Terminator Aquastar 125FX Tankless Water Heater: FX Hood Horizontal Vent Logo
STEVE ENABNIT Posted on Apr 27, 2007
Answered by a Fixya Expert

Trustworthy Expert Solutions

At Fixya.com, our trusted experts are meticulously vetted and possess extensive experience in their respective fields. Backed by a community of knowledgeable professionals, our platform ensures that the solutions provided are thoroughly researched and validated.

View Our Top Experts

BOSCH AQ125FX TANKLESS WATER HEATER

The water heater won't ignite promptly. It takes turning on the water 5 to 10 times before it will ignite. It is 5 years old. It has worked great until last 6 months.

  • 2 more comments 
  • debbie05 Feb 12, 2008

    having problem with the tank not igniting. have to push reset button at least once per day, this unit is an outdoor model

  • Anonymous Apr 19, 2008

    continue to get er code - what to do please

  • Anonymous Nov 12, 2008

    I have the same problem. The pilot does not go on all the time. Sometimes I have to turn the hot water on and off a few times at the faucet. I tried rebuilding the water valve. No luck. I tried replacing the piezo. No luck. I tried replacing the thermocouple. No luck. I tried replacing the pilot tube (assuming it had a clog). No luck. The only thing that seems to work right now is to unscrew the pilot from the burner assembly and just let it hang there an inch away from the burner. This seems to resolve the problem, but is, as you can imagine, not very safe. Short of replacing the electronics, I am at a loss of what would cause it.

    Having the pilot assembly sit 1" outside of the burner works, so I assume it has something to do with lack of oxygen or even a loose wire of some sort.


  • Anonymous Mar 11, 2009

    Same for me. The vent fan starts when the hot water tap is turned on. The pilot does not light nor the burner start. Unfortunately, this is our only source for hot water so I need to get it fixed. Good luck with yours.



    1. Fan starts

    2. igniter does not spark

    3. Pilot doesn't light

    4. Wife yells

×

5 Answers

Anonymous

Level 1:

An expert who has achieved level 1.

Mayor:

An expert whose answer got voted for 2 times.

  • Contributor 1 Answer
  • Posted on Mar 12, 2009
Anonymous
Contributor
Level 1:

An expert who has achieved level 1.

Mayor:

An expert whose answer got voted for 2 times.

Joined: Mar 11, 2009
Answers
1
Questions
0
Helped
2404
Points
3

Well, after an hour of internet searching, I can give some real advice.

http://www.houseneeds.com/shop/HeatingProducts/WaterHeating/parts/bosch125fxbrasspartsbuy.asp

This website has excellent trouble shooting and illustrated parts breakdowns. They'll even place your parts order too.

For my AQ125FX the problem was the Electronics Control Box (PN 87007207011). I didn't have the 1.3 Volts DC required for the igniter. I also recommend that you check the Water Inlet Filter (PN 8700507059) for deposits and blockage. While there is no specified time change for the filter, I suggest that it be changed at least every 2 years (cheap insurance at $10 a filter). There is a Service / Replacement kit for the Water Inlet Valve (PN 8703406178) if you've got a gummed up valve but it should not be necessary if the following things happen when you turn on the hot water tap:

1. The Exhaust Fan Vent Motor starts
2. The Pressure Demand Micro Switch closes (this is the black device at the very bottom of the unit)

The key to this system is downstream water pressure (demand for hot water) and the Water Inlet Valve and Pressure Demand Micro switch is the heart with the Electronics Control Box being the brains. I hope this helps you with your Bosch Aquastar water heater.

Anonymous

Level 2:

An expert who has achieved level 2 by getting 100 points

MVP:

An expert that got 5 achievements.

Novelist:

An expert who has written 50 answers of more than 400 characters.

Governor:

An expert whose answer got voted for 20 times.

  • Expert 116 Answers
  • Posted on Apr 27, 2007
Anonymous
Expert
Level 2:

An expert who has achieved level 2 by getting 100 points

MVP:

An expert that got 5 achievements.

Novelist:

An expert who has written 50 answers of more than 400 characters.

Governor:

An expert whose answer got voted for 20 times.

Joined: Mar 10, 2007
Answers
116
Questions
0
Helped
76019
Points
315

These heaters work when a pressure drop is sensed in the water supply line. The pressure sensor is likely blocked with sediment from the city supply. You may want to call for service.

Ad
A

Anonymous

I am unable to locate the reset buttom . I have the AQ125FX if you could tell me where to locate it i would greatly appreiciate your expertise

A

Anonymous

I noticed mine does not ignite properly during the summer. I believe the incoming water temperature may be a factor.

Anonymous

Level 1:

An expert who has achieved level 1.

  • Contributor 1 Answer
  • Posted on Mar 23, 2009
Anonymous
Contributor
Level 1:

An expert who has achieved level 1.

Joined: Nov 12, 2008
Answers
1
Questions
0
Helped
2404
Points
1

I finally got a heating and plumbing guy to look at my water heater. Turns out the problem was with gas pressure. The pressure was very low coming into the house at at the appliance. He turned up the pressure on the regulator coming into the house and the water heater has been working just fine.

Add Your Answer

×

Uploading: 0%

my-video-file.mp4

Complete. Click "Add" to insert your video. Add

×

Loading...
Loading...

Related Questions:

0helpful
1answer

My red light is flashing

Gas water heater?
Copy following link to troubleshoot be gas control valve:
http://waterheatertimer.org/How-to-troubleshoot-gas-water-heater.html#intellivent

Add comment and describe type and brand of water heater

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

0helpful
1answer

Bosch Confort S 13 BP tankless water heater won't ignite, It clicks but no gas going thru valve

The S 13 BP is a simple unit that does not have a pilot light. It uses electronic ignition on demand, which is what you hear clicking. If there is no gas going through and you've verified there is gas to the inlet, then it has to be the gas control valve.
1helpful
1answer

I have a Bosch GWH 425 HNO propane Tankless Water Heater which began intermittently exploding when demand for hot water occurs.

Call a qualified service tech immediately.
Gas explosion indicates dirty combustion parts, and gas is not fully igniting when tankless turns on the gas. So gas builds up and then explodes causing serious damage to tankless, and serious risk to homeowner.

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

0helpful
1answer

Our tankless water heat will not heat the water-it won't ignite

Question posted under Boasch tankless. Model number not known.
Before calling service technician, open following link for Bosch troubleshooting resources, including phone and contact for Bosch, error codes, and possible manual, plus hours of reading and research:
http://waterheatertimer.org/Troubleshoot-Bosch-Tankless-water-heater.html

As you know from reading manual, tankless water heaters require yearly maintenance by trained service technician, or by homeowner. This action would check gas and pressure, venting draft, condensation drain, burner and combustion parts, igniter and-or pilot light, electrical connections, air intake and general condition of plumbing.
Problem you describe does not include error code.
Open following link for possible help with general plumbing problem:
http://waterheatertimer.org/pdf/No-Error-Code.pdf

Add a comment with model number that appears on side of unit, and I can directly locate possible service bulletins and further troubleshoot resources available at Bosch for possible do-it-yourself diagnosis and repair.
0helpful
1answer

We have a bosch tankless water heater in a 1600 sq ft home...it works great except in one faucet (the spare bathroom sink)...sometimes the hot water comes out, sometimes it doesnt, sometimes it takes...

Since you have hot water at all the other fixtures, the problem lies in the sink, not the water heater. It could be that the sink is farther away from the water heater than the other fixtures. It would take longer to get hot water.
0helpful
1answer

Bosch 1600H-NG Natural Gas AquaStar AquaStar Natural Gas Tankless Water Heater. Problems with constant hot water. The heater turns ok but (i think) when i turn on the cold side the heater stops. at...

Possible flow sensor issue. Check to see if your water pressure fluctuates a lot or is fairly steady. These units are sensitive to the pressure. take care.
0helpful
1answer
0helpful
2answers

Power cuts & tankless water heaters

A tankless water heater, by definition, has no storage capacity. It doesn't heat the water until you turn on the tap. When the power is off, you will have no hot water.
Not finding what you are looking for?

2,414 views

Ask a Question

Usually answered in minutes!

Top Terminator Kitchen Ranges Experts

Paul Carew

Level 3 Expert

3808 Answers

john h

Level 3 Expert

29494 Answers

ADMIN Andrew
ADMIN Andrew

Level 3 Expert

66980 Answers

Are you a Terminator Kitchen Range Expert? Answer questions, earn points and help others

Answer questions

Manuals & User Guides

Loading...