20 Most Recent Bosch AquaStar Indoor Natural Gas Tankless Water Heater with Vent Hood #125 - Page 3 Questions & Answers

sounds like the part he cleaned should get replaced, have him come back and replace the part instead of cleaning it, we some times clean it hoping to save time and money, but if that doesn't fix it it should be replaced.

1) I would contact BOSCH, or a service technician:
Tankless are affected by many internal and external factors and can be a combination of factors:
http://www.boschhotwater.com/HelpfulResources/TechnicalSupport/BoschAquaStarModels/2400ESTechSupport/Troubleshooting/tabid/1295/Default.aspx

2) Google search 'bosch tankless water heater fixya' to see cross section of problems/solutions: .
For example:
http://www.fixya.com/support/p949576-bosch_1600h_lp_liquid_propane_aquastar_a/solutions

3) Read manual for yearly maintenance protocol.
For example, tankless should be de-limed each year.
a) U-tube search for 'de-lime tankless water heater'
b) Open following link with photos of de-liming in downloadable pdf format
http://waterheatertimer.org/pdf/Delime-tankless-water-heater.pdf

5) All costs are energy.
You can also add simple tank-type water heater that can be turned on when tankless is offline.
http://waterheatertimer.org/How-to-install-gas-water-heater.html

Before calling service technician, open following links for Bosch troubleshooting resources:
http://waterheatertimer.org/Troubleshoot-Bosch-Tankless-water-heater.html
Resources at Bosch
http://www.boschhotwater.com/HelpfulResources/TechnicalSupport/BoschAquaStarModels/tabid/370/Default.aspx
Typical Bosch Aquastar manual:
http://waterheatertimer.org/pdf/Bosch-aquastar-170vp-manual.pdf

All tankless and tank-type gas water heaters require regular cleaning and maintenance.
It is unknown if your unit needs maintenance or repair parts, but catching up on maintenance using information from manual is good place to start.
Gas appliances are increasingly complicated and experienced technician is good resource to have in local area before installing tankless.

Tankless should never be installed with plastic pipe, PVC or CPVC etc.

Before calling service technician, open following link for Bosch tankless troubleshooting resources, including Bosch contact information, typical manuals, error codes, tech support, parts, fuel-saver calculator, service bulletins, water heater forum, fixya links, disclaimers, and links for finding service technician.
http://waterheatertimer.org/Troubleshoot-Bosch-Tankless-water-heater.html

Read manual cover to cover, make sure tankless receives yearly maintenance as outline in manual.

Add a comment with your experience so others with same-similar problem can benefit.

Also take advantage of fixya expert assistance live.
For a price, expert works with you while you work on water heater or any do-it-yourself project.
Fixya is always less expensive than a service call.

is it power vented or is it draft vented if it is draft vented that is not uncommon sometime u get tiny back drafts and u smell a little burnt gas if u are really concerned get a carbon monoxide detector and place it within 4 feet of the unit @around 4 feet off the ground

the fact that you had steam coming out of the pipes would indicate that the temperature sensor has failed. and may have caused damage to other components internally as well

Check and be sure gas knob is in the pilot lighting position and pushed in. Try to manually light with a match. Make sure gas **** is in the on position. Posible air in the gas line. Bled off air. gas valve or regulator has failed..

Insufficient gas presure. Check gas presure exiting regulator exrternal of water heater. If presure is at 3.7-inches water column gas valve is defective.

I had a similar problem with mine and it turned out to be a plugged air vent sceen. This is the small dome like sceen on the gas valve. I vaccumed out the unit and have not had the pilot go out in over a year.

the unit should still be under warranty sounds like a sticking solenoid problem

The problem with all that type of water heater is that once the hot tap is turned on sufficient flow must be maintained through the water heater to keep the main gas burner alight. If the heat adjuster is turned up to high, then the person using the hot water will turn it down to a low rate which means the main burner will turn off and result in cold water. Try setting the heat control to the lowest setting that still gives hot enough water. If you have a thermometer adjust control for a temperature of around 50 to 55 degrees Celcius. You may have to fiddle with fine adjustments to get the temperature and flow rates to maintain a constant output of hot water. You may still have intermittent problems. If the heater only supplies baths or showers you could set the temperatuer even lower (45 to 50) to ensure that the hot tap is used more than the cold which will maintain flow and therefore heat.

It sounds to me like you tried about everything I would. So I think you're already thinking about what I would do next. Try the flame sensor,and as last resort check all connection . Remove wires one by one clean and reattach. If all else fails change cotrol board. It's very hard to fix when it's not consistent. Good luck. Thanks

Flow sensor switch is bad

The pilot light can be blown out just by the main gas being ignited especially if the pilot flame is a little weak. Some times a bit of grit gets into the pilot nozzle reducing the flow and hence a weak flame. Try cleaning the piolt jet nozzle with a fine piece of wire. You may have to dismantle the jet nozzle to clean it properly.

Possibly the flow switch is in need of replacing

the thermocouple lead needs to be replaced this is the copper tubing that runs from the pilot to the control it is about 5mm in diameter and costs about $80 at any pumbing supplies

there is a small dia copper pipe which has a thermal coupling on it the end of it sits in the flame of the pilot light,
if it fails which it does after about 25-15 months,it shuts down the gas burner

These units need lots of flow to start and run. Set the temp on the unit lower and the people in the shower will have to use more hot and less cold which will make the unit more stable.

EC is no ionisation and is usually the result of a gas pipe or gas supply pressure problem. The other problem is the installer never adjusted the CO2 levels. If the yellow paint on the two screws inside the cabinet is still intact, the plumber did not do his job. Make sure this is done with calibrated CO2 analyzer that was calibrated within the last 6 months.