temperature set point too high.
If you recently changed temperature setting, then that might be cause.
Tankless require monthy-to-yearly maintenance to avoid common error codes.
Delime tankless and clean water filter, keep temperature low.
Never install tankless water heater is best way to avoid complications of expensive water heater that is maintenance heavy, hard to diagnose, expensive to fix, etc.
Never expose tankless to more than 11 grains hard water.
http://waterheatertimer.org/pdf/Rheem-CondensingTankless-maintenance-2012.pdf
http://waterheatertimer.org/pdf/Rheem-De-lime-tankless.pdf

If you need further help, I’m available over the phone at https://www.6ya.com/expert/gene_9f0ef4df2f9897e7

The OHL is not for sale due to a couple of reasons. If the heat exchanger has a hot spot it will melt the OHL making it useless. The OHL is just a large fuse. Rheem will completely warranty (if within date range) if the OHL or heat exchanger has problems. Bypassing the OHL is very dangerous and could result in a house fire since the appliance is mounted to a wall. I would suggest scrapping the copper heat exchanger for cash. That about all its worth in the condition its in.

Before calling Rheem or service technician, open following link for troubleshoot resources including error codes, Rheem chat, typical required maintenance manual, and possible product manual:
http://waterheatertimer.org/Troubleshoot-Rheem-Tankless-water-heater.html
http://waterheatertimer.org/pdf/Tankless-maintenance.pdf

Error codes are start point for troubleshoot.
Error 14 is 'overheat wrap fault.'
This can include venting problem, failed heat exchanger, bad safety circuit, gas problem.
Rheem does not have a service manual posted for this specific problem.

Additional information: Tankless water heaters consume large amounts of gas during combustion. The combustion burns away hydrogen and the remaining poisonous byproduct is vented into the atmosphere at each home day and night.
Byproduct includes acidic water vapor that condenses along the vent pipe and drips back down vent.
Each tankless vent pipe has a drain line that directs acidic water into household drain.
If this drain line becomes clogged, or if vent was not installed correctly, then water drips down into heat exchanger and can erode or crack exchanger.
The typical maintenance manual above shows steps that can solve many tankless problems before they happen.

Before calling Rheem or service technician, open following link for troubleshoot resources including error codes, Rheem chat, typical required maintenance manual, and possible product manual:
http://waterheatertimer.org/Troubleshoot-Rheem-Tankless-water-heater.html
http://waterheatertimer.org/pdf/Tankless-maintenance.pdf

Error codes are start point for troubleshoot.
http://waterheatertimer.org/pdf/ErrorcodeTroubleshooting.pdf
Error 14 is 'overheat wrap fault.'
This can include venting problem, failed heat exchanger, bad safety circuit, gas problem.
Rheem does not have a service manual posted for this specific problem.

Additional information: Tankless water heaters consume large amounts of gas during combustion. The combustion burns away hydrogen and the remaining poisonous byproduct is vented into the atmosphere at each home day and night.
Byproduct includes acidic water vapor that condenses along the vent pipe and drips back down vent.
Each tankless vent pipe has a drain line that directs acidic water into household drain.
If this drain line becomes clogged, or if vent was not installed correctly, then water drips down into heat exchanger and can erode or crack exchanger.
The typical maintenance manual above shows steps that can solve many tankless problems before they happen.

Before calling service technician, open following links for Bosch troubleshoot resources:
http://www.boschhotwater.com/HelpfulResources/TechnicalSupport/BoschAquaStarModels/2400ESTechSupport/Troubleshooting/tabid/1295/Default.aspx
http://waterheatertimer.org/Troubleshoot-Bosch-Tankless-water-heater.html

Error codes are start-point for troubleshoot.
A7 is temperature sensor fault.
This can be bad wiring, corroded wiring, failed sensor, very high temperatures due to other part failure.
Other cause can be water filter clogged, lime and scale inside heat exchanger, faucet aerators clogged, or combination of problems listed.

Each tankless manual across all manufacturers suggest maintenance schedule: clean water filter monthly, delime heat exchanger yearly, and yearly service of burner and other parts by trained service technician which can address cause of most error codes, and might solve some problems before they happen.

If tankless becomes chronic issue, solve problem yourself, same day, for about $350.
http://waterheatertimer.org/How-to-install-gas-water-heater.html

61 code is a fan motor abnormality. It typically indicates the fan is damaged and needs to be replaced. It can be caused by water leaking onto it from the heat exchanger.

The heat exchanger isn't difficult to replace, but it is confusing if it's your first time doing it. I'd recommend calling Noritz for assitance.