20 Most Recent Bosch 2400ES LP AquaStar 6.4 GPM Indoor Tankless Liquid Propane Water Heate Questions & Answers


Bosch AquaStar 2400ES-LP Problem with Vibration

Vibrations were caused by the worn water pump bearings. They could be reduced by reducing the speed of the pump. Vibrations in the water system that is connected to your neighbor may be caused by a change in pressure in the system, if the water pipes are not isolated, and they touch the wall at some oscillation frequency.
11/5/2017 3:14:15 PM • Bosch 2400ES LP... • Answered on Nov 05, 2017

I have been getting both

You would need to check that you have the correct burner pressure that would be part of the conversion. Its NOT all ways pre-set as some think to the correct pressure .
5/29/2017 2:00:19 PM • Bosch 2400ES LP... • Answered on May 29, 2017

Rinnai infinity hot water service, goes hot and cold...not fun in the shower!

We had the same problem - the hot water would only be hot for 3 -5 minutes and shut off, then we had to turn the water off, wait a few minutes, and do it again. VERY FRUSTRATING.

Solution: The Rinnai serviceman showed me the heat-exchanger blower/fan: It was clogged with dust and moths.

Another clue: Our Rinnai was extremely noisy when the heat came on. After the fan was cleaned and replaced, it is nearly silent.

If you are reasonably machanically inclined:

The blower-fan is located in the lower central area of the unit (at least on our unit). If you draw imaginary north-south, east-west lines through the center of the unit, the fan is in the lower-left quadrant. There is a spring clamp securing the black rubber accordian-like tube to the fan. There are two screws that secure the fan to the unit. there are two plugs that connect to the fan, as well as a third air-flow sensor that should be removed. then you can look at the fan unit, as well as the grill on the underside of the heat-exchanger that should be cleaned.

My thought was to go out and get a simple bug-screen, and place it over the air-input outlet vent going outside, but the repair guy said that although it may sound good, if that screen ever gets clogged, or reduces airflow to the Rinnai, then the unit will work harder, or even shut off, giving the same problem,
4/5/2013 3:43:20 AM • Bosch 2400ES LP... • Answered on Apr 05, 2013

Aqua star runs on and was running water to out

Problem is not clear

Before calling service technician, open following link for Bosch troubleshooting resources including contact information for Bosch:
6/9/2011 7:51:35 AM • Bosch 2400ES LP... • Answered on Jun 09, 2011

Will not stay lit.

You posted under Bosch tankless water heater.
Fixya is ready to assist resourceful do-it-yourselfer, so read information below, and if you are unable to determine what problem is, post another question saying what you've done so far, or contact service technician and when technician arrives, ask that person tricks and tips for maintaining your tankless water heater.

1) Best place to start is troubleshoot section of manual.
Bosch manuals:

2) Open pdf of typical manual: troubleshoot section page 33.

3) BOSCH error codes

4) Bosch has online tech support form:

5) Bosch problems at Fixya:

6) Read manual cover to cover
and make sure maintenance is scheduled.
For example de-liming is recommended each year.
Utube search de-lime tankless water heater

7) Install DIY tank-type gas water heater and avoid the whole headache

Add a comment for more free help.
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.
3/11/2011 11:44:43 AM • Bosch 2400ES LP... • Answered on Mar 11, 2011

My rinnai heater keeps my

if it has been constant from instalation it might be that ur shower head is rated too low to get enogh gpm ( gallons per minute) it will tell u most of the time around the shower head where it threads onto the spot of the wall what the gpm is. alot of the energy saver heads are restricting tehgpm to 1.5 or .5 gpms to conserve water well the water heater will only operate correctally around .5 gpm depending on model so if u are not pulling enough water u will not turn the water heater on to get ur hot water all the time so go to lowes ( or locally trusted hardware) and get a new shower head make shure u look for the gpm on teh head and check in ur owners manual to see what gpm ur water heater kicks on

P.S. if ur shower head is rated at higher gpm say 1.5 and it is corroded or pluged up say with lime it is going to restrict it causing a lower gpm
1/14/2011 11:51:35 PM • Bosch 2400ES LP... • Answered on Jan 14, 2011


There are a few things that could make it go hot and cold...
First we know that the flame will light or there would be no hot water...
So... either the flame is not being sensed... the flame sensor is bad....
or... the flow switch is acting up and the flow switch is not sensing water flow properly and is shutting the flame down....
I would find the flame sensor first and clean or replace that...
Then I would check the power across the flow switch while water is running...this will tell if the switch is cutting in and out...

If all else fails then the main control could be bad... be that would be the last resort...

12/19/2010 7:52:45 PM • Bosch 2400ES LP... • Answered on Dec 19, 2010

Bosch tankless water heater lp gas pilot won't

Hi. I recommend that you move the thermocouple further into the flame and see if that solves your problem. If it does, fine. If not, replace the thermocouple. J.
7/5/2010 3:08:03 AM • Bosch 2400ES LP... • Answered on Jul 05, 2010

Why am i getting a A3 error code on my bosch aqua

Question is though, why would this fail after only six months?
6/29/2010 6:42:46 PM • Bosch 2400ES LP... • Answered on Jun 29, 2010

Water tempeture gets hot then cool

Have you tried turning off the valves to the water heater and making sure you have no water flow out of the hot water tap? When this happens, often it is because of a problem with a shower cartridge allowing the cold water to cross over into the hot water side. It makes the unit think that the flow has reduced and the heater will turn down or shut off. Then things bounce back and forth Hot to Cold then back to Hot.
4/5/2010 12:35:05 PM • Bosch 2400ES LP... • Answered on Apr 05, 2010

Hot water pipe leading to rainni water heater not

Use a hair dryer to warm it.
1/6/2010 4:57:36 PM • Bosch 2400ES LP... • Answered on Jan 06, 2010

Venting of Bosch 2400es in the basement

Yep they make gas pipe for that .Lowes should have it.
3/15/2009 3:48:54 PM • Bosch 2400ES LP... • Answered on Mar 15, 2009

Rinnai r70e warm not hot

This's been a cold year!
Is this an instantaneous water heater?
If it's outside or on an un-insulated wall in an unheated area this could very well be all that's wrong with it!
Is your heater well insulated?
Are your pipes well insulated?
Is it in a heated area?
If not I would insulated it real good and try moving it to an area that's heated!
Has this been helpful?
1/21/2009 8:48:46 PM • Bosch 2400ES LP... • Answered on Jan 21, 2009

Running water in 2 sinks just to get hot water from a bosch

you can put in a circulatating pump that is controller with a timer and a thermostat so the when yo need heat water the most its readilly available and when you don't it's off, the only thinsg thing that you would have to do it tye in the supply and the return and then insulate the pipes.
12/26/2008 2:07:47 AM • Bosch 2400ES LP... • Answered on Dec 26, 2008

Why is the Bosch high flow 21e system while showering going cool & then returns to the set temperature?

If your Bosch Highflow 21e hot water system is experiencing fluctuations in water temperature while showering, it could be caused by a few different factors. Here are some possible reasons for this issue:
  1. Flow rate too high: The hot water system may not be able to keep up with the demand if the showerhead or tap is allowing too much water to flow through. This can cause the water temperature to drop suddenly. Try reducing the flow rate by turning down the tap or using a low-flow showerhead.
  2. Water pressure fluctuations: If the water pressure in your home fluctuates, it can cause the hot water temperature to vary. This can be caused by various factors, such as other appliances using water at the same time, or changes in municipal water supply pressure. Installing a pressure regulator or a flow restrictor may help to stabilize water pressure.
  3. Blocked or dirty water filter: A clogged or dirty water filter in the hot water system can restrict water flow, causing the water temperature to fluctuate. Check the filter and clean or replace it if necessary.
  4. Malfunctioning thermostatic mixing valve: The thermostatic mixing valve (TMV) regulates the water temperature in the hot water system. If it's faulty or dirty, it can cause temperature fluctuations. A licensed plumber or technician can inspect the valve and replace it if necessary.
  5. Faulty temperature sensor or control board: If the temperature sensor or control board in the hot water system is faulty, it may not be able to maintain a consistent water temperature. A technician can diagnose the issue and repair or replace the faulty component.
If you're unsure about how to diagnose or fix the issue with your hot water system, it's best to contact a licensed plumber or technician for assistance.
3/9/2023 3:47:20 PM • Bosch Water... • Answered on Mar 09, 2023

My old tankless naturMy gas water heater Bosch model JSRZ 5-T PG, it is not starting automatic it has magnetic sensor valve in water inlet

The Bosch JSRZ 5-T PG tankless gas water heater may not start automatically because of problems with the magnetic sensor valve, power supply, or control unit/thermostat. Possible troubleshooting steps are:
  • inspect the water inlet valve and replace if faulty
  • confirm that power to the unit is functioning
  • if the problem continues, seek professional repair service.
1/29/2023 11:17:51 AM • Bosch Water... • Answered on Jan 29, 2023

No water coming out of hot water taps with a Bosch Water Wizard 10P?

Do you live in a climate where the hot water line could have frozen? If your heater did freeze up, that could be very bad. This is because water actually expands when it freezes and can do a lot of damage to pipes and to the water heater itself. My other thought is possibly a clogged in line water filter. But typically a clogged water filter would make it run with reduced pressure rather than a complete shutdown all water flow.
1/20/2023 6:10:26 AM • Bosch Water... • Answered on Jan 20, 2023

Can you help with these Bosch 715 EFS GWH Error Codes? AF, 40, 07 -

1/10/2023 7:22:20 PM • Bosch Water... • Answered on Jan 10, 2023
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