Plumbing

Plumbing Questions? Ask a Plumber and Get Answers ASAP.

Ask an Expert,
Get an Answer ASAP!

Plumbing

I have a Bosch tankless water heater. Model AQ 250 SX NG. It

Customer Question
I have a Bosch tankless...
I have a Bosch tankless water heater. Model AQ 250 SX NG. It is giving me an A2 Error Message. It fires up for 10 seconds and the quits. Any ideas?
Submitted: 2 years ago.Category: Plumbing
Show More
Show Less
Ask Your Own Plumbing Question
Answered in 7 minutes by:
12/2/2015
Plumber: Phil, Mechanical Engineer. replied 2 years ago
Phil
Phil, Mechanical Engineer.
Category: Plumbing
Satisfied Customers: 9,168
Experience: Retired mech. contractor, shop owner, 51 yrs experience.
Verified

Hello, its probably a flame sensing issue, resolved by cleaning the flame sensor rod off with a scotchbrite pot scrubber pad.

Look inside the cover of the unit for the wiring diagram it should have the code read out inside. If you want coaching on the trouble shooting

Please attach a well focused, close up photo of the wiring diagram glued inside the service panel, the picture needs to betaken from straight on, in very good light.

You can use the paper clip- icon at the right end of the tool bar at the top of this dialog box to attach it here. ,Include a picture of the thermostat wire connections to the printed circuit board in the same area.

If you have an error code showing, tell me what the code read out is on the wiring diagram or a sticker next to the diagram please.

If there is no paper clip-icon, look for the '+attach files' link at left of your send button.

I can mark it up with trouble shooting instructions.

You will need a multi meter ($30 at a hardware store) and some experience working with appliances, let me know a lot about your skill sets in those regards.

If I miss you tonight, I will pick up your response first thing in the morning.

Ask Your Own Plumbing Question
Customer reply replied 2 years ago
attached is the diagram of the unit. What next? I have a multi meter. Thanks for your help.
Customer reply replied 2 years ago
A2 is the error message.
Plumber: Phil, Mechanical Engineer. replied 2 years ago

Thanks for the diagram

http://screencast.com/t/aaXjsmoI

Let me know how those tests go, if the switch tests open, you can buy the part from your local dealer, if you have trouble with that let me know, we can go from there without a time limit.

If the switch tests closed and you do not find a bad wire connection, there is a problem with the printed circuit board.

We can do a heat stress test on it.

Use a hair drier to slowly warm the printed circuit card up to120F or a bit warmer, but not over 140F... if there is any change in the error codes or other water heater error code or behavior... the card has a cracked micro circuit that opens and closes as the card expands and contracts... that proves a bad printed circuit card.

No change however does not prove the card is good however... but a change proves the card is definitely bad.

Thanks for letting me work with you. When we are finished,if my answer has been polite, professional, and thorough, please locate the 'rate your expert button' and click one of the ratings .If you still need help let me know!. Expert is not paid for assisting you until you rate answer. Feel free to follow up for30 days at no additional cost.

Ask Your Own Plumbing Question
Customer reply replied 2 years ago
I will try this in the morning. Thanks for your help. Toby
Plumber: Phil, Mechanical Engineer. replied 2 years ago

Hello again Toby. You can also use an electronic thermometer and focus it on the tube that the over heat switch is attached to and notice when it opens and shuts the burner off... if it shuts off below 160 to 180F then its bad, if it shuts off over 180F then there is a insufficient water flow due to water scale build up in the heat exchanger or inlet water filter.

Let me know what you can discover, we can go from there.

Ask Your Own Plumbing Question
Customer reply replied 2 years ago
I have a laser temp gun. Would that work?
Plumber: Phil, Mechanical Engineer. replied 2 years ago

Hello again, the lazer gun might work, it depends on the surface and angle the laser beam strikes the tube, you could try it and see if it seems close enough.. hopefully the switch will be so far out of range that it trips just as the tube begins to get warm... then we know for sure that its bad.

Ask Your Own Plumbing Question
Ask Phil Your Own Question
Phil
Phil
Phil, Mechanical Engineer.
Category: Plumbing
Satisfied Customers: 9,168
9,168 Satisfied Customers
Experience: Retired mech. contractor, shop owner, 51 yrs experience.

Phil is online now

A new question is answered every 9 seconds

How JustAnswer works:

  • Ask an ExpertExperts are full of valuable knowledge and are ready to help with any question. Credentials confirmed by a Fortune 500 verification firm.
  • Get a Professional AnswerVia email, text message, or notification as you wait on our site. Ask follow up questions if you need to.
  • 100% Satisfaction GuaranteeRate the answer you receive.

JustAnswer in the News:

Ask-a-doc Web sites: If you've got a quick question, you can try to get an answer from sites that say they have various specialists on hand to give quick answers... Justanswer.com.
JustAnswer.com...has seen a spike since October in legal questions from readers about layoffs, unemployment and severance.
Web sites like justanswer.com/legal
...leave nothing to chance.
Traffic on JustAnswer rose 14 percent...and had nearly 400,000 page views in 30 days...inquiries related to stress, high blood pressure, drinking and heart pain jumped 33 percent.
Tory Johnson, GMA Workplace Contributor, discusses work-from-home jobs, such as JustAnswer in which verified Experts answer people’s questions.
I will tell you that...the things you have to go through to be an Expert are quite rigorous.

What Customers are Saying:

You did one super job of explaining to me everything there is to know about this fridge. I'm looking forward to asking you questions in the future.

JimmyBagley, IA

Wonderful service, prompt, efficient, and accurate. Couldn't have asked for more. I cannot thank you enough for your help.

Mary C.Freshfield, Liverpool, UK

This expert is wonderful. They truly know what they are talking about, and they actually care about you. They really helped put my nerves at ease. Thank you so much!!!!

AlexLos Angeles, CA

Thank you for all your help. It is nice to know that this service is here for people like myself, who need answers fast and are not sure who to consult.

GPHesperia, CA

I couldn't be more satisfied! This is the site I will always come to when I need a second opinion.

JustinKernersville, NC

Just let me say that this encounter has been entirely professional and most helpful. I liked that I could ask additional questions and get answered in a very short turn around.

EstherWoodstock, NY

Thank you so much for taking your time and knowledge to support my concerns. Not only did you answer my questions, you even took it a step further with replying with more pertinent information I needed to know.

RobinElkton, Maryland

< Previous | Next >

Meet the Experts:

Marc

Marc

Plumber

1,127 satisfied customers

Plumbing heating & home maintenance contractor

Jerry

Jerry

Plumber

784 satisfied customers

over 20 years residential plumbing experience.

Theplumber717

Theplumber717

Plumber, Hvac Tech

656 satisfied customers

Lic Plumbing contractor, 28/yrs res,com,repair,Universal HVAC Tech

Phil

Phil

Mechanical Engineer.

9,168 satisfied customers

Retired mech. contractor, shop owner, 51 yrs experience.

Mario

Mario

Master Plumber

604 satisfied customers

Master Plumber, Fire Sprinkler, and Jobbing Spec.

Bud

Bud

Plumber

538 satisfied customers

22 Years Field Experience - 17 Years Business Ownership - Residential or Light Commercial

Rick Mather

Rick Mather

Building Inspector

498 satisfied customers

Assistant Building Official, HVAC Tech

< Previous | Next >

Related Plumbing Questions
My tankless water heaters ran out of propane, then when I
my tankless water heaters ran out of propane, then when I got a delivery I cannot get it to reset and work … read more
Brian Weeks
Brian Weeks
69 satisfied customers
I am trying to replace hose for k-10433-bn spray hose. How
I am trying to replace hose for k-10433-bn spray hose. How do i get old part out? … read more
WCohn
WCohn
Journeyman Plumber
Journeyman License
1,351 satisfied customers
I have 2 rianni systems that are not producing hot water.
I have 2 rianni systems that are not producing hot water. … read more
WCohn
WCohn
Journeyman Plumber
Journeyman License
1,351 satisfied customers
We just got a one piece Kohler toilet installed, didn't
Hi, we just got a one piece Kohler toilet installed, didn't tighten down too much … read more
Brian Weeks
Brian Weeks
69 satisfied customers
Have a ge water softener water is building up in the unit. 3
have a ge water softener water is building up in the unit … read more
Rick the plumber
Rick the plumber
Owner
9,857 satisfied customers
I replaced the stems in my Roman tub handles and now the
Hi, I replaced the stems in my Roman tub handles and now the water won't turn off. … read more
Brian Weeks
Brian Weeks
69 satisfied customers
We have been away 4 days and came back to find our Rinnai
We have been away 4 days and came back to find our Rinnai tankless hot water heater alarm going off. The water temp is down to 65. Our tankless hot water heater is located on the outside of our house.… read more
WCohn
WCohn
Journeyman Plumber
Journeyman License
1,351 satisfied customers
Is it possible to convert a Kohler touchless toilet to a
Is it possible to convert a Kohler touchless toilet to a manual flush … read more
WCohn
WCohn
Journeyman Plumber
Journeyman License
1,351 satisfied customers
Our tankless water heater works half the time, does not work
Our tankless water heater works half the time, does not work half the time. Perhaps an hour after there is no hot water, we turn it on and there is hot waer. What can we do? This is a Country Inn and … read more
canuck the pro
canuck the pro
251 satisfied customers
Iam on the top floor of an apartment builfing. my toilt is
Iam on the top floor of an apartment builfing. my toilt is not flushing fully and is overfilling with water. not overflowing but I hav bailed out. there is only water in it and a small piece of paper.… read more
WCohn
WCohn
Journeyman Plumber
Journeyman License
1,351 satisfied customers
Where do I make the electrical connection for my RL94e? I
Where do I make the electrical connection for my RL94e? I opened the front panel, but cannot find a place to connect power cord. … read more
WCohn
WCohn
Journeyman Plumber
Journeyman License
1,351 satisfied customers
I have a problem with flushometer. I can flush but I have to
I have a problem with flushometer. I can flush but I have to hold down flush handle to insure it finishes the flush. How can I fix?… read more
canuck the pro
canuck the pro
251 satisfied customers
Looking for plumber who knows moen kitchen faucet...leaking
looking for plumber who knows moen kitchen faucet...leaking under sink and dripping from top faucet … read more
Phil
Phil
Mechanical Engineer.
9,168 satisfied customers
I have a tankless Rinnai hot water heater and my water to my
I have a tankless Rinnai hot water heater and my water to my house is shut off. Will this be a problem? … read more
WCohn
WCohn
Journeyman Plumber
Journeyman License
1,351 satisfied customers
I would like to see if I can add a half bath in my house. We
Hey Rick, I would like to see if I can add a half bath in my house. We have a ranch with a basement, however the place where we want to add the half bath is on the main floor in a room that is behind … read more
Rick the plumber
Rick the plumber
Owner
9,857 satisfied customers
The bidet sounds as if it is working (no battery problem)
The bidet sounds as if it is working (no battery problem) and the "washing piece" moves back and forth, BUT there is no water coming out. Check the plug into the electrical unit and it is ok. Where el… read more
WCohn
WCohn
Journeyman Plumber
Journeyman License
1,351 satisfied customers
Need to know the part number for replace washer. The kit I
Need to know the part number for replace washer. The kit I bought part number is ***** The Kholer was installed in 1993. Can't find the paperwork or instructions for the unit. … read more
canuck the pro
canuck the pro
251 satisfied customers
There is a faucet handle coming out of our basement floor
There is a faucet handle coming out of our basement floor next to the sewer pipe. The sewer pipe is closed off. Would like to know what this faucet is … read more
Rick the plumber
Rick the plumber
Owner
9,857 satisfied customers
Disclaimer: Information in questions, answers, and other posts on this site ("Posts") comes from individual users, not JustAnswer; JustAnswer is not responsible for Posts. Posts are for general information, are not intended to substitute for informed professional advice (medical, legal, veterinary, financial, etc.), or to establish a professional-client relationship. The site and services are provided "as is" with no warranty or representations by JustAnswer regarding the qualifications of Experts. To see what credentials have been verified by a third-party service, please click on the "Verified" symbol in some Experts' profiles. JustAnswer is not intended or designed for EMERGENCY questions which should be directed immediately by telephone or in-person to qualified professionals.

Disclaimer: Information in questions, answers, and other posts on this site ("Posts") comes from individual users, not JustAnswer; JustAnswer is not responsible for Posts. Posts are for general information, are not intended to substitute for informed professional advice (medical, legal, veterinary, financial, etc.), or to establish a professional-client relationship. The site and services are provided "as is" with no warranty or representations by JustAnswer regarding the qualifications of Experts. To see what credentials have been verified by a third-party service, please click on the "Verified" symbol in some Experts' profiles. JustAnswer is not intended or designed for EMERGENCY questions which should be directed immediately by telephone or in-person to qualified professionals.

Show MoreShow Less

Ask Your Question

x