20 Most Recent Bosch AquaStar Indoor Natural Gas Tankless Water Heater with Vent Hood #125 - Page 4 Questions & Answers

Sounds like the 125X unit. This unit has a brass water valve. Be sure to service the water valve every 1-2 years. It is the most common cause of the 125 series heater not working. There is also an inlet filter screen on the water valve that needs to be cleaned or replaced.

Where the pilot light goes into the burner, there is a very small tube that goes to the gas valve. The side near the burner, take the tube off and DO NOT LOOSE THE orifice (it looks like a derby hat)! The orifice is likely dirty.

Service the water valve. The pin is not returning to the off position. The water valve should be serviced every year or two.

Often this is a problem of gas piping. It is likely too small. The pipe should be 5/8" copper or larger, or 1/2" Black iron or larger. The gas regulator (if it is LP) will need to be turned up from 9 inches water column to 11 inches water column when all gas appliances are operating.

water from heater is no longer hot

The simple answer to reducing 12V ac to 10V ac is to use a transformer, however, noting that your question is in relation to a water heater, I am assuming that you are troubleshooting and have found a voltage of 12V that you expect should be 10V.

If this is an AC power source, normally, a voltage variance of this magnitude (around 15%) would not be considered significant. The voltage itself would have been transformed down from the supply voltage (via a transformer) and a + 15% overvoltage on the grid would not be uncommon in many lands, particularly outside of peak load periods. This could account for the variance that you have identified and would be a 'normal' operating condition.

On the other hand, if you are troubleshooting electronic components on a printed circuit board you might actually be measuring a pulsed DC signal and will obtain spurious readings on both AC and DC ranges on a standard multimeter. In this case, the measurement doesn't tell you much.

check to see if the gas line coming into the house is big enough to support the water heater and the furnace at the same time. Call the gas co. and have them check their regulator for size and performance

manufacturing oils burning off of the heat exchanger. it will continue for about an hour of run time. if it continues longer than that, contact your installer.

the sch 40 venting is no longer code , it has to be upgraded to a more heat resistant pipe called 636 pipe , it is also a plastic pipe but can withstand alot more heat. the 636 pipe goes together with a acid glue/primer, you have to place primer on pipe then the glus and push peices together hold for a few secs and your good. hope this helps you

I was looking for a service manual, which you apparently do not supply. I was not looking for someone who will charge me a fee to get information. I can get that info directly from Bosch for free. Thank you for answering. John

balancing spool on the faucet ?

if its coil can get replacement by notifying bosch --u also can solder or braze the crack u can also try cold weld [j b weld ]

Sounds like you have a scaled up heat x get it checked out by a bosch service agent

1/ check overheat stat 2/ check fan esp the little flexie hose rear fan area for pinhole 3/check diaphrapm valve 4/ check micro switch best of luck

Open up the front cover - look at the printed curciut board and see if you have two or three capacitors that the tops are slightly raised...if so, those capacitors on the board need to be replaced...they should be competly flat.

HTH,

Mike...

Your vent pipe needs a cap. You should be able to find one at your local building supply store; just tell them your problem, and they will find the right product and let you know how to best install it.

The flame sensor is not sensing flame and the unit shuts off on safety. You can try cleaning the sensor, but will likely have to replace it. Also clean the burners. Sometimes there can be rust, dirt, or other dibri that causes an improper flame pattern and prevents the sensor from being fully in the flame.

With some units, the flame sensor is a seperate part, with others it is a part of the ignition assembly. Those can typically run 30 to 80 dollars for the part.

Replace the flame sensor