Question about Bosch AquaStar 125FXKIT-LP 125FX Liquid Propane Gas Tankless Water Heater w/ Hood

1 Answer

Electronic water heater burner often won't light tho pilot's on

Hi, I have a Bosch AQ 125XNG water heater with electronic ignition. The pilot always comes on, but the burner will not light 75% of the time, and often only when we first turn on the highest demand tap in the house, the washing machine set to hot, before we can open another tap and expect hot water out of it. But not even that works much of the time, and some of the upstairs taps will NEVER get hot water without this technique (even the dishwasher sometimes). Sometimes I can get it to light by blowing with all my might into the pilot flame and jumping back before my hair gets singed, but that usually doesn't work either. Or sometimes if you wait an hour it will work. It's a real **** shoot but usually you're saying "****" or "shoot"! I checked the battery voltage and they are over 1.4V so that doesn't seem to be the problem (instructions say only need replacement when below 1.2V). Replacing them doesn't always help anyway, or if it does, not for very long. But the ignition "clicking" when the water is turned on varies greatly in speed. When it is slow, I know the burner won't catch. When it is rapid there's a much better chance that it does.
It's only a few years old. What gives???

Posted by on

1 Answer

  • Level 2:

    An expert who has achieved level 2 by getting 100 points

    All-Star:

    An expert that got 10 achievements.

    MVP:

    An expert that got 5 achievements.

    Vice President:

    An expert whose answer got voted for 100 times.

  • Expert
  • 332 Answers

It sounds like you pilot lite is to far away from the burner, make sure that the burner is sitting in it;s purch, look thru the site glass it can be moved by hitting or bumping into the out side of the gas tubes on the outside of water heater, if not, the burner assembly may have soot on it. you might also want to make sure the filters are not clogged on the shut offs that will give it less pressure then it needs to make the unit come on,, write me , gary1121@aol.com

Posted on May 29, 2009

2 Suggested Answers

6ya6ya
  • 2 Answers

SOURCE: I have freestanding Series 8 dishwasher. Lately during the filling cycle water hammer is occurring. How can this be resolved

Hi,
a 6ya expert can help you resolve that issue over the phone in a minute or two.
best thing about this new service is that you are never placed on hold and get to talk to real repairmen in the US.
the service is completely free and covers almost anything you can think of (from cars to computers, handyman, and even drones).
click here to download the app (for users in the US for now) and get all the help you need.
goodluck!

Posted on Jan 02, 2017

co7196
  • 3433 Answers

SOURCE: Bosch AQ 125XNG water heater burner frequently won't light

May be That we have something we can try. first, what doesn't work most of the time? Blowing with all you mite or jumping out of the way before your hair gets singed?
I think it sounds like you might have a maladjusted ignitor. Mispositioned. Its not in the gas path. Sometimes this happens as the tungsten ignitor wears down. That can be adjusted by repositioning the ignitor so it is in the pat of the gas. Just don't test as you go. Set the ignitor so the arc is about 1/4 inch long and about 1/4 inch away from where the gass comes out. Keep clear of the access hole. The longer it takes to ignite, the more gas build up there is. Have your exhaust vent checked. restriction keeps it from drafting and drawing enought air to balance the air gas mixed to ignitable.

Be careful and be safe

Posted on May 18, 2009

Add Your Answer

Uploading: 0%

my-video-file.mp4

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

×

Loading...
Loading...

Related Questions:

3 Answers

Bosch 13Hwater heater problems


Question is how am I to know what model this is? And as stated the question answers itself.....Plumber removed...did he reinstall? of course but as stated the issue is unanswerable.
Does the Pilot light? or if this is an electronic unit than something in the feedback ignition sensor is amuck. Is this a 125VP, 125B, 125H. 38B or a 240FX, 250SX or 2400/2700 or newer?

Jun 16, 2014 | Bosch & Tankless LP Hot Water Heater

1 Answer

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.

Feb 01, 2013 | Bosch & Tankless LP Hot Water Heater

1 Answer

I have a Bosch AquaStar AQ-125-BNG tankless water heater. It has worked very well until recently. The problem: The hot water at the tap is turned off, the flame on the main burner keeps burning and...


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

Jul 05, 2010 | Bosch AquaStar Indoor Natural Gas Tankless...

2 Answers

New gas water heater pilot light will not ignite


Hi .. if this is a brand new heater, then you probably need to have the gas line bled. This means getting all the air out of the gas line feeding the burner. This can be done by constantly trying to light the burner or poilot . or it can be bled down by a HVAC tech.

Apr 09, 2010 | Rheem 40 GAL ELEC TALL Water Heater 6YR SC...

1 Answer

Hi Our gas water heater is not igniting


you need to replace the thermocouple its an electronic device that keep the gas flowing . the pilot light is always on and the thermo couple controls the flame. if it goes bad the flame goes out and the burner wont come on to heat the water, they are easy to replace and available at all home depot or a lowes kind of store.

Dec 01, 2009 | Water Heaters

1 Answer

Bosch AQ 125XNG water heater burner frequently won't light


May be That we have something we can try. first, what doesn't work most of the time? Blowing with all you mite or jumping out of the way before your hair gets singed?
I think it sounds like you might have a maladjusted ignitor. Mispositioned. Its not in the gas path. Sometimes this happens as the tungsten ignitor wears down. That can be adjusted by repositioning the ignitor so it is in the pat of the gas. Just don't test as you go. Set the ignitor so the arc is about 1/4 inch long and about 1/4 inch away from where the gass comes out. Keep clear of the access hole. The longer it takes to ignite, the more gas build up there is. Have your exhaust vent checked. restriction keeps it from drafting and drawing enought air to balance the air gas mixed to ignitable.

Be careful and be safe

May 15, 2009 | Bosch AquaStar 125FXKIT-LP 125FX Liquid...

1 Answer

No hot water, pilot light lights but no burner ignition


Thermo coupler may be defective. it controls the main gas valve by closing main if pilot is out. make sure thermo coupler bulb is positioned over and near tip of pilot flame, but not in the flame. Thermo couplers are inexpensive and easy to change out.

May 05, 2009 | Bosch & Tankless LP Hot Water Heater

1 Answer

Bosch tankless GWH 1600 H NG won't always ignite. The igniter sparks, but doesn't always light the gas. It just clicks. When installed it lit every time, now it takes more and more tries to get it to...


The manual says to hold a match near the pilot while the ignitor is trying. It says that if the unit lights the pilot orifice may be dirty or clogged. Then the manual says to check the voltage on the igniter. It should be 1.3 volts DC minimum if it is not means the electronic control box is defective.

Let me know the status ...Kevin

Mar 29, 2009 | Bosch 1600H-NG Natural Gas AquaStar...

Not finding what you are looking for?
Bosch AquaStar 125FXKIT-LP 125FX Liquid Propane Gas Tankless Water Heater w/ Hood Logo

963 people viewed this question

Ask a Question

Usually answered in minutes!

Top Bosch Water Heaters Experts

Colin Stickland
Colin Stickland

Level 3 Expert

22095 Answers

Donni Steen

Level 3 Expert

659 Answers

john h

Level 3 Expert

10998 Answers

Are you a Bosch Water Heater Expert? Answer questions, earn points and help others

Answer questions

Manuals & User Guides

Loading...